Stability of expanded granular sludge bed process for terylene artificial silk printing and dyeing wastewater treatment

Terylene artificial silk printing and dyeing wastewater(TPD wastewater), containing averaged 710 mg/L terephthalic acid(TA) as the main carbon source and the character pollutant, was subjected to expanded granular sludge bed(EGSB) process. The stability of the EGSB process was firstly conducted by laboratory experiment. TA ionization was the predominated factor influencing the acid-base balance of the system. High concentration of TA in wastewater resulted in sufficient buffering capacity to neutralize the volatile fatty acids(VFA) generated from substrate degradation and provided strong base for anaerobic system to resist the pH decrease below 6.5. VFA and UFA caused almost no inhibition on the anaerobic process and biogas production except that pH was below 6.35 and VFA was at its maximum value. Along with the granulating of the activated sludge, the efficiency of organic removal and production rate of biogas increased gradually and became more stable. After start-up, the efficiency of COD removal increased to 57%—64%, pH stabilized in a range of 7.99—8.04, and production rate of biogas was relatively high and stable. Sludge granulating, suitable influent of pH and loading were responsible for the EGSB stability. The variation of VFA concentration only resulted in neglectable rebound of pH, and the inhibition from VFA could be ignored in EGSB. The EGSB reactor was stable for TPD wastewater treatment.

Inhibitory Effects of Fumigation and Anaerobic Treatments of Citronellal,Wintergreen Oil and Their Composite Essence on Penicillium citrinum

[Objectives]The research was to explore the antifungal effects of citronellal,wintergreen oil and their composite essence on Penicillium citrinum.[Methods]The inhibition zones of citronellal,wintergreen oil and their composite essence against P.citrinum were determined by disk diffusion method,and the growth of inhibition zone plate was observed.The fumigation fungicidal rate of fungi-bearing rice paper within 7 d was determined by plate counting method.[Results]Citronellal had strong antifungal effect,and wintergreen oil could slow down the growth rate of P.citrinum.The combination of citronellal and wintergreen oil had a synergistic effect.As fumigants,both citronellal and composite essence had fungicidal rates up to 100%within 7 d.Combined with anaerobic treatments,all the three essential oils could improve the fungicidal efficiency.The adsorbent in deoxidizing agent would adsorb the essential oils,so that their fumigation had a certain slow release effect.[Conclusions]This study can provide a more friendly and efficient method for the prevention and control of cultural relics mold.

Stream Monitoring and Preliminary Co-Treatment of Acid Mine Drainage and Municipal Wastewater along Dunkard Creek Area

This study investigated coal-mine drainage(AMD)and municipal wastewater(MWW)contaminant concentrations and conducted the combined treatment in phases I and II:phase I,evaluating the effects of mixing the two based on the extent of acid neutralization and metals removal;phase II:conducting anaerobic batch reactor treatment of AMD and MWW under varying COD/sulfate ratios(0.04-5.0).In phase I,acid mine drainage water quality conditions are as follows:pH 4.5,acidity 467.5 mg/L as CaCO3,alkalinity 96.0 mg/L as CaCO3,Cl-11.8 mg/L,SO42-1722 mg/L,TDS 2757.5 mg/L,TSS 9.8 mg/L,BOD 14.7 mg/L,Fe 138.1 mg/L,Mg 110.8 mg/L.Mn 7.5 mg/L,Al 8.1 mg/L,Na 114.2 mg/L,and Ca 233.5 mg/L.Results of the mixing experiments indicated significant removal of selected metals(Fe 85~98%,Mg 0~65%,Mn 63~89%,Al 98~99%,Na 0~30%),acidity(77~95%)from the mine water and pH was raised to above 6.3.The Phase II results suggested under the wide range of COD/sulfate ratios,COD and sulfate removal varied from 37.4%-100%and 0%-93.5%respectively.During biological treatment,alkalinity was generated which leads to pH increase to around 7.6-8.5.The results suggested feasibility of the proposed technology for co-treatment of AMD and MWW.A conceptual design of co-treatment system which is expected to remove a matrix of pollutants has been provided to utilize all the locally available water resources to achieve the optimum treatment efficiency.The technology also offers an opportunity to significantly reduce capital and operating costs compared to the existing treatment methodologies used.Featured Application:In this study,we have measured the concentrations of contaminants in acid mine drainage(AMD)and municipal wastewater(MWW)and conducted the combined treatment in phases I and II.This is significant because in previous years there was a massive fish kill that is linked to the high total dissolved solids(TDS)and salinity content in the water.With the current proposed combined treatment technology,it shows high potential in reducing TDS and salinity content in the combined wastewater which will prevent similar accident(Dunkard creek fish kill in 2019)happening again.

Control of fermentation types in continuous-flow acidogenic reactors:effects of pH and redox potential

The experiments were carried out in continuous flow acidogenic reactors with molasses used as substrate to study the effects of pH and redox potential on fermentation types. The conditions for each fermentation type were investigated at different experimental stages of start up, pH regulating and redox potential regulating. The experiments confirmed that butyric acid type fermentation would occur at pH > 6, the propionic acid type fermentation at pH about 5.5 with E h> -278 mV, and the ethanol type fermentation at pH < 4.5. A higher redox potential will lead to propionic acid type fermentation because propionogens are facultative anaerobic bacteria.

Development and application of some renovated technologies for municipal wastewater treatment in China

China has been experiencing fast economic development in recent decades at the cost of serious environ-mental deterioration.Wastewater discharge,especially municipal wastewater discharge,and non-point pollution sources are becoming the major water pollution source and research focus.Great efforts have been made on water pollu-tion control and a number of renovated technologies and pro-cesses for municipal wastewater treatment and reclamation as well as non-point pollution control have been developed and applied in China.This paper discusses the development and application of the appropriate technologies,including natural treatment systems,anaerobic biological treatment,biofilm reactors and wastewater reclamation technologies,for water pollution control in the country.

Anaerobic treatment of wastewater containing methanol in up-flow anaerobic sludge bed (UASB) reactor

The direct conversion of methanol into methane is the main process in anaerobic treatment of methanol containing wastewater.However,acetic acid can also be produced from methanol theoretically,which may probably result in an abrupt pH drop and deteriorate the anaerobic process.Therefore,it is interesting to know what would really happen in an anaerobic reactor treating methanol wastewater.In this study,an up-flow anaerobic sludge bed(UASB)reactor treating methanol wastewater was operated.The chemical oxygen demand(COD),acetic acid and pH of the effluent were monitored at different loadings and influent alkalinity.The results showed that the anaerobic reactor could be operated steadily at as low as 119 mg/L of influent alkalinity and high organic loading rate with no obvious pH drops.Volatile fatty acids accumulation was not observed even at strong shock loadings.The microorganisms in the sludge at the end of the test became homogeneous in morphology,which were mainly spherical or spheroidal in shape.

Anaerobic treatment of source-separated domestic bio-wastes with an improved upflow solid reactor at a short HRT

Anaerobic treatment is the core technology for resource and energy recovery from source-separated domestic bio-wastes. The higher efficiency of an improved upflow solid reactor（IUSR） designed in this study was demonstrated in the treatment of concentrated black water and kitchen waste. The highest methane production of 48 L/person/day was achieved at the hydraulic retention time（HRT） of 7 days, while the other measures of performance at the HRT of 8.3 days were better than at the HRT of 7 or 10 days, achieving a methane production of 43 L/person/day, removal of total chemical oxygen demand（TCOD）of 89%, removal of soluble chemical oxygen demand（SCOD） of 92%, and conversion of chemical oxygen demand（COD） to methane of 71%. It is not recommended to decrease HRT lower than 7 days due to the instability of the initial period. The concentrations of volatile fatty acids（VFAs） in the IUSR were less than 10 mg/L, indicating that the anaerobic process was stable. Sludge bed development showed that sludge bed with high microbial activity was formed in the bottom and that the precipitation zone of effluents formed should preferably occupy 30% of the height of the IUSR. The effluents of the IUSR could be used for irrigation in agriculture in combination with a settling tank accompanied by disinfection to remove solids and pathogens.

A syntrophic propionate-oxidizing microflora and its bioaugmentation on anaerobic wastewater treatment for enhancing methane production and COD removal

Methane fermentation process can be restricted and even destroyed by the accumulation of propionate because it is the most difficult to be anaerobically oxidized among the volatile fatty acids produced by acetogenesis. To enhance anaerobic wastewater treatment process for methane production and COD removal, a syntrophic propionate-oxidizing microflora B83 was obtained from an anaerobic activated sludge by enrichment with propionate. The inoculation of microflora B83, with a 1：9 ratio of bacteria number to that of the activated sludge, could enhance the methane production from glucose by 2.5 times. With the same inoculation dosage of the microflora B83, COD removal in organic wastewater treatment process was improved from 75.6% to 86.6%, while the specific methane production by COD removal was increased by 2.7 times. Hydrogen-producing acetogene_sis.appeared to be a rate-limiting step in methane termentation, and the enhancement orhydrogen-producing acetogens in the anaerobic wastewater treatment process had improved not only the hydrogen-producing acetogenesis but also the acidogenesis and methanogenesis.

Challenges of a feasible route towards sustainability in environmental protection

Anaerobic processes for treatment of low and high strength wastewaters and solid wastes constitute the core method in the natural biological mineralization(NBM)treatment concept.When adequately combined with the complementary NBM-systems and modern clean water saving practices in wastewater collection and transport,they represent a feasible route to sustainable environmental protection(EPsus),in essence even towards a more sustainable society.Despite the development and implementation of modern high rate Anaerobic Wastewater Treatment(AnWT-)systems and complementary innovative NBM-processes,the considerable progress made since the seventies in fundamental insights in microbiology,biochemistry and process technology,still numerous challenging improvements in the NBM-field can be realized.This contribution is mainly based on the insights attained from wide ranging literature evaluations and the results of experimental research conducted by numerous PhD students who participated in our group over the last four decades.An attempt is made here to identify major facets on which an improved insight can,and consequently should,be obtained in order to accomplish more optimal operation and design of various types of Anaerobic Degradation(AnDeg-)processes.

Technical measures to achieve a cleaner production mode for recycled paper mills

China’s paper production reached 79.8×10^(6) t in 2008 and ranked number one in the world.Because of its high consumption of water,energy and materials and its serious pollution,the present processes are not likely to be sustainable.An alternative,the closed Water Loop-Papermaking Integration(WLPI)method,is put forward in this paper.The WLPI method can be realized in a recycled paper mill by adding technologies and using recycled water.Many industrial case studies have shown that a large quantity of water,energy and materials can be saved,and the quantity of waste sludge and wastewater discharge was minimized by using the WLPI method.The design of the water reuse system,control of calcium hardness,water recycling and minimal waste sludge are discussed.Anaerobic technology plays an important role in the WLPI method to lower cost,energy use and waste.In the brown paper and coated white board production,zeroeffluent discharge can be realized.Fresh water consumption is only 1-2m^(3)·t^(-1).For the paper mills with deinking and bleaching processes,about 10 m^(3)·t^(-1) of fresh water and a similar amount of effluent discharge are needed.Power saving using anaerobic technology is 70%when recycled water is used in comparison with the conventional activated sludge process.Waste sludge can be decreased to about 5%of the initial process due to reuse of the waste sludge and the lower bio-sludge production of the anaerobic process.

Removal of anaerobic soluble microbial products in a biological activated carbon reactor

The soluble microbial products （SMP） in the biological treatment effluent are generally of great amount and are poorly biodegradable. Focusing on the biodegradation of anaerobic SMP, the biological activated carbon （BAC） was introduced into the anaerobic system. The experiments were conducted in two identical lab-scale up-flow anaerobic sludge blanket （UASB） reactors. The high strength organics were degraded in the first UASB reactor （UASB1） and the second UASB （UASB2, i.e., BAC） functioned as a polishing step to remove SMP produced in UASB1. The results showed that 90% of the SMP could be removed before granular activated carbon was saturated. After the saturation, the SMP removal decreased to 60% on the average. Analysis of granular activated carbon adsorption revealed that the main role of SMP removal in BAC reactor was biodegradation. A strain of SMP-degrading bacteria, which was found highly similar to Klebsiella sp., was isolated, enriched and inoculated back to the BAC reactor. When the influent chemical oxygen demand （COD） was 10,000 mg/L and the organic loading rate achieved 10 kg COD/（m 3 ·day）, the effluent from the BAC reactor could meet the discharge standard without further treatment. Anaerobic BAC reactor inoculated with the isolated Klebsiella was proved to be an effective, cheap and easy technical treatment approach for the removal of SMP in the treatment of easily-degradable wastewater with COD lower than 10,000 mg/L.

Elucidating the removal mechanism of N,N-dimethyldithiocarbamate in an anaerobic-anoxic-oxic activated sludge system

N,N-Dimethyldithiocarbamate （DMDTC） is a typical precursor of N-nitrosodimethylamine （NDMA）. Based on separate hydrolysis, sorption and biodegradation studies of DMDTC, a laboratory-scale anaerobic-anoxic-oxic （AAO） system was established to investigate the removal mechanism of DMDTC in this nutrient removal biological treatment system. DMDTC hydrolyzed easily in water solution under either acidic conditions or strong alkaline conditions, and dimethylamine （DMA） was the main hydrolysate. Under anaerobic, anoxic or oxic conditions, DMDTC was biodegraded and completely mineralized. Furthermore, DMA was the main intermediate in DMDTC biodegradation. In the AAO system, the optimal conditions for both nutrient and DMDTC removal were hydraulic retention time 8 hr, sludge retention time 20 day, mixed-liquor return ratio 3：1 and sludge return ratio 1：1. Under these conditions, the removal efficiency of DMDTC reached 99.5%; the removal efficiencies of chemical organic demand, ammonium nitrogen, total nitrogen and total phosphorus were 90%, 98%, 81% and 93%, respectively. Biodegradation is the dominant mechanism for DMDTC removal in the AAO system, which was elucidated as consisting of two steps： first, DMDTC is transformed to DMA in the anaerobic and anoxic units, and then DMA is mineralized to CO2 and NH3 in the anoxic and oxic units. The mineralization of DMDTC in the biological treatment system can effectively avoid the formation of NDMA during subsequent disinfection processes.

Impact of undissociated volatile fatty acids on acidogenesis in a two-phase anaerobic system

This study investigated the degradation and production of volatile fatty acids（VFAs）in the acidogenic phase reactor of a two-phase anaerobic system.20 mmol/L bromoethanesulfonic acid（BESA）was used to inhibit acidogenic methanogens（which were present in the acidogenic phase reactor）from degrading VFAs.The impact of undissociated volatile fatty acids（un VFAs）on＂net＂VFAs production in the acidogenic phase reactor was then evaluated,with the exclusion of concurrent VFAs degradation.＂Net＂VFAs production from glucose degradation was partially inhibited at high un VFAs concentrations,with 59%,37% and 60% reduction in production rates at 2190 mg chemical oxygen demand（COD）/L undissociated acetic acid（un HAc）,2130 mg COD/L undissociated propionic acid（un HPr）and 2280 mg COD/L undissociated n-butyric acid（un HBu）,respectively.The profile of VFAs produced further indicated that while an un VFA can primarily affect its own formation,there were also un VFAs that affected the formation of other VFAs.

Dissolved methane in anaerobic effluent:Emission or recovery?

Various anaerobic processes have been explored for the energy-efficient treatment of municipal wastewater.However,dissolved methane in anaerobic effluent appears to be a barrier towards the energy and carbon neutrality of wastewater treatment.Although several dissolved methane recovery methods have been developed,their engineering feasibility and economic viability have not yet been assessed in a holistic manner.In this perspective,we thus intend to offer additional insights into the cost-benefit of dissolved methane recovery against its emission.

Enhanced anaerobic fermentation with azo dye as electron acceptor: Simultaneous acceleration of organics decomposition and azo decolorization

Accumulation of hydrogen during anaerobic processes usually results in low decomposition of volatile organic acids（VFAs）. On the other hand, hydrogen is a good electron donor for dye reduction, which would help the acetogenic conversion in keeping low hydrogen concentration. The main objective of the study was to accelerate VFA composition through using azo dye as electron acceptor. The results indicated that the azo dye serving as an electron acceptor could avoid H2 accumulation and accelerate anaerobic digestion of VFAs. After adding the azo dye, propionate decreased from 2400.0 to 689.5 mg/L and acetate production increased from 180.0 to 519.5 mg/L. It meant that the conversion of propionate into acetate was enhanced. Fluorescence in situ hybridization analysis showed that the abundance of propionate-utilizing acetogens with the presence of azo dye was greater than that in a reference without azo dye. The experiments via using glucose as the substrate further demonstrated that the VFA decomposition and the chemical oxygen demand（COD） removal increased by 319.7 mg/L and 23.3% respectively after adding the azo dye. Therefore, adding moderate azo dye might be a way to recover anaerobic system from deterioration due to the accumulation of H2 or VFAs.