厌氧消化技术在日本有机废水和废弃物处理中的应用

日本污泥厌氧消化始于1932年,目前污泥厌氧消化工程已超过300个,消化池总容积达210×10<'4>m<'3>.目前,全日本共有300多座升流式厌氧污泥床反应器(upflow anaerobic sludgebed,UASB)和膨胀颗粒污泥床(expanded granular sludge bed,EGSB)处理厂,主要用于包括啤酒废水、软饮料废水、酿酒废水、食品加工废水和化工废水在内的高浓度有机工业废水的处理.总结了厌氧消化技术在日本有机废水和有机废弃物处理中的应用状况,以及运行参数.此外,对日本厌氧消化技术在厌氧膜生物反应器、产氢产甲烷两段发酵和沼气生物脱硫等方面的新进展也进行了介绍.     

制药废水处理工艺的改造

某制药厂由于新上生产项目,使综合废水中有机污染物和硫酸盐浓度大幅升高,所以必须对原处理工艺进行改造.改造工艺主要采用UASB反应器、SBR反应器及深层曝气池,其中UASB反应器采用两相(产酸及硫酸盐还原相、产甲烷相)厌氧技术以减少硫酸盐对厌氧过程的影响.经改造后,出水水质达到<污水综合排放标准>(GB 8978-1996)的一级标准.     

高温／中温两相厌氧消化处理污水污泥和有机废物

本文研究了高温／中温两相厌氧消化反应器系统用于同时处理城市污水厂污涨和其它高浓度有机废物，目的在于考察该系统分别同时处理污水厂污泥与马铃薯加工废物，污泥与猪血及污泥与罐肠加工废物时的效能变化，为拟建实际规模高温／中温两相厌氧消化系统提供技术依据。     

微量元素对ABR发酵产氢产甲烷的影响

为构建厌氧折流板反应器(ABR)发酵联合产氢产甲烷系统,考察了微量元素对ABR系统前端格室发酵产氢、后端格室发酵产甲烷的影响。在进水COD为6 000 mg/L、碱度为1 900 mg/L的条件下,当未投加微量元素时,系统对COD的去除率为51%,产氢能力为0.46 m3/(m3.d),产甲烷能力为0.68 m3/(m3.d),四格室的厌氧污泥脱氢酶活性均较低;而在相同运行条件下,当投加微量元素后,系统对COD的去除率提高到62%以上,产氢能力为0.37 m3/(m3.d),产甲烷能力达到1.66 m3/(m3.d)。研究表明,投加微量元素可有效刺激ABR发酵联合产氢产甲烷系统中厌氧污泥的活性,由于ABR中产甲烷菌等耗氢菌群活性的增强导致发酵产氢作用受到抑制,但产甲烷活性的进一步增强,使系统的处理效能得到明显提高。     

两相厌氧/膜生物反应器工艺的快速启动

为了实现两相厌氧/膜生物反应器(TPAD/MBR)工艺处理制药废水的快速启动,采用混合污泥接种,对产酸相、产甲烷相和MBR进行分步启动。结果表明:产酸相的启动时间为42d,对COD的平均去除率为41.7%;产甲烷相的启动时间为20 d,对COD的平均去除率为86.7%;MBR的启动时间为12 d,对COD的平均去除率为95.2%,出水COD80 mg/L。废水经产酸相处理后挥发酸平均含量为2 569 mg/L,其中乙酸和乙醇的平均含量分别为873 mg/L和1 127 mg/L,这证明经过产酸相后废水的可生化性大大提高,为产甲烷相的进一步处理提供了有利条件。产酸相的最佳pH值为4.8~5.2,产甲烷相的最佳pH值为6.5~7.0。接种混合污泥及分步启动缩短了产酸相、产甲烷相和MBR的启动时间,实现了TPAD/MBR工艺的快速启动。     

改进型酸化反应器处理含硫酸盐酸性有机废水

为避免在两相厌氧处理工艺中设置pH调节单元,在中温（35℃）条件下,采用改进型酸化反应器处理含硫酸盐酸性有机废水,考察了其处理效果。结果表明,在进水pH值为5.5、COD/SO4^2-值为4.8的条件下,出水pH值为6.9～7.2、COD/SO4^2-值为9.2～12.5,水质可满足后续产甲烷反应器对进水的要求。     

两相厌氧系统处理磺胺废水的试验研究

高浓度有机酸性磺胺废水通过中和、稀释、两相厌氧处理及对所产甲烷的毒性检测结果表明，该废水对产酸菌和产甲烷菌都有毒害抑制作用，但经中和、用其他废水稀释7倍后可进行厌氧处理，同时提出了适宜处理磺胺废水的工艺流程。     

有机固废厌氧产沼气产业发展现状及政策需求

我国有机固体废弃物具有产量大、资源化率低、处理政策不完善等特点,将有机固体废弃物(城镇污泥、厨余垃圾及人畜粪便、有机固体废弃物垃圾)经厌氧产沼气处理对解决我国的此类污染和实现有机固废资源化意义显著。首先分析了我国有机固废厌氧产沼气产业的发展现状,在此基础上,为了全面促进有机固废产沼气的发展,提出了促进相关产业发展的政策需求。相关研究成果有望为我国固废产沼气的产业健康发展提供技术支持。     

厌氧同时反硝化产甲烷工艺的应用及进展

厌氧同时反硝化产甲烷工艺能够充分利用废水中的有机碳源,在实现生物脱氮的同时产生甲烷,其关键是如何减小或消除硝态氮（NO^- -N）对产甲烷茵的抑制作用。目前,解决该问题的主要手段有培养同时反硝化产甲烷颗粒污泥和生物膜等方法。研究表明,厌氧同时反硝化产甲烷反应器串联好氧硝化反应器（SDMR—ANR）系统,适于处理早期的垃圾渗滤液、屠宰废水等含高浓度有机物和高NH4＋ -N的废水,其中进水COD／N03- -N和好氧反应器出水回流比是影响其运行效果的关键因素。此外,还介绍了厌氧同时反硝化产甲烷工艺的微生物种群结构及进一步的功能扩展。     

二相厌氧处理有机废水过程特性及生物相研究

依据二相厌氧机理设计实验反应器,采用人工配制水样作为实验用水,利用色谱-质谱联动仪分析二相厌氧各阶段水质的特性。实验结果表明:经二相厌氧反应后,有机物的种类没有减少,相反增加了许多水解、酸化反应的小分子中间产物,产酸反应器将大分子难降解化合物降解为易降解酸性小分子化合物,可生化性有所提高,再经过产甲烷反应器最终处理后,出水的化合物种类和含量有明显减少。     

Effect of anaerobic reactor process configuration on useful energy production

The effect of reactor process configuration on anaerobic production of useful energy (hydrogen and methane) from a complex substrate was investigated for the following reactor systems: suspended growth, two-phase mixed, two-stage mixed, upflow anaerobic sludge blanket (UASB) reactor, and two-phase UASB. The mixed two-phase and two-stage configurations yielded the highest specific energy productions of 13.3 and 13.4 kJ/g COD fed, respectively. Reactor process configuration influenced microbial pathways in acidogenic reactors in that butyrate was the predominant volatile acid in phased configurations, whereas acetate was predominant in the staged configuration. The UASB reactor achieved the highest average daily energy production per reactor volume of 101 kJ/L reactor-d. All reactor configurations achieved high COD removals on the order of 99%. However, hydrogen represented only 3% of the total energy produced by the two-phase mixed and two-phase UASB configurations. Theoretical analysis revealed that the maximum specific energy production by the two-phase suspended-growth configuration is only 9% higher than that for a single-stage mixed reactor. Consequently, the production of hydrogen from complex substrates in these process configurations does not seem to be justifiable solely from an energy point of view. Instead, it is suggested that phased anaerobic systems should be considered primarily for improved process stability whereas resultant hydrogen production is of secondary benefit.     

Mitigating ammonia inhibition of thermophilic anaerobic treatment of digested piggery wastewater: use of pH reduction, zeolite, biomass and humic acid

High free ammonia released during anaerobic digestion of livestock wastes is widely known to inhibit methanogenic microorganisms and result in low methane production. This was encountered during our earlier thermophilic semi-continuously fed continuously-stirred tank reactor (CSTR) treatment of piggery wastewater. This study explored chemical and biological means to mitigate ammonia inhibition on thermophilic anaerobic treatment of piggery wastewater with the aim to increase organic volatile carbon reduction and methane production. A series of thermophilic anaerobic batch experiments were conducted on the digested piggery effluent to investigate the effects of pH reduction (pH 8.3 to 7.5, 7.0 and 6.5) and additions of biomass (10% v/v and 19% v/v anaerobic digested piggery biomass and aerobic-anaerobic digested municipal biomass), natural zeolite (10, 15 and 20 g/L) and humic acid (1, 5 and 10 g/L) on methane production at 55 °C for 9-11 days. Reduction of the wastewater pH from its initial pH of 8.3 to 6.5 produced the greatest stimulation of methane production (3.4 fold) coupled with reductions in free ammonia (38 fold) and total volatile fatty acids (58% TVFA), particularly acetate and propionate. Addition of 10-20 g/L zeolite to piggery wastewater with and without pH reduction to 6.5 further enhanced total VFA reduction and methane production over their respective controls, with 20 g/L zeolite producing the highest enhancement effect despite the ammonia-nitrogen concentrations of the treated wastewaters remaining high. Without pH reduction, zeolite concentration up to 20 g/L was required to achieve comparable methane enhancement as the pH-reduced wastewater at pH 6.5. Although biomass (10% v/v piggery and municipal wastes) and low humic acid (1 and 5 g/L) additions enhanced total VFA reduction and methane production, they elevated the residual effluent total COD concentrations over the control wastewaters (pH-unadjusted and pH-reduced) unlike zeolite treatment. The outcomes from these batch experiments support the use of pH reduction to 6.5 and zeolite treatment (10-20 g/L) as effective strategies to mitigate ammonia inhibition of the thermophilic anaerobic treatment of piggery wastewater.     

Dynamic modelling of anaerobic digestion

The anaerobic digestion model presented here considers a two step process. First, acidogenic bacteria convert glucose into acetate then methanogenic bacteria convert this acid into methane and carbon dioxide. The biomass and metabolite production rates are described by distinct relations. Therefore, there is not a direct relationship between the growth and the energy production related to metabolite formation. The inhibitory effects of the unionized acid concentration on growth rate of both bacterial populations and the methane production from acetate were considered separately. The model was tested in batch cultures with two types of organic loads, i.e. pea bleaching wastewaters and a synthetic substrate containing sucrose and organic acid. The model allowed to simulate satisfactorily the methane production under very different operational conditions.     

Integrated application of upflow anaerobic sludge blanket reactor for the treatment of wastewaters

The UASB process among other treatment methods has been recognized as a core method of an advanced technology for environmental protection. This paper highlights the treatment of seven types of wastewaters i.e. palm oil mill effluent (POME), distillery wastewater, slaughterhouse wastewater, piggery wastewater, dairy wastewater, fishery wastewater and municipal wastewater (black and gray) by UASB process. The purpose of this study is to explore the pollution load of these wastewaters and their treatment potential use in upflow anaerobic sludge blanket process. The general characterization of wastewater, treatment in UASB reactor with operational parameters and reactor performance in terms of COD removal and biogas production are thoroughly discussed in the paper. The concrete data illustrates the reactor configuration, thus giving maximum awareness about upflow anaerobic sludge blanket reactor for further research. The future aspects for research needs are also outlined.     

Developments of bacterial population and methanogenic activity in a laboratory-scale landfill bioreactor

Sludge was taken from laboratory-scale simulators of a landfill bioreactor (LFBR) treating the organic fraction of municipal solid wastes (OFMSW) over a period of 1 year. Population densities of acetogens, hydrogen- and acetate-utilizing methanogens and the specific methanogenic activity (SMA) on degrading butyrate, propionate, acetate and formate were measured. The results indicate that the Gompertz equation is a suitable model for describing the growth data of acetogens, hydrogen- and acetate-utilizing methanogens. The development of SMAs can be systematically described by a simple mathematical equation derived from the Gompertz equation. The measurements of bacterial population growth and methanogenic activity reveal that the SMA of acetate is an ultimate indicator for monitoring the OFMSW decomposition. Leachate recycling can stimulate the carbon flow from hydrolysis/fermentation through the hydrogen/acetate toward methane. A moisture content of 75% is suggested to be an initial rapid decomposition threshold for the anaerobic organic refuse mineralization in a landfill bioreactor.     

Novel method for enhancing permeate flux of submerged membrane system in two-phase anaerobic reactor

A two-phase anaerobic reactor system with a submerged membrane in the acidogenic reactor was designed for the enhancement of organic acid conversion and methane recovery. A submerged membrane system in a two-phase anaerobic reactor was tested to increase the sludge retention time (SRT) of acidogen and to enhance the solid separation. The pilot plant experiment was performed for piggery wastewater treatment for a year. The membrane material used was mixed esters of cellulose of 0.5 micron pore size. COD removal efficiency was 80% and the methane production showed 0.32 m3/kg COD removed for the submerged membrane system in the anaerobic digester. As the cake resistance of the membrane caused a serious problem, a stainless-steel prefilter and air backwashing methods were applied to minimize the cake resistance effectively. Among the tested prefilters, the 63 microns pore prefilter showed the best performance for reducing cake resistance and a successful long-term operation. By cleaning with alkali first and acidic solutions later, the permeate flux decreased by long-term operation was recovered to 89% of that with a new membrane.     

The effects of organic toxicants on methane production and hydrogen gas levels during the anaerobic digestion of waste activated sludge

Batch serum bottle assays were conducted to examine the response of the anaerobic digestion process to inhibition induced by the pulse addition of four organic toxicants [chloroform, bromoethanesulfonic acid (BES), trichloroacetic acid (TCAA) and formaldehyde]. The impact that increasing levels of inhibition of methane production had on hydrogen response and volatile fatty acid (VFA) accumulation were examined. All of the toxicants, with the exception of formaldehyde, appeared to elicit similar hydrogen response patterns and VFA accumulations for similar levels of inhibition. Results indicate that both the hydrogen and acetate catabolizing methanogenic populations were inhibited to approximately the same extent by chloroform, BES, and TCAA. Severe inhibition of methane production (>70% reduction of methane produced compared to controls) resulted in a rapid accumulation of hydrogen in the gaseous headspace. When inhibition was less severe, hydrogen accumulated to levels only slightly above controls. Based on these preliminary results, there appears to be some limits on the potential of using hydrogen as an early warning indicator of process upset. Results do indicate, however, that monitoring hydrogen in consert with conventional process indicators should improve digester monitoring and may provide more rapid indication of process upsets due to toxic shocks.     

污泥两相厌氧消化反应器生物相研究

采用中温两相厌氧消化处理污泥,通过对颗粒污泥形成过程中的污泥含水率、VS/TS、产气率、所产气体的甲烷含量及污泥元素等分析和对颗粒污泥中优势产甲烷菌的扫描（SEM）电镜观察,阐明了颗粒污泥的形成过程及特性。     

Effect of polyelectrolytes and quaternary ammonium compounds on the anaerobic biological treatment of poultry processing wastewater

Quaternary ammonium compounds (QACs) and polyelectrolytes are extensively used in poultry processing facilities as sanitizing agents and flocculants, respectively. These chemicals may affect the performance of biological treatment systems resulting in low effluent quality. The impact of these chemicals on the anaerobic treatment of poultry processing wastewater (PPWW) samples, collected before and after a solids separation process, was tested in batch assays using a mixed, mesophilic (35 degrees C) methanogenic culture. The results of this study showed that Vigilquat (VQ), a commercial mixture of four QACs, has a high affinity for the organic solids in the PPWW. Cationic and anionic polyelectrolytes, alone or in combination, did not have any adverse effect on the anaerobic biodegradation of PPWW at concentrations typically used in poultry processing facilities (20 and 5 mg/L, respectively). In spite of the high affinity of VQ for the PPWW solids, VQ at a concentration of 50mg/L and above adversely affected the anaerobic degradation of the PPWW, which resulted in a significantly reduced methane production and accumulation of volatile fatty acids. In the absence of any inhibition, the methane yield varied from 0.76 to 0.98 L methane at STP per g volatile solids added. VQ was not biodegraded under the batch, methanogenic conditions used in this study.