初沉污泥厌氧消化中试系统的启动与调试

为了更好地实现污泥减量化和资源化,将污水气浮处理系统与初沉污泥中温厌氧消化系统相结合,用污水气浮处理系统产生的初沉污泥进行厌氧消化,并且进行中试系统的启动和调试。结果表明:在初沉污泥中温厌氧消化系统启动过程中,TS和VS去除率,日产沼气量,沼气产率和甲烷含量都呈现出先逐渐升高,再逐渐降低,并最终趋于稳定的趋势。p H为7.3~7.8,TS和VS的平均去除率分别是24%和30%,日产沼气量和沼气产率分别是188 L/d和224 L/kg,甲烷含量基本稳定在56%左右,中试系统成功地启动并运行。     

添加剂及抑制剂对餐厨垃圾厌氧消化性能的影响

厌氧消化处理餐厨垃圾已成为餐厨垃圾处理的发展趋势,为探索加入添加剂对其厌氧消化性能的影响,设置了4个试验组:以不加添加剂的餐厨垃圾为对照,研究了添加膨润土、铁盐及活性炭对餐厨垃圾厌氧消化产气量、甲烷含量以及BOD5去除率的影响。结果表明:加入添加剂能显著提高餐厨垃圾的产气量及VS产气率,还可显著提高餐厨垃圾BOD5的去除率。3种添加剂效果的大小顺序为添加膨润土添加铁盐添加活性炭。同时还探索了3种抑制剂对厌氧消化性能的影响,加入抑制剂可显著降低餐厨垃圾的产气量,氨氮的抑制效果最显著,其次为硫化氢,再次为Na+,产气量分别比对照减少了47.8%、 42.6%和32.4%。添加剂和抑制剂对沼气中甲烷含量(体积分数)的影响均不大,与对照相比没有明显差异。     

一种餐厨垃圾浆液的CSTR厌氧反应器处理试验研究

利用中温CSTR厌氧反应器处理餐厨垃圾经机械预处理后的有机浆液,进液COD均值为150 960mg/L,COD去除率达84.1%,厌氧进、出液的pH均值分别是4.5和7.7,厌氧进、出液的TS均值分别为7.5%和2.4%,厌氧反应器的出液VFA为2 000~3 000 mg/L,NH_3-N浓度和碱度(CaCO_3)分别保持在3 700 mg/L和19 000 mg/L左右,厌氧系统运行稳定。研究还表明:每吨餐厨垃圾有机浆液的沼气产量大于60 m~3,沼气中甲烷的含量保持在60%左右,餐厨垃圾有机浆液COD的产气率为0.49 m3/kg。     

餐厨垃圾发酵产气潜力与特性

以餐厨垃圾为发酵原料,在恒温37℃下进行批式沼气发酵试验,测定发酵过程中的VS产气潜力、产气速率、p H等指标。结果显示:在4.0 kg/m3负荷下运行沼气中CH4含量为73.40%,甲烷产率为377 m L/g,甲烷含量、VS利用率与甲烷产率方面都明显优于在2.0 kg/m3负荷下运行结果。     

餐厨垃圾厌氧消化影响因素分析

阐述了近年来餐厨垃圾厌氧消化的研究进展,分别讨论了含固率、有机负荷、Na~+、VFAs与氨氮、消化温度和含油量在餐厨垃圾厌氧消化过程中的影响,并总结了适量掺加污泥对餐厨垃圾厌氧消化的促进作用:一是污泥可以稀释餐厨浆液中的Na~+浓度;二是保持厌氧消化系统的弱碱性,进而提升餐厨厌氧消化性能。     

城市餐厨垃圾的厌氧消化处理研究

研究了不同处理量下,系统反应温度对餐厨垃圾厌氧消化过程中产气量的影响,分析了餐厨垃圾厌氧消化处理过程中,产气量与进料TS浓度的关系以及气体成分的差异。结果表明：在相同处理量下,与中温35℃的反应温度相比,高温55℃下系统产气速率较快,产气高峰较早到达;系统日产气量与进料TS的变化基本一致,平均产气能力达到0.45 m3/kg,气体成分中甲烷含量均高于55%。     

泔水垃圾单相湿法厌氧发酵技术研究

采用中温单相湿法厌氧消化工艺对泔水垃圾进行处理,考察了对COD、TS的去除效果和产气中的甲烷含量,探讨了发酵过程中碱度、氨氮、pH和脂肪酸的变化规律。结果表明:在反应器温度为(35±1)℃和接种物50%的条件下,该工艺对COD的去除率为43%,对TS的去除率为85%,发酵期内发酵气体产生量达到110mL/g。     

餐厨垃圾半干式高温厌氧发酵快速启动试验

采用消化污泥为接种物,在高温(54～57℃)条件下,应用连续半干式厌氧消化技术对餐厨垃圾进行了实验室规模的快速启动试验.在启动阶段,进料负荷根据反应器产气速率及pH的变化呈阶梯状提高.试验结果表明:反应器启动29d以后,系统pH稳定在6.9～7.6,平均产气速率18.0 L/d,反应器启动55 d以后,平均产气速率为18.9L/d,平均产气效率973.2 mL/g(以VS计),反应器有机负荷率达到3.Og/(L·d).     

餐厨垃圾特性分析及处理方式探讨——以广西师范学院食堂餐厨垃圾为例

以广西师范学院食堂餐厨垃圾为研究对象,分析测试其春、夏、秋、冬4季的p H、密度、TS、VS、固定碳、灰分等理化指标,得出其主要特性:1p H为5~6.5,呈偏酸性,密度约1 kg/L,含水率高,TS为8%~20%,VS较高、约85%,固定碳约4%,灰分为5.5%~16.5%;2早餐后餐厨垃圾的p H、密度、TS是一日三餐中最低的,而其灰分是一日三餐中最高的;3春、夏2季餐厨垃圾固定碳含量明显高于秋、冬2季。预处理+两相(产酸相+产甲烷相)厌氧消化是适于处理这种特性餐厨垃圾的工艺。     

不同接种物对厨余垃圾厌氧发酵的影响

以分类收集到的厨余垃圾为发酵底物,以湿式厌氧污泥及养牛场牛粪为接种物,在中温(38±1)℃,接种比为接种物∶厨余垃圾=2∶1的试验条件下,对比研究了不同接种物对厨余垃圾厌氧发酵的影响。结果表明:餐厨垃圾湿式厌氧污泥相对于养牛场牛粪有更好的接种效果;湿式厌氧污泥中的消化污泥接种效果最好,发酵启动第3天即可达到日产气量峰值,累积产气量最高,为1 619 mL,VS降解率为21.7%。     

固含量对生物废物干式厌氧消化的影响

采用干式厌氧消化技术研究生物废物在不同固含量(20%、30%、40%)条件下的pH、氧化还原电位、纤维素酶和果胶酶活力变化情况,比较了不同条件下VS与CODCr的去除率及产气情况.结果表明:高固含量引起的酸化现象使系统的正常运行受到影响,氧化还原电位开始持续下降趋势,后期有所回升;固含量20%的罐体纤维素酶活力相对较高,3个罐体的果胶酶活力在消化过程中出现了4个大小不同的峰值;固含量20%的罐体VS与CODCr降解效果较好,去除率分别为38.16%、63.95%,其罐体产气总量和甲烷含量分别为2 424.5 mL、45.2%,在3个罐体中最高.     

有机负荷对餐厨单相厌氧消化产甲烷的影响

采用消化污泥接种,在中温条件下（37℃左右）以连续式单项厌氧消化技术对餐厨单独厌氧消化进行研究.实验中以产气量、产气中甲烷含量、消化液中氨氮及总氮浓度、体系中pH以及有机质降解率为指标,研究高含固率条件下（含固率12％）有机负荷对餐厨垃圾厌氧消化产甲烷的影响.结果表明：当有机负荷为2.5～3.0 kg/（m^3·d）时,厌氧消化总体效果较好,体系中各项指标均维持在较好水平.继续提高有机负荷,体系中pH下降,氨氮浓度上升,产气率及有机质降解率明显下降,不利于厌氧消化的进行.     

生活污泥高温-中温两相厌氧消化中试装置的设计

以典型10万t/d的生活污水厂产生的污泥量缩小1万倍为设计基准,建立高温-中温两相厌氧消化中试装置.通过对消化池、进泥排泥系统、搅拌系统、热交换系统和集气系统、在线监控系统等各子系统的比较和选型,选出适合中试试验的装置模型.结合运行实际,分析中试装置的不足,并提出改进措施.     

Fate of selected chlorinated organic compounds during semi-continuous anaerobic sludge digestion

The predominant sewage sludge treatment process in the United Kingdom is mesophilic anaerobic digestion. The fate of chlorinated organic micropollutants during this treatment process is, however, largely unknown. Laboratory scale simulations were applied to assess the fate of chlorophenoxy herbicides, chlorophenols, polychlorinated biphenyls, and organochlorine pesticides during the digestion of primary sludge and co-settled waste activated and primary sludge, obtained from full scale works. Incubation was carried out under non-sterile and sterile conditions. The results are compared with previous batch tests and the potential mechanisms of removal are discussed.     

生活垃圾厌氧发酵制沼气研究

以天津市的居民生活垃圾、食堂垃圾、市场垃圾为实验原料,采用高温和中温发酵,研究了发酵过程中的累计产气量、pH、甲烷和二氧化碳浓度变化情况.初步总结和分析这些变化规律,并对垃圾厌氧发酵制沼气技术给予建议.     

Upflow anaerobic sludge blanket reactor--a review

Biological treatment of wastewater basically reduces the pollutant concentration through microbial coagulation and removal of non-settleable organic colloidal solids. Organic matter is biologically stabilized so that no further oxygen demand is exerted by it. The biological treatment requires contact of the biomass with the substrate. Various advances and improvements in anaerobic reactors to achieve variations in contact time and method of contact have resulted in development of in suspended growth systems, attached growth or fixed film systems or combinations thereof. Although anaerobic systems for waste treatment have been used since late 19th century, they were considered to have limited treatment efficiencies and were too slow to serve the needs of a quickly expanding wastewater volume, especially in industrialized and densely populated areas. At present aerobic treatment is the most commonly used process to reduce the organic pollution level of both domestic and industrial wastewaters. Aerobic techniques, such as activated sludge process, trickling filters, oxidation ponds and aerated lagoons, with more or less intense mixing devices, have been successfully installed for domestic wastewater as well as industrial wastewater treatment. Anaerobic digestion systems have undergone modifications in the last two decades, mainly as a result of the energy crisis. Major developments have been made with regard to anaerobic metabolism, physiological interactions among different microbial species, effects of toxic compounds and biomass accumulation. Recent developments however, have demonstrated that anaerobic processes might be an economically attractive alternative for the treatment of different types of industrial wastewaters and in (semi-) tropical areas also for domestic wastewaters. The anaerobic degradation of complex, particulate organic matter has been described as a multistep process of series and parallel reactions. It involves the decomposition of organic and inorganic matter in the absence of molecular oxygen. Complex polymeric materials such as polysaccharides, proteins, and lipids (fat and grease) are first hydrolyzed to soluble products by extracellular enzymes, secreted by microorganisms, so as to facilitate their transport or diffusion across the cell membrane. These relatively simple, soluble compounds are fermented or anaerobically oxidized, further to short-chain fatty acids, alcohols, carbon dioxide, hydrogen, and ammonia. The short-chain fatty acids (other than acetate) are converted to acetate, hydrogen gas, and carbon dioxide. Methanogenesis finally occurs from the reduction of carbon dioxide and acetate by hydrogen. The initial stage of anaerobic degradation, i.e. acid fermentation is essentially a constant BOD stage because the organic molecules are only rearranged. The first stage does not stabilize the organics in the waste. However this step is essential for the initiation of second stage methane fermentation as it converts the organic material to a form, usable by the methane producing bacteria. The second reaction is initiated when anaerobic methane forming bacteria act upon the short chain organic acids produced in the 1st stage. Here these acids undergo methane fermentation with carbon dioxide acting as hydrogen acceptor and getting reduced to methane. The methane formed, being insoluble in water, escapes from the system and can be tapped and used as an energy source. The production and subsequent escape of methane causes the stabilization of the organic material. The methane-producing bacteria consist of several different groups. Each group has the ability to ferment only specific compounds. Therefore, the bacterial consortia in a methane producing system should include a number of different groups. When the rate of bacterial growth is considered, then the retention time of the solids becomes important parameter. The acid fermentation stage is faster as compared to the methane fermentation stage. This means that a sudden increase in the easily degradable organics will result in increased acid production with subsequent accumulation of acids. This inhibits the methanogenesis step. Acclimatization of the microorganisms to a substrate has been reported to take more than five weeks. Sufficiently acclimated bacteria have shown greater stability towards stress-inducing events such as hydraulic overloads, fluctuations in temperature, fluctuations in volatile acid and ammonia concentrations etc. Several environmental factors can affect anaerobic digestion, by altering the parameters such as specific growth rate, decay rate, gas production, substrate utilization, start-up and response to changes in input. It has long been recognized that an anaerobic process is in many ways ideal for wastewater treatment and has following merits: A high degree of waste stabilization A low production of excess A low nutrient requirements No oxygen requirement Production of methane gas Anaerobic microorganisms, especially methanogens have a slow growth rate. At lower HRTs, the possibility of washout of biomass is more prominent. This makes it difficult to maintain the effective number of useful microorganisms in the system. To maintain the population of anaerobes, large reactor volumes or higher HRTs are required. This may ultimately provide longer SRTs upto 20 days for high rate systems. Thus, provision of larger reactor volumes or higher HRTs ultimately lead to higher capital cost. Among notable disadvantages, it has low synthesis/reaction rate hence long start up periods and difficulty in recovery from upset conditions. Special attention is, therefore, warranted towards, controlling the factors that affect process adversely; important among them being environmental factors such as temperature, pH and concentration of toxic substances. The conventional anaerobic treatment process consists of a reactor containing waste and biological solids (bacteria) responsible for the digestion process. Concentrated waste (usually sewage sludge) can be added continuously or periodically (semi-batch operation), where it is mixed with the contents of the reactor. Theoretically, the conventional digester is operated as a once-through, completely mixed, reactor. In this particular mode of operation the hydraulic retention time (HRT) is equal to the solids retention time (SRT). Basically, the required process efficiency is related to the sludge retention time (SRT), and hence longer SRT provided, results in satisfactory population (by reproduction) for further waste stabilization. By reducing the hydraulic retention time (HRT) in the conventional mode reactor, the quantity of biological solids within the reactor is also decreased as the solids escape with the effluent. The limiting HRT is reached when the bacteria are removed from the reactor faster than they can grow. Methanogenic bacteria are slow growers and are considered the rate-limiting component in the anaerobic digestion process. The first anaerobic process developed, which separated the SRT from the HRT was the anaerobic contact process. In 1963, Young and McCarty (1968) began work, which eventually led to the development of the anaerobic upflow filter (AF) process. The anaerobic filter represented a significant advance in anaerobic waste treatment, since the filter can trap and maintain a high concentration of biological solids. By trapping these solids, long SRT's could be obtained at large waste flows, necessary to anaerobically treat low strength wastes at nominal temperatures economically. Another anaerobic process which relies on the development of biomass on the surfaces of a media is an expanded bed upflow reactor. The primary concept of the process consists of passing wastewater up through a bed of inert sand sized particles at sufficient velocities to fluidize and partially expand the sand bed. One of the more interesting new processes is the upflow anaerobic sludge blanket process (UASB), which was developed by Lettinga and his co-workers in Holland in the early 1970's. The key to the process was the discovery that anaerobic sludge inherently has superior flocculation and settling characteristics, provided the physical and chemical conditions for sludge flocculation are favorable. When these conditions are met, a high solids retention time (at high HRT loadings) can be achieved, with separation of the gas from the sludge solids. The UASB reactor is one of the reactor types with high loading capacity. It differs from other processes by the simplicity of its design. UASB process is a combination of physical & biological processes. The main feature of physical process is separation of solids and gases from the liquid and that of biological process is degradation of decomposable organic matter under anaerobic conditions. No separate settler with sludge return pump is required, as in the anaerobic contact process. There is no loss of reactor volume through filter or carrier material, as in the case with the anaerobic filter and fixed film reactor types, and there is no need for high rate effluent recirculation and concomitant pumping energy, as in the case with fluidized bed reactor. Anaerobic sludge inherently possesses good settling properties, provided the sludge is not exposed to heavy mechanical agitation. For this reason mechanical mixing is generally omitted in UASB-reactors. At high organic loading rates, the biogas production guarantees sufficient contact between substrate and biomass. Regarding the dynamic behaviour of the water phase UASB reactor approaches the completely mixed reactor. For achieving the required sufficient contact between sludge and wastewater, the UASB-system relies on the agitation brought about by the natural gas production and on an even feed inlet distribution at the bottom of the reactor. (ABSTRACT TRUNCATED)     

污泥中温厌氧消化的实验研究

通过实验室装置对活性污泥中温 (35℃) 厌氧消化过程中的沼气产生量和气体成分进行了监测,并对消化前后污泥的含水率、vS、成分等进行对比分析.结果表明:该污泥可以采用中温厌氧消化的方法进行处理,沼气的收集可以实现能量的回收,但由于消化后污泥中Cu、Ni的重金属含量超过GB 4284-1984 农用污泥中污染物控制标准,...     

The performance of UASB reactors treating high-strength wastewaters

In the study reported here, the authors investigated the influence of hydraulic loading rate, organic loading rate, and recycle rate on the performance of upflow anaerobic sludge blanket (UASB) reactors treating high-strength wastewaters. For this purpose, they used two identical reactors. The removal rates for chemical oxygen demand (COD), total kjeldahl nitrogen (TKN), total phosphorus (TP), total solids (TS), total suspended solids (TSS), and volatile solids (VS) were investigated for various hydraulic loading rates, and COD removal rates were investigated for various organic loading rates. In Reactor 1, a COD removal rate of 84.75 percent was achieved at influent COD of 8,000 mg/L and a hydraulic loading rate of 0.121 cubic meters per cubic meter per day (m3/m3-d). In Reactor 2, a COD removal rate of 82.83 percent was achieved at influent COD of 12,000 mg/L and a hydraulic loading rate of 0.069 m3/ m3-d. Although the COD removal rates of the reactors were high, TKN and TP removal rates were low. The removal rates usually decreased when hydraulic and organic loading rates were increased.     

Anaerobic degradation of linear alkylbenzene sulfonate

Linear alkylbenzene sulfonate (LAS) found in wastewater is removed in the wastewater treatment facilities by sorption and aerobic biodegradation. The anaerobic digestion of sewage sludge has not been shown to contribute to the removal. The concentration of LAS based on dry matter typically increases during anaerobic stabilization due to transformation of easily degradable organic matter. Hence, LAS is regarded as resistant to biodegradation under anaerobic conditions. We present data from a lab-scale semi-continuously stirred tank reactor (CSTR) spiked with linear dodecylbenzene sulfonate (C12 LAS), which show that C12 LAS was biodegradable under methanogenic conditions. Sorption of C12 LAS on sewage sludge was described with a Freundlich isotherm. The C12 LAS sorption was determined with different concentrations of total solids (TS). In the semi-continuously stirred tank reactor, 18% of the added C12 LAS was bioavailable and 20% was biotransformed when spiking with 100 mg/L of C12 LAS and a TS concentration of 14.2 mg/L. Enhanced bioavailability of C12 LAS was obtained in an upflow anaerobic sludge blanket (UASB) reactor inoculated with granular sludge and sewage sludge. Biodegradation under thermophilic conditions was 37% with LAS as sole carbon source. Benzaldehyde was produced in the UASB reactor during LAS transformation.