Recent studies have suggested that abnormal acidification of lysosomes induces autophagic accumulation of amyloid-βin neurons,which is a key step in senile plaque formation.Therefore,resto ring normal lysosomal funct...Recent studies have suggested that abnormal acidification of lysosomes induces autophagic accumulation of amyloid-βin neurons,which is a key step in senile plaque formation.Therefore,resto ring normal lysosomal function and rebalancing lysosomal acidification in neurons in the brain may be a new treatment strategy for Alzheimer's disease.Microtubule acetylation/deacetylation plays a central role in lysosomal acidification.Here,we show that inhibiting the classic microtubule deacetylase histone deacetylase 6 with an histone deacetylase 6 shRNA or thehistone deacetylase 6 inhibitor valproic acid promoted lysosomal reacidification by modulating V-ATPase assembly in Alzheimer's disease.Fu rthermore,we found that treatment with valproic acid markedly enhanced autophagy.promoted clearance of amyloid-βaggregates,and ameliorated cognitive deficits in a mouse model of Alzheimer's disease.Our findings demonstrate a previously unknown neuroprotective mechanism in Alzheimer's disease,in which histone deacetylase 6 inhibition by valproic acid increases V-ATPase assembly and lysosomal acidification.展开更多
Global coral reef ecosystems have been severely degraded due to the combined effects of climate change and human activities.Changes in the seawater carbonate system of coral reef ecosystems can reflect their status an...Global coral reef ecosystems have been severely degraded due to the combined effects of climate change and human activities.Changes in the seawater carbonate system of coral reef ecosystems can reflect their status and their responses to the impacts of climate change and human activities.Winter and summer surveys in 2019 found that the ecological community of the Luhuitou coral reef flat was dominated by macroalgae and corals,respectively,contrasting with the conditions 10 years ago.The Luhuitou fringing reefs were sources of atmospheric CO_(2) in both seasons.In winter,the daily variation range of dissolved inorganic carbon(DIC)in Luhuitou coral reefs was up to 450μmol/kg,while that of total alkalinity(TA)was only 68μmol/kg.This indicated that the organic production was significantly higher than the calcification process during this period.The TA/DIC was approximately 0.15,which was less than half of that in healthy coral reefs;hence,photosynthesis-respiration processes were the most important factors controlling daily changes in the seawater carbonate system.The net community production(NCP)of the Luhuitou coral reef ecosystem in winter was as high as 47.65 mmol C/(m^(2)·h).While the net community calcification(NCC)was approximately 3.35 and-4.15 mmol CaCO_(3)/(m^(2)·h)during the daytime and nighttime respectively.Therefore,the NCC for the entire day was-21.9 mmol CaCO_(3)/(m^(2)·d),indicating a net autotrophic dissolved state.In summer,the acidification was enhanced by thunderstorms and heavy rain with the highest seawater partial pressure of CO_(2)(p CO_(2))and lowest pH T.Over the past 10 years,the increase rate of seawater p CO_(2) in Luhuitou reef was approximately 13.3μatm/a***,six times that of the open ocean,while the decrease rate of pH was approximately 0.0083/a,being five times that of the global ocean.These findings underscore the importance of protecting and restoring Luhuitou fringing reef,as well as similar reefs worldwide.展开更多
Coloration in rose(Rosa hybrida)petals is primarily determined by anthocyanin accumulation in vacuoles,and vacuolar acidification plays a central role in controlling the accumulation of this pigment.Nevertheless,the r...Coloration in rose(Rosa hybrida)petals is primarily determined by anthocyanin accumulation in vacuoles,and vacuolar acidification plays a central role in controlling the accumulation of this pigment.Nevertheless,the regulatory interplay between anthocyanin accumulation and tissue acidification processes remains somewhat unclear.The present study characterized an activator RhMYB114 and a repressor RhMYB16,which functioned synergistically in anthocyanin accumulation and tissue acidification in rose.Transforming tobacco and roses by overexpression,the introduction of RhMYB114 resulted in an increase in anthocyanin levels and a noticeable decrease in pH in the petal cells of both rose and tobacco,whereas RhMYB16 introduction led to inverse effects.To further clarify the underlying the regulatory mechanisms,the yeast two-hybrid(Y2H),bimolecular fluorescence complementation(BiFC)and dual-luciferase(LUC)were employed.The results showed that RhMYB16 competed with RhMYB114,bound to RhbHLH3 or RhbHLH33,and inhibited its ability to induce the expression of genes related to anthocyanin biosynthesis and acidification.Our findings revealed a feedback mechanism for the regulation of anthocyanin synthesis and tissue acidification involving RhMYB114,which stimulated the transcriptional expression of RhMYB16,whose encoded protein RhMYB16,in turn,negatively regulated the transcriptional expression of RhMYB114.Therefore,this study underscores the pivotal roles of the RhMYB114eRhMYB16 loop in regulating anthocyanin synthesis and tissue acidification,offering insights into metabolic manipulation to enhance the aesthetic appeal of roses.展开更多
Microbiologically driven acidic pollution of coal gangue has become amajor environmental problem in coal gangue dumps in coal mining areas.Addition of bactericides and sulphate reducing bacteria(SRB)is an effective me...Microbiologically driven acidic pollution of coal gangue has become amajor environmental problem in coal gangue dumps in coal mining areas.Addition of bactericides and sulphate reducing bacteria(SRB)is an effective means to control the acidic pollution of coal gangue,but their mechanism of action has not been fully investigated.By adding bactericide,SRB and bactericide-SRB to the newly produced coal gangue,respectively,the effects of these treatments on the microbial community structure were observed.Changes in pH and electrical conductivity(EC)of the gangue leaching solution,as well as themicrobial community composition and functional abundance on the gangue surface were analysed by leaching simulation experiments and 16S rRNA sequencing.The results showed that(1)the addition of bactericide-SRB was the most effective treatment to elevate pH before 8 d,while the addition of SRB performed best after 22 d(2)The addition of bactericide and SRB drastically changed the microbial community structure on the gangue surface.Simultaneous addition of both had the best inhibitory effect on pathogenic bacteria and Thiobacillus.(3)All three treatments promote higher abundance of genes related to nitrogen cycling,but reflected in different gene functions.Microorganisms with sulfate respiration function in the experimental group all showed different increases.The abundance of other sulfur cycle genes decreased substantially.However,Human Pathogens All had higher abundance than control check(CK)in each treatment,whichmay indicate that the addition of either bactericides or SRB increases the risk of microbial pathogenicity to humans.展开更多
Based on soil monitoring data in nine sites of Jinhu, Xuyi and Hongze counties on the south bank of Hongze Lake from 1982 to 2013, changes in soil p H, total nitrogen（TN） content, available phosphorus content, organ...Based on soil monitoring data in nine sites of Jinhu, Xuyi and Hongze counties on the south bank of Hongze Lake from 1982 to 2013, changes in soil p H, total nitrogen（TN） content, available phosphorus content, organic matter（OM）content and cation exchange capacity（CEC） were analyzed. The results show that due to excessive application of chemical fertilizer in soil on the south bank of Hongze Lake, soil p H reduced by about 2 on average, while TN content and available phosphorus content in soil increased by more than one time and 2-5 times respectively. Soil acidification caused by agricultural production was very serious. In addition, low soil p H resulted in serious loss of soil cation, so that soil CEC in2013 accounted for less than 50% of that in 1982 and affected mineral nutrient metabolism of crops. Therefore, application of calcium, potassium and trace-element fertilizer should be paid more attention to during agricultural production in future.展开更多
Effect of soil acidification on yield of late rice was studied and acid resistance of late rice varieties were compared with 23 late rice varieties as materials in Changsha County, Hunan Province. The results indicate...Effect of soil acidification on yield of late rice was studied and acid resistance of late rice varieties were compared with 23 late rice varieties as materials in Changsha County, Hunan Province. The results indicated that the difference in yield among varieties was obvious, yield in common field was among 5 226.6-9 202.1kg/hm^2, and yield in acidified field was among 3 643.2-7 714. 8 kg/hm^2. Compared with common field, yield of Yueyou 6135, Huayou 18, Jinyou 284 and Ⅱyou 46 increased by 3.24%-26.33% in acidified field, while yield of other varieties decreased by 2.04%-56.79% in acidified field. According to acidification sensitivity, Wufengyou T025, Jinchuyou No.148, Yueyou No.6135, Shenyou No.9586, Xiangfengyou No.103,Zhongyou No.288, Nongxiang No.18, Shanyou No.432, Ⅱ you No.6, and Zhong 9A/R10402 were sensitive to soil acidification; Wuyou No.308, Zhunliangyou No.608,Fengyuanyou No.227, Fengyou No.1167, Fengyuanyou No.299, T you No.272, and Zhong 9A/R9963 were moderately sensitive to soil acidification; Yueyou No.9113,Jinyou No.284, Shenyou No.9588, Huayou No.18, Ⅱ you No.46 and Ⅱ you No.3027 were slightly sensitive to soil acidification展开更多
The mechanisms for the effects of ammonium-based fertilizers on soil acidification in subtropical regions are not well understood. Two Ultisols collected from cropland and a tea garden in Anhui and Jiangxi Provinces i...The mechanisms for the effects of ammonium-based fertilizers on soil acidification in subtropical regions are not well understood. Two Ultisols collected from cropland and a tea garden in Anhui and Jiangxi Provinces in subtropical southern China, respectively, were used to study the effects of urea and （NH4）aSO4 on the nitrification and acidification of soils with incubation experiments. Nitrification occurred at very low pH with no N fertilizer added and led to lowering of the soil pH by 0.53 and 0.30 units for the soils from Jiangxi and Anhui, respectively. Addition of urea accelerated nitrification and soil acidification in both Ultisols; while nitrification was inhibited by the addition of （NH4）2SO4, and greater input of （NH4）2SO4 led to greater inhibition of nitrification. Ammonia-oxidizing bacteria （AOB） played an important role in nitrification in cropland soil under acidic conditions. Addition of urea increased the soil pH at the early stages of incubation due to hydrolysis and stimulated the increase in the AOB population, and thus accelerated nitrification and soil acidification. At the end of incubation, the pH of Ultisol from Jiangxi had decreased by 1.25, 1.54 and 1.84 units compared to maximum values for the treatments with 150, 300 and 400 mg/kg of urea-N added, respectively; the corresponding figures were 0.95, 1.25 and 1.69 for the Ultisol from Anhui. However, addition of （NH4）：SO4 inhibited the increase in the AOB population and thus inhibited nitrification and soil acidification. Soil pH for the treatments with 300 and 400 mg/kg of （NHn）2SOa-N remained almost constant during the incubation. AOB played an important role in nitrification of the cropland soil under acidic conditions. Addition of urea stimulated the increase in the AOB population and thus accelerated nitrification and soil acidification; while addition of （NH4）2SO4 inhibited the increase in the AOB population and thus inhibited nitrification.展开更多
Oceanic uptake of anthropogenic carbon dioxide results in a decrease in seawater pH, a process known as "ocean acidification". The pearl oyster Pinctada fucata, the noble scallop Chlamys nobilis, and the gre...Oceanic uptake of anthropogenic carbon dioxide results in a decrease in seawater pH, a process known as "ocean acidification". The pearl oyster Pinctada fucata, the noble scallop Chlamys nobilis, and the green-lipped mussel Perna viridis are species of economic and ecological importance along the southern coast of China. We evaluated the effects of seawater acidification on clearance, respiration, and excretion rates in these three species. The animals were reared in seawater at pH 8.1 (control), 7.7, or 7.4. The clearance rate was highest at pH 7.7 for P. fucata and at pH 8.1 for C. nobilis and P. viridis. The pH had little effecton the respiration rate of P. fucata and P. viridis. In contrast, the respiration rate was significantly lower atpH 7.4 in C. nobilis. The excretion rate was significantly lower at pH 7.4 than pH 8.1 for all species. Theresults indicate that the reduction in seawater pH likely affected the metabolic process (food intake, oxygenconsumption, and ammonia excretion) of these bivalves. Different species respond differently to seawateracidification. Further studies are needed to demonstrate the exact mechanisms for this effect and evaluateadaptability of these bivalves to future acidified oceans.展开更多
We studied the effect of pH （pH 5, 6, 7 and 8） on the hatching percentage, survival and reproduction of Artemia strains in Bohai Bay salt ponds. Strains included parthenogenetic Artemia from Bohai Bay （BHB）, Artem...We studied the effect of pH （pH 5, 6, 7 and 8） on the hatching percentage, survival and reproduction of Artemia strains in Bohai Bay salt ponds. Strains included parthenogenetic Artemia from Bohai Bay （BHB）, Artemiafranciscana from San Francisco Bay, and A. franciscana artificially produced in salt ponds in Vietnam. The latter was included as a potential inoculum for biological management of salt ponds. The hatching percentage of cysts after 24 h and the survival rate of the tested Artemia strains were significantly reduced when exposed to a culture medium at pH 5 for 18 d （P〈0.05）. The tolerance of Artemia to 48 h acid exposure varied with developmental stage, increasing in the following order： juvenile, nauplii, pre-adult, with maximum tolerance in adults. All strains of Artemia tested could not reproduce at pH 5. At pH levels from pH 6-8, a higher pH generally resulted in a shorter brood interval and enhanced ovoviviparity. Hence, we suggest that brine acidification has a negative impact on Artemia populations in the Bohai Bay saltworks. Inoculation of Artemia with either local parthenogenetic Artemia or exotic A. franeiscana should be feasible at pH 7-8.展开更多
Microwave heating contributes to coal fracturing and gas desorption. However, problems of low penetration depth, local overheating and fracture closure exist. Coal demineralisation by acids has advantages in coal unbl...Microwave heating contributes to coal fracturing and gas desorption. However, problems of low penetration depth, local overheating and fracture closure exist. Coal demineralisation by acids has advantages in coal unblocking and permeability improvement, while it is difficult for acid to enter microcracks.Microwave-asisted acidification may offer an alternative. In this work, XRD,^(1)H-NMR, and SEM were used to evaluate the effect of microwave-assisted acidification on the microstructure of coal. Results show that kaolinite, calcite, and dolomite can be dissolved by acid. After microwave irradiation, the graphitization of microcrystalline structure of carbon improves. Microwave-assisted acidification erodes minerals in coal and enhances the graphitization degree of microcrystalline structure. Compared to individual microwave irradiation or acidification, the pore volume and pore connectivity can be greatly enhanced by microwave-assisted acidification. The NMR permeability of coal increased by 28.05%. This study demonstrates the potential of microwave-assisted acidification for coalbed methane recovery.展开更多
INTRODUCTION Soil acidification due to acid deposition has been one of the major environmental prob-lems concerned by soil scientists and ecologists for the recent 20 years(van Breemen,1990).Soil acidification with a ...INTRODUCTION Soil acidification due to acid deposition has been one of the major environmental prob-lems concerned by soil scientists and ecologists for the recent 20 years(van Breemen,1990).Soil acidification with a marked pH decrease of forest soils within various time intervals hasbeen reported in Germany,Sweden,the Netherlands,Australia and the United展开更多
General pretreatment processes of ammonia stripping and phenols solvent extraction can reduce the concentration of toxic compounds of the coal gasification wastewater for the following biological treatment. However, s...General pretreatment processes of ammonia stripping and phenols solvent extraction can reduce the concentration of toxic compounds of the coal gasification wastewater for the following biological treatment. However, some emulsified coal tar still exists in the influent and many substances in coal tar are refractory and toxic to microorganisms. This study is mainly on the removal of emulsified coal tar by acidification demulsion. The experimental results show that the acidification process of the wastewater by pure hydrochloric acid can reduce the chemical oxygen demand （COD）, total organic carbon （TOC）, total phenolics and oil about 3.1%-11.3%, 6%-- 10.8%, 5.3%--8.6% and 25.2%--57.4% respectively with pH value in the range of 4 to 7. The analysis of molecular weight distribution indicates that compounds removed from the wastewater by this process are large molecular substances. The experiment also shows that the efficiency of COD removal in the demulsion process by different acids is different and the phosphoric acid is prominent. The preserved time of the wastewater also affects the efficiency of demulsion. Small amount low-cost solid additives including kaolin and diatomite can improve the rate of coal tar sedimentation and enhance the removal efficiency of organics in the phosphoric acidification process.展开更多
Two different kinds of black liquor from the papermaking industry were treated by acidification and reuse. The experimental parameters and conditions were discussed in detail. The experimental results indicated that t...Two different kinds of black liquor from the papermaking industry were treated by acidification and reuse. The experimental parameters and conditions were discussed in detail. The experimental results indicated that the treatment process mentioned in this article is an effective process for the treatment of black liquor from the papermaking industry. By the treatment, the solid materials in black liquor are transferred into two by products and the other components are reused or evaporated. Thus, no wastewater except some condensation water would be discharged in pulping process and the problem of pollution of black liquor would be effectively solved.展开更多
Ecological experiments were conducted to examine the effects of seawater containing elevated par- tial pressure of carbon dioxide （p CO2 800 × 10 -6 , 2 000 × 10 -6 , 5 000 × 10 -6 and 10 000 × 10...Ecological experiments were conducted to examine the effects of seawater containing elevated par- tial pressure of carbon dioxide （p CO2 800 × 10 -6 , 2 000 × 10 -6 , 5 000 × 10 -6 and 10 000 × 10 -6 ） on the survival and reproduction of female Acartia pacifica, Acartia spinicauda, Calanus sinicus and Centropages tenuiremis, which are the dominant copepods in the southern coastal waters of China. The results show that the effects of elevated p CO2 on the survival rates of copepods were species-specific. C. sinicus, which was a macro-copepod, had a higher survival rate （62.01%–71.96%） than the other three species （5.00%–26.67%） during the eight day exposure. The egg production rates of C. sinicus, A. spinicauda and C. tenuiremis were significantly inhibited by the increased p CO2 and the exposure time duration. There were significantly negative impacts on the egg hatching success of A. spinicauda and C. tenuiremis in the p CO2 2 000 × 10 -6 and 10 000 × 10 -6 groups, and, in addition, the exposure time had noticeably impacts on these rates too. This study indicates that the reproductive performances of copepods were sensitive to elevated p CO2 , and that the response of different copepod species to acidified seawater was different. Furthermore, the synergistic effects of seawater acidification and climate change or other pollutant stresses on organisms should be given more attention.展开更多
This study evaluated the impact of pig manure acidification on anaerobic treatment and composition of the fecal microbial community. According to the different chemical oxygen demand （COD） in the anaerobic treatment...This study evaluated the impact of pig manure acidification on anaerobic treatment and composition of the fecal microbial community. According to the different chemical oxygen demand （COD） in the anaerobic treatment processes, pig manure was diluted 4 times （×4）, 16 times （×16）, or 64 times （×64） and subjected to acidification. During the acidification process, pH, soluble chemical oxygen demand （SCOD）, volatile fatty acids （VFAs）, nitrogen （N）, phosphorus （P） and potassium （K） were determined along with microbial population dynamics. The pH of the three dilutions first declined, and then slowly increased. The total VFAs of x4 and xl6 dilutions peaked on day 15 and 20, respectively. The content of acetic acid, propanoic acid, butanoic acid and valeric acid of the × 4 dilution were 23.6, 11.4, 8.8 and 0.6 g/L respectively, and that of the xl6 dilution was 5.6, 2.3, 0.9 and 0.2 g/L respectively. Only acetic acid was detected in the ×64 dilution, and its level peaked on day 10. The results showed that the liquid pig manure was more suitable to enter the anaerobic methanogenic hioreactors after two weeks of acidification. During the acidification process, total P concentration increased during the first ten days, then dropped sharply, and rose again to a relatively high final concentration, while total N concentration rose initially and then declined. Based on the analysis of denaturing gradient gel electrophoresis （DGGE） and 16S rRNA gene clone library, we concluded that the acidification process reduced the number of pathogenic bacteria species in pig manure.展开更多
In this study, we evaluated the effects of CO_2-induced seawater acidification on fertilization, embryogenesis and early larval development in the sea urchin Glyptocidaris crenularis, that inhabits subtidal coastal ar...In this study, we evaluated the effects of CO_2-induced seawater acidification on fertilization, embryogenesis and early larval development in the sea urchin Glyptocidaris crenularis, that inhabits subtidal coastal areas in northern China. The range in seawater p H used in experiments was based on the projections of the Intergovernmental Panel on Climate Change(IPCC), to the year 2100. A natural seawater treatment(p H_(nbs) =7.98±0.03) and three laboratory-controlled acidified treatments(OA_1, ΔpH_(nbs) =-0.3 units; OA_2, ΔpH_(nbs) =-0.4 units; OA_3, ΔpH_(nbs) =-0.5 units) were used in experiments. Results show that:(1) there was a negative effect of seawater acidification on fertilization and on the percentage of abnormal fertilized eggs;(2) the size of early cleavage stage embryos decreased in a dose-dependent manner with decreasing p H;(3) both the hatching rate of blastulae and the survival rate of four-armed pluteus larvae decreased as pH declined;(4) larval abnormalities including asymmetrical development, changes in the length of skeletal elements, and corroded spicules were observed in all seawater acidified-treatments compared with the control. These data indicate that seawater acidification has a negative impact on the early development of G. crenularis, and supports the hypothesis that the response of echinoderms to ocean acidification(OA) varies among species. Further research is required to clarify the specific cellular mechanisms involved.展开更多
Soil acidification is a major threat to agricultural sustainability in tropical and subtropical regions.Biodegradable and environmentally friendly materials,such as calcium lignosulfonate(CaLS),calcium poly(aspartic a...Soil acidification is a major threat to agricultural sustainability in tropical and subtropical regions.Biodegradable and environmentally friendly materials,such as calcium lignosulfonate(CaLS),calcium poly(aspartic acid)(PASP-Ca),and calcium polyγ-glutamic acid(γ-PGA-Ca),are known to effectively ameliorate soil acidity.However,their effectiveness in inhibiting soil acidification has not been studied.This study aimed to evaluate the effect of CaLS,PASP-Ca,andγ-PGA-Ca on the resistance of soil toward acidification as directly and indirectly(i.e.,via nitrification)caused by the application of HNO_(3)and urea,respectively.For comparison,Ca(OH)_(2)and lignin were used as the inorganic and organic controls,respectively.Among the materials,γ-PGA-Ca drove the substantial improvements in the pH buffering capacity(pHBC)of the soil and exhibited the greatest potential in inhibiting HNO_(3)-induced soil acidification via protonation of carboxyl,complexing with Al~(3+),and cation exchange processes.Under acidification induced by urea,CaLS was the optimal one in inhibiting acidification and increasing exchangeable acidity during incubation.Furthermore,the sharp reduction in the population sizes of ammonia-oxidizing bacteria(AOB)and ammonia-oxidizing archaea(AOA)confirmed the inhibition of nitrification via CaLS application.Therefore,compared to improving soil pHBC,CaLS may play a more important role in suppressing indirect acidification.Overall,γ-PGA-Ca was superior to PASP-Ca and CaLS in enhancing the soil pHBC and the its resistance to acidification induced by HNO_(3) addition,whereas CaLS was the best at suppressing urea-driven soil acidification by inhibiting nitrification.In conclusion,these results provide a reference for inhibiting soil re-acidification in intensive agricultural systems.展开更多
The cost-effective treatment of activated sludge that is generated by refining petroleum is a challenging industrial problem.In this study, semi-continuous stirred tank reactors(CSTRs) containing petroleum refinery ex...The cost-effective treatment of activated sludge that is generated by refining petroleum is a challenging industrial problem.In this study, semi-continuous stirred tank reactors(CSTRs) containing petroleum refinery excess activated sludge(PREAS)were used to comparatively investigate hydrolysis and acidification rates, after the addition of heneicosane(C_(21)H_(44))(R1)and 1-phenylnaphthalene(C16 H12)(R2) to different and individual reactors. Operation of the reactors using a sludge retention time(SRT) of 6 days and a pH of 5.0, resulted in the maintenance of stable biological activity as determined by soluble chemical oxygen demand(SCOD), volatile fatty acids(VFAs) production and oil removal efficiency. The optimum conditions for hydrogen production include a SRT of 8 days, at pH 6.5. Under these conditions, hydrogen production rates in the control containing only PREAS were 1567 mL/L(R0), compared with 1365 mL/L in Rl and 1454 mL/L-PREAS in R2.Coprothermobacter, Fervidobacterium, Caldisericum and Tepidiphilus were the dominant bacterial genera that have the potential to degrade petroleum compounds and generate VFAs. This study has shown that high concentrations of heneicosane and 1-phenylnaphthalene did not inhibit the hydrolytic acidification of PREAS.展开更多
Effects of sludge age on volatile fatty acids (VFAs) production and Phosphorus (P) release during anaerobic acidification of waste activated sludge (WAS) were investigated.Sequencing batch reactors (SBR) fed with simu...Effects of sludge age on volatile fatty acids (VFAs) production and Phosphorus (P) release during anaerobic acidification of waste activated sludge (WAS) were investigated.Sequencing batch reactors (SBR) fed with simulating domestic sewage were applied to produce WAS of different sludge ages,and batch tests were used for anaerobic acidification.The maximum dissolved total organic carbon,release of PO_(4)^(3+)-P,and accumulation of acetate (C2),propionate (C3),butyrate (C4),and valerate (C5) decreased by 56.2%,55.8%,52.6%,43.7%,82.4%and 84.8%,respectively,as the sludge age of WAS increased from 5 to 40 days.Limited degradation of protein played a dominating role in decreasing DTOC and VFAs production.Moreover,the increase in molecular weight of organics and organic nitrogen content in the supernatant after acidification suggested that the refractory protein in WAS increased as sludge age extended.Although the production of C2,C3,C4,and C5 from WAS decreased as the sludge age increased,the proportions of C2 and C3 in VFAs increased,which might be due to the declined production of C5 from protein and the faded genus Dechlorobacter.Keeping sludge age of WAS at a relatively low level (<10 days) is more appropriate for anaerobic acidification of WAS as internal carbon sources and P resource.展开更多
基金supported by the National Natural Science Foundation of China,No.82201582(to QT)Scientific and Technological Research Program of Chongqing Municipal Education Commission,No.KJQN202200457(to QT)+3 种基金General Project of Changqing Natural Science Foundation,No.cstc2021jcyjmsxmX0442(to ZL)CQMU Program for Youth Innovation in Future Medicine,No.W0044(to ZD and GH)Direct Research Project for PhD of Chongqing,No.CSTB2022BSXM-JCX0051(to ZL)the Project of the Top-Notch Talent Cultivation Program For the Graduate Students of Chongqing Medical University,No.BJRC202310(to CG)。
文摘Recent studies have suggested that abnormal acidification of lysosomes induces autophagic accumulation of amyloid-βin neurons,which is a key step in senile plaque formation.Therefore,resto ring normal lysosomal function and rebalancing lysosomal acidification in neurons in the brain may be a new treatment strategy for Alzheimer's disease.Microtubule acetylation/deacetylation plays a central role in lysosomal acidification.Here,we show that inhibiting the classic microtubule deacetylase histone deacetylase 6 with an histone deacetylase 6 shRNA or thehistone deacetylase 6 inhibitor valproic acid promoted lysosomal reacidification by modulating V-ATPase assembly in Alzheimer's disease.Fu rthermore,we found that treatment with valproic acid markedly enhanced autophagy.promoted clearance of amyloid-βaggregates,and ameliorated cognitive deficits in a mouse model of Alzheimer's disease.Our findings demonstrate a previously unknown neuroprotective mechanism in Alzheimer's disease,in which histone deacetylase 6 inhibition by valproic acid increases V-ATPase assembly and lysosomal acidification.
基金Supported by the National Key Research and Development Program of China(Nos.2021YFC3100500,2022YFC3103602,2021YFF0502800)the National Natural Science Foundation of China(No.U23A2035)+3 种基金the Science and Technology Planning Project of Guangdong Province,China(No.2023B1212060047)the State Key Laboratory of Tropical Oceanography,South China Sea Institute of Oceanology,Chinese Academy of Sciences(No.LTO1919)the Visiting Fellowship Program of the State Key Laboratory of Marine Environmental Science,Xiamen University(No.MELRS1914)the Hainan Province Key R&D Program(No.ZDYF2023SHFZ131)。
文摘Global coral reef ecosystems have been severely degraded due to the combined effects of climate change and human activities.Changes in the seawater carbonate system of coral reef ecosystems can reflect their status and their responses to the impacts of climate change and human activities.Winter and summer surveys in 2019 found that the ecological community of the Luhuitou coral reef flat was dominated by macroalgae and corals,respectively,contrasting with the conditions 10 years ago.The Luhuitou fringing reefs were sources of atmospheric CO_(2) in both seasons.In winter,the daily variation range of dissolved inorganic carbon(DIC)in Luhuitou coral reefs was up to 450μmol/kg,while that of total alkalinity(TA)was only 68μmol/kg.This indicated that the organic production was significantly higher than the calcification process during this period.The TA/DIC was approximately 0.15,which was less than half of that in healthy coral reefs;hence,photosynthesis-respiration processes were the most important factors controlling daily changes in the seawater carbonate system.The net community production(NCP)of the Luhuitou coral reef ecosystem in winter was as high as 47.65 mmol C/(m^(2)·h).While the net community calcification(NCC)was approximately 3.35 and-4.15 mmol CaCO_(3)/(m^(2)·h)during the daytime and nighttime respectively.Therefore,the NCC for the entire day was-21.9 mmol CaCO_(3)/(m^(2)·d),indicating a net autotrophic dissolved state.In summer,the acidification was enhanced by thunderstorms and heavy rain with the highest seawater partial pressure of CO_(2)(p CO_(2))and lowest pH T.Over the past 10 years,the increase rate of seawater p CO_(2) in Luhuitou reef was approximately 13.3μatm/a***,six times that of the open ocean,while the decrease rate of pH was approximately 0.0083/a,being five times that of the global ocean.These findings underscore the importance of protecting and restoring Luhuitou fringing reef,as well as similar reefs worldwide.
基金supported by the National Natural Science Foundation of China(Grant No.32171851)Natural Science Foundation of Zhejiang(Grant No.LZ23C160003)the Fundamental Research Funds for the Zhejiang A&F University(Grant No.2016FR033)。
文摘Coloration in rose(Rosa hybrida)petals is primarily determined by anthocyanin accumulation in vacuoles,and vacuolar acidification plays a central role in controlling the accumulation of this pigment.Nevertheless,the regulatory interplay between anthocyanin accumulation and tissue acidification processes remains somewhat unclear.The present study characterized an activator RhMYB114 and a repressor RhMYB16,which functioned synergistically in anthocyanin accumulation and tissue acidification in rose.Transforming tobacco and roses by overexpression,the introduction of RhMYB114 resulted in an increase in anthocyanin levels and a noticeable decrease in pH in the petal cells of both rose and tobacco,whereas RhMYB16 introduction led to inverse effects.To further clarify the underlying the regulatory mechanisms,the yeast two-hybrid(Y2H),bimolecular fluorescence complementation(BiFC)and dual-luciferase(LUC)were employed.The results showed that RhMYB16 competed with RhMYB114,bound to RhbHLH3 or RhbHLH33,and inhibited its ability to induce the expression of genes related to anthocyanin biosynthesis and acidification.Our findings revealed a feedback mechanism for the regulation of anthocyanin synthesis and tissue acidification involving RhMYB114,which stimulated the transcriptional expression of RhMYB16,whose encoded protein RhMYB16,in turn,negatively regulated the transcriptional expression of RhMYB114.Therefore,this study underscores the pivotal roles of the RhMYB114eRhMYB16 loop in regulating anthocyanin synthesis and tissue acidification,offering insights into metabolic manipulation to enhance the aesthetic appeal of roses.
文摘Microbiologically driven acidic pollution of coal gangue has become amajor environmental problem in coal gangue dumps in coal mining areas.Addition of bactericides and sulphate reducing bacteria(SRB)is an effective means to control the acidic pollution of coal gangue,but their mechanism of action has not been fully investigated.By adding bactericide,SRB and bactericide-SRB to the newly produced coal gangue,respectively,the effects of these treatments on the microbial community structure were observed.Changes in pH and electrical conductivity(EC)of the gangue leaching solution,as well as themicrobial community composition and functional abundance on the gangue surface were analysed by leaching simulation experiments and 16S rRNA sequencing.The results showed that(1)the addition of bactericide-SRB was the most effective treatment to elevate pH before 8 d,while the addition of SRB performed best after 22 d(2)The addition of bactericide and SRB drastically changed the microbial community structure on the gangue surface.Simultaneous addition of both had the best inhibitory effect on pathogenic bacteria and Thiobacillus.(3)All three treatments promote higher abundance of genes related to nitrogen cycling,but reflected in different gene functions.Microorganisms with sulfate respiration function in the experimental group all showed different increases.The abundance of other sulfur cycle genes decreased substantially.However,Human Pathogens All had higher abundance than control check(CK)in each treatment,whichmay indicate that the addition of either bactericides or SRB increases the risk of microbial pathogenicity to humans.
基金Supported by the Surface Project of Natural Science Research for Higher Education in Jiangsu Province(13KJB210001)Innovation Planning Project for University Students in Jiangsu Province(201310323040Y)Key Technology R&D Program of Huai'an City,Jiangsu Province(SN13049)~~
文摘Based on soil monitoring data in nine sites of Jinhu, Xuyi and Hongze counties on the south bank of Hongze Lake from 1982 to 2013, changes in soil p H, total nitrogen（TN） content, available phosphorus content, organic matter（OM）content and cation exchange capacity（CEC） were analyzed. The results show that due to excessive application of chemical fertilizer in soil on the south bank of Hongze Lake, soil p H reduced by about 2 on average, while TN content and available phosphorus content in soil increased by more than one time and 2-5 times respectively. Soil acidification caused by agricultural production was very serious. In addition, low soil p H resulted in serious loss of soil cation, so that soil CEC in2013 accounted for less than 50% of that in 1982 and affected mineral nutrient metabolism of crops. Therefore, application of calcium, potassium and trace-element fertilizer should be paid more attention to during agricultural production in future.
基金Supported by National Nature Science Foundation of China(31171494)Projects in the National Science&Technology Pillar Program(2011BAD16B01,2012BAD04B10-01,2013BAD07B11-02)~~
文摘Effect of soil acidification on yield of late rice was studied and acid resistance of late rice varieties were compared with 23 late rice varieties as materials in Changsha County, Hunan Province. The results indicated that the difference in yield among varieties was obvious, yield in common field was among 5 226.6-9 202.1kg/hm^2, and yield in acidified field was among 3 643.2-7 714. 8 kg/hm^2. Compared with common field, yield of Yueyou 6135, Huayou 18, Jinyou 284 and Ⅱyou 46 increased by 3.24%-26.33% in acidified field, while yield of other varieties decreased by 2.04%-56.79% in acidified field. According to acidification sensitivity, Wufengyou T025, Jinchuyou No.148, Yueyou No.6135, Shenyou No.9586, Xiangfengyou No.103,Zhongyou No.288, Nongxiang No.18, Shanyou No.432, Ⅱ you No.6, and Zhong 9A/R10402 were sensitive to soil acidification; Wuyou No.308, Zhunliangyou No.608,Fengyuanyou No.227, Fengyou No.1167, Fengyuanyou No.299, T you No.272, and Zhong 9A/R9963 were moderately sensitive to soil acidification; Yueyou No.9113,Jinyou No.284, Shenyou No.9588, Huayou No.18, Ⅱ you No.46 and Ⅱ you No.3027 were slightly sensitive to soil acidification
基金supported by the National Natural Science Foundation of China (No. 30821140538)the National Key Technology R&D Program of China (No.2009BADC6B02)
文摘The mechanisms for the effects of ammonium-based fertilizers on soil acidification in subtropical regions are not well understood. Two Ultisols collected from cropland and a tea garden in Anhui and Jiangxi Provinces in subtropical southern China, respectively, were used to study the effects of urea and （NH4）aSO4 on the nitrification and acidification of soils with incubation experiments. Nitrification occurred at very low pH with no N fertilizer added and led to lowering of the soil pH by 0.53 and 0.30 units for the soils from Jiangxi and Anhui, respectively. Addition of urea accelerated nitrification and soil acidification in both Ultisols; while nitrification was inhibited by the addition of （NH4）2SO4, and greater input of （NH4）2SO4 led to greater inhibition of nitrification. Ammonia-oxidizing bacteria （AOB） played an important role in nitrification in cropland soil under acidic conditions. Addition of urea increased the soil pH at the early stages of incubation due to hydrolysis and stimulated the increase in the AOB population, and thus accelerated nitrification and soil acidification. At the end of incubation, the pH of Ultisol from Jiangxi had decreased by 1.25, 1.54 and 1.84 units compared to maximum values for the treatments with 150, 300 and 400 mg/kg of urea-N added, respectively; the corresponding figures were 0.95, 1.25 and 1.69 for the Ultisol from Anhui. However, addition of （NH4）：SO4 inhibited the increase in the AOB population and thus inhibited nitrification and soil acidification. Soil pH for the treatments with 300 and 400 mg/kg of （NHn）2SOa-N remained almost constant during the incubation. AOB played an important role in nitrification of the cropland soil under acidic conditions. Addition of urea stimulated the increase in the AOB population and thus accelerated nitrification and soil acidification; while addition of （NH4）2SO4 inhibited the increase in the AOB population and thus inhibited nitrification.
基金Supported by National Natural Science Foundation of China (No.41006090)the Knowledge Innovation Program of Chinese Academy of Sciences (No. KZCX2-YW-Q07-03)the National High Technology Research and Development Program of China (863 Program) (No.2006AA10A409)
文摘Oceanic uptake of anthropogenic carbon dioxide results in a decrease in seawater pH, a process known as "ocean acidification". The pearl oyster Pinctada fucata, the noble scallop Chlamys nobilis, and the green-lipped mussel Perna viridis are species of economic and ecological importance along the southern coast of China. We evaluated the effects of seawater acidification on clearance, respiration, and excretion rates in these three species. The animals were reared in seawater at pH 8.1 (control), 7.7, or 7.4. The clearance rate was highest at pH 7.7 for P. fucata and at pH 8.1 for C. nobilis and P. viridis. The pH had little effecton the respiration rate of P. fucata and P. viridis. In contrast, the respiration rate was significantly lower atpH 7.4 in C. nobilis. The excretion rate was significantly lower at pH 7.4 than pH 8.1 for all species. Theresults indicate that the reduction in seawater pH likely affected the metabolic process (food intake, oxygenconsumption, and ammonia excretion) of these bivalves. Different species respond differently to seawateracidification. Further studies are needed to demonstrate the exact mechanisms for this effect and evaluateadaptability of these bivalves to future acidified oceans.
基金Supported by the International Cooperation Research Program of the Ministry of Science&Technology of China(No.2010DFA32300)the Pilot Project for International Cooperation"Aquaculture in Hebei and Shandong Provinces"funded by the Province of East-Flanders,Belgiumthe Nature Science Foundation of Tianjin(No.13JCZDJC28700)
文摘We studied the effect of pH （pH 5, 6, 7 and 8） on the hatching percentage, survival and reproduction of Artemia strains in Bohai Bay salt ponds. Strains included parthenogenetic Artemia from Bohai Bay （BHB）, Artemiafranciscana from San Francisco Bay, and A. franciscana artificially produced in salt ponds in Vietnam. The latter was included as a potential inoculum for biological management of salt ponds. The hatching percentage of cysts after 24 h and the survival rate of the tested Artemia strains were significantly reduced when exposed to a culture medium at pH 5 for 18 d （P〈0.05）. The tolerance of Artemia to 48 h acid exposure varied with developmental stage, increasing in the following order： juvenile, nauplii, pre-adult, with maximum tolerance in adults. All strains of Artemia tested could not reproduce at pH 5. At pH levels from pH 6-8, a higher pH generally resulted in a shorter brood interval and enhanced ovoviviparity. Hence, we suggest that brine acidification has a negative impact on Artemia populations in the Bohai Bay saltworks. Inoculation of Artemia with either local parthenogenetic Artemia or exotic A. franeiscana should be feasible at pH 7-8.
基金supported by the National Natural Science Foundation of China (Nos. 52274195, 52274196, 51904103, and 52174180)the Science and Technology Innovation Program of Hunan Province (No. 2022RC1178)+1 种基金Hunan Provincial Natural Science Foundation of China (Nos. 2022JJ20024, and 2021JJ30254)Scientific Research Foundation of Hunan Provincial Education Department (No. 21B0465)。
文摘Microwave heating contributes to coal fracturing and gas desorption. However, problems of low penetration depth, local overheating and fracture closure exist. Coal demineralisation by acids has advantages in coal unblocking and permeability improvement, while it is difficult for acid to enter microcracks.Microwave-asisted acidification may offer an alternative. In this work, XRD,^(1)H-NMR, and SEM were used to evaluate the effect of microwave-assisted acidification on the microstructure of coal. Results show that kaolinite, calcite, and dolomite can be dissolved by acid. After microwave irradiation, the graphitization of microcrystalline structure of carbon improves. Microwave-assisted acidification erodes minerals in coal and enhances the graphitization degree of microcrystalline structure. Compared to individual microwave irradiation or acidification, the pore volume and pore connectivity can be greatly enhanced by microwave-assisted acidification. The NMR permeability of coal increased by 28.05%. This study demonstrates the potential of microwave-assisted acidification for coalbed methane recovery.
基金Project supported by the National Natural Science Foundation of China.
文摘INTRODUCTION Soil acidification due to acid deposition has been one of the major environmental prob-lems concerned by soil scientists and ecologists for the recent 20 years(van Breemen,1990).Soil acidification with a marked pH decrease of forest soils within various time intervals hasbeen reported in Germany,Sweden,the Netherlands,Australia and the United
文摘General pretreatment processes of ammonia stripping and phenols solvent extraction can reduce the concentration of toxic compounds of the coal gasification wastewater for the following biological treatment. However, some emulsified coal tar still exists in the influent and many substances in coal tar are refractory and toxic to microorganisms. This study is mainly on the removal of emulsified coal tar by acidification demulsion. The experimental results show that the acidification process of the wastewater by pure hydrochloric acid can reduce the chemical oxygen demand （COD）, total organic carbon （TOC）, total phenolics and oil about 3.1%-11.3%, 6%-- 10.8%, 5.3%--8.6% and 25.2%--57.4% respectively with pH value in the range of 4 to 7. The analysis of molecular weight distribution indicates that compounds removed from the wastewater by this process are large molecular substances. The experiment also shows that the efficiency of COD removal in the demulsion process by different acids is different and the phosphoric acid is prominent. The preserved time of the wastewater also affects the efficiency of demulsion. Small amount low-cost solid additives including kaolin and diatomite can improve the rate of coal tar sedimentation and enhance the removal efficiency of organics in the phosphoric acidification process.
文摘Two different kinds of black liquor from the papermaking industry were treated by acidification and reuse. The experimental parameters and conditions were discussed in detail. The experimental results indicated that the treatment process mentioned in this article is an effective process for the treatment of black liquor from the papermaking industry. By the treatment, the solid materials in black liquor are transferred into two by products and the other components are reused or evaporated. Thus, no wastewater except some condensation water would be discharged in pulping process and the problem of pollution of black liquor would be effectively solved.
基金The State Oceanic Administration Foundation of China under contract No.200805029
文摘Ecological experiments were conducted to examine the effects of seawater containing elevated par- tial pressure of carbon dioxide （p CO2 800 × 10 -6 , 2 000 × 10 -6 , 5 000 × 10 -6 and 10 000 × 10 -6 ） on the survival and reproduction of female Acartia pacifica, Acartia spinicauda, Calanus sinicus and Centropages tenuiremis, which are the dominant copepods in the southern coastal waters of China. The results show that the effects of elevated p CO2 on the survival rates of copepods were species-specific. C. sinicus, which was a macro-copepod, had a higher survival rate （62.01%–71.96%） than the other three species （5.00%–26.67%） during the eight day exposure. The egg production rates of C. sinicus, A. spinicauda and C. tenuiremis were significantly inhibited by the increased p CO2 and the exposure time duration. There were significantly negative impacts on the egg hatching success of A. spinicauda and C. tenuiremis in the p CO2 2 000 × 10 -6 and 10 000 × 10 -6 groups, and, in addition, the exposure time had noticeably impacts on these rates too. This study indicates that the reproductive performances of copepods were sensitive to elevated p CO2 , and that the response of different copepod species to acidified seawater was different. Furthermore, the synergistic effects of seawater acidification and climate change or other pollutant stresses on organisms should be given more attention.
基金supported by the National Key Technology Research and Development Program of China during the 11th Five-Year Plan Period (No. 2008BADC4B01,2008BADC4B17)the National Water Pollution Control and Management Special Project of China (No.2008ZX07209-003)
文摘This study evaluated the impact of pig manure acidification on anaerobic treatment and composition of the fecal microbial community. According to the different chemical oxygen demand （COD） in the anaerobic treatment processes, pig manure was diluted 4 times （×4）, 16 times （×16）, or 64 times （×64） and subjected to acidification. During the acidification process, pH, soluble chemical oxygen demand （SCOD）, volatile fatty acids （VFAs）, nitrogen （N）, phosphorus （P） and potassium （K） were determined along with microbial population dynamics. The pH of the three dilutions first declined, and then slowly increased. The total VFAs of x4 and xl6 dilutions peaked on day 15 and 20, respectively. The content of acetic acid, propanoic acid, butanoic acid and valeric acid of the × 4 dilution were 23.6, 11.4, 8.8 and 0.6 g/L respectively, and that of the xl6 dilution was 5.6, 2.3, 0.9 and 0.2 g/L respectively. Only acetic acid was detected in the ×64 dilution, and its level peaked on day 10. The results showed that the liquid pig manure was more suitable to enter the anaerobic methanogenic hioreactors after two weeks of acidification. During the acidification process, total P concentration increased during the first ten days, then dropped sharply, and rose again to a relatively high final concentration, while total N concentration rose initially and then declined. Based on the analysis of denaturing gradient gel electrophoresis （DGGE） and 16S rRNA gene clone library, we concluded that the acidification process reduced the number of pathogenic bacteria species in pig manure.
基金Supported by the National Natural Science Foundation of China(No.41206128)the Program for Liaoning Excellent Talents in University(No.LJQ2013079)the National High Technology Research and Development Program of China(863 Program)(No.2012AA10A412)
文摘In this study, we evaluated the effects of CO_2-induced seawater acidification on fertilization, embryogenesis and early larval development in the sea urchin Glyptocidaris crenularis, that inhabits subtidal coastal areas in northern China. The range in seawater p H used in experiments was based on the projections of the Intergovernmental Panel on Climate Change(IPCC), to the year 2100. A natural seawater treatment(p H_(nbs) =7.98±0.03) and three laboratory-controlled acidified treatments(OA_1, ΔpH_(nbs) =-0.3 units; OA_2, ΔpH_(nbs) =-0.4 units; OA_3, ΔpH_(nbs) =-0.5 units) were used in experiments. Results show that:(1) there was a negative effect of seawater acidification on fertilization and on the percentage of abnormal fertilized eggs;(2) the size of early cleavage stage embryos decreased in a dose-dependent manner with decreasing p H;(3) both the hatching rate of blastulae and the survival rate of four-armed pluteus larvae decreased as pH declined;(4) larval abnormalities including asymmetrical development, changes in the length of skeletal elements, and corroded spicules were observed in all seawater acidified-treatments compared with the control. These data indicate that seawater acidification has a negative impact on the early development of G. crenularis, and supports the hypothesis that the response of echinoderms to ocean acidification(OA) varies among species. Further research is required to clarify the specific cellular mechanisms involved.
基金supported by the Major project of Ministry of Agriculture and Rural Affairs of the People’s Republic of China(No.NK2022180401)the major project of Ministry of Agriculture and Rural Affairs of the People’s Republic of China(No.NK2022180404)。
文摘Soil acidification is a major threat to agricultural sustainability in tropical and subtropical regions.Biodegradable and environmentally friendly materials,such as calcium lignosulfonate(CaLS),calcium poly(aspartic acid)(PASP-Ca),and calcium polyγ-glutamic acid(γ-PGA-Ca),are known to effectively ameliorate soil acidity.However,their effectiveness in inhibiting soil acidification has not been studied.This study aimed to evaluate the effect of CaLS,PASP-Ca,andγ-PGA-Ca on the resistance of soil toward acidification as directly and indirectly(i.e.,via nitrification)caused by the application of HNO_(3)and urea,respectively.For comparison,Ca(OH)_(2)and lignin were used as the inorganic and organic controls,respectively.Among the materials,γ-PGA-Ca drove the substantial improvements in the pH buffering capacity(pHBC)of the soil and exhibited the greatest potential in inhibiting HNO_(3)-induced soil acidification via protonation of carboxyl,complexing with Al~(3+),and cation exchange processes.Under acidification induced by urea,CaLS was the optimal one in inhibiting acidification and increasing exchangeable acidity during incubation.Furthermore,the sharp reduction in the population sizes of ammonia-oxidizing bacteria(AOB)and ammonia-oxidizing archaea(AOA)confirmed the inhibition of nitrification via CaLS application.Therefore,compared to improving soil pHBC,CaLS may play a more important role in suppressing indirect acidification.Overall,γ-PGA-Ca was superior to PASP-Ca and CaLS in enhancing the soil pHBC and the its resistance to acidification induced by HNO_(3) addition,whereas CaLS was the best at suppressing urea-driven soil acidification by inhibiting nitrification.In conclusion,these results provide a reference for inhibiting soil re-acidification in intensive agricultural systems.
基金financially supported by Natural Science Foundation of China (No. 21776307)Science and Technology Major Project of China (No. 2016zx05040)Science Foundation of China University of Petroleum, Beijing (No. 2462018BJB001)
文摘The cost-effective treatment of activated sludge that is generated by refining petroleum is a challenging industrial problem.In this study, semi-continuous stirred tank reactors(CSTRs) containing petroleum refinery excess activated sludge(PREAS)were used to comparatively investigate hydrolysis and acidification rates, after the addition of heneicosane(C_(21)H_(44))(R1)and 1-phenylnaphthalene(C16 H12)(R2) to different and individual reactors. Operation of the reactors using a sludge retention time(SRT) of 6 days and a pH of 5.0, resulted in the maintenance of stable biological activity as determined by soluble chemical oxygen demand(SCOD), volatile fatty acids(VFAs) production and oil removal efficiency. The optimum conditions for hydrogen production include a SRT of 8 days, at pH 6.5. Under these conditions, hydrogen production rates in the control containing only PREAS were 1567 mL/L(R0), compared with 1365 mL/L in Rl and 1454 mL/L-PREAS in R2.Coprothermobacter, Fervidobacterium, Caldisericum and Tepidiphilus were the dominant bacterial genera that have the potential to degrade petroleum compounds and generate VFAs. This study has shown that high concentrations of heneicosane and 1-phenylnaphthalene did not inhibit the hydrolytic acidification of PREAS.
基金supported by the National Natural Science Foundation of China(Grant No.52000139)the China Post-doctoral Science Foundation(Grant number 2020M680058).
文摘Effects of sludge age on volatile fatty acids (VFAs) production and Phosphorus (P) release during anaerobic acidification of waste activated sludge (WAS) were investigated.Sequencing batch reactors (SBR) fed with simulating domestic sewage were applied to produce WAS of different sludge ages,and batch tests were used for anaerobic acidification.The maximum dissolved total organic carbon,release of PO_(4)^(3+)-P,and accumulation of acetate (C2),propionate (C3),butyrate (C4),and valerate (C5) decreased by 56.2%,55.8%,52.6%,43.7%,82.4%and 84.8%,respectively,as the sludge age of WAS increased from 5 to 40 days.Limited degradation of protein played a dominating role in decreasing DTOC and VFAs production.Moreover,the increase in molecular weight of organics and organic nitrogen content in the supernatant after acidification suggested that the refractory protein in WAS increased as sludge age extended.Although the production of C2,C3,C4,and C5 from WAS decreased as the sludge age increased,the proportions of C2 and C3 in VFAs increased,which might be due to the declined production of C5 from protein and the faded genus Dechlorobacter.Keeping sludge age of WAS at a relatively low level (<10 days) is more appropriate for anaerobic acidification of WAS as internal carbon sources and P resource.
