微丝菌型污泥膨胀的工艺负荷调控方法

提出调控工艺局部污泥负荷分布来处理污水处理厂冬季微丝菌污泥膨胀。在某AAO工艺污水处理厂开展平行反应器实验,进行显微观测和工艺模拟,发现反应器前端厌/缺氧区污泥去除负荷的差值与微丝菌丰度、污泥粒径和沉降性能有相关性。比较多种运行模式的改善效果,发现AO模式沉降性能最好,优于AAO和多点回流。反应器前端污泥去除负荷梯度可作为调控指标,实验中AO模式负荷梯度可达0.54 kg COD·（kg SS·d）-1,明显高于AAO、多点回流和多点进水。因此,通过优化回流和排泥操作,可以调控污泥去除负荷的沿程分布,有可能缓解冬季的微丝菌型污泥膨胀。     

厌氧颗粒污泥反应器对丙酸和丁酸冲击负荷变化的响应研究

采用升流式厌氧污泥床（UASB）反应器,对增大进水浓度和增大进水流量过程中,颗粒污泥对丙酸和丁酸冲击负荷变化响应进行了研究。实验表明,进水浓度从2 000 mg COD/L提高到5 000 mg COD/L,丙酸去除率骤降,而丁酸降解相对稳定;在保持进水浓度为3 000 mg COD/L的条件下,增大进水流量,负荷从7.5 kg COD/（m3.d）升高到15 kg COD/（m3.d）时,丙酸降解率骤降,丁酸降解率仍然相对稳定。实验结果符合降解热力学理论和传统抑制动力学的未解离挥发性脂肪酸理论,并发现改变反应器运行条件能够加剧未解离酸的抑制作用。同时提出了探讨厌氧过程中丙酸积累导致厌氧反应器运行失败的基础理论原因。     

Application of anaerobic and aerobic activated sludge to phosphorus-deficient wastewater treatment.

Anaerobic and aerobic (AnA) and completely aerobic (CA) sequencing-batch reactors (SBRs) were used to investigate the suitability of the AnA process for treating phosphorus (P)-deficient wastewaters with highly variable influent chemical oxygen demand (COD) loading. Both SBRs were subjected to influent COD loading patterns (LPs) that simulated (1) daily COD loading fluctuations, (2) weekend shutdowns, and (3) long weekend or holiday shutdowns. During LP 1, the AnA SBR produced lower average effluent soluble phosphorus concentrations than CA SBR (0.4 vs. 1.0 mgP/L). A similar result was observed during LP 2, but effluent acetate was detected after the first high COD loading cycle of the weekday loading period. During LP 3, the volatile suspended solids content of both reactors dropped sharply, and the effluent quality of both SBRs deteriorated. Model predictions suggest that the AnA process is stable when treating LP 1, but eventually fails when treating LP 2.     

Acclimatisation to nitrilotriacetic and in the activated sludge process

The period of acclimatisation prior to the biodegradation of nitrilotriacetic acid in an activated sludge pilot plant was studied in a series of experiments. The effects of low and high influent heavy metals concentrations upon acclimatisation are reported.     

剩余污泥混合对絮凝污泥厌氧消化的强化

为了考察絮凝污泥与剩余活性污泥混合中温(35℃)厌氧消化效果,分析了不同混合比例、不同投配率下的总化学需氧量(TCOD)去除率、挥发性固体(VS)降解效果,通过pH值与氨氮浓度的变化来分析各反应器的稳定性。结果表明:污泥混合后消化效果明显得到提高,且污泥消化效率随着投配率的增加先提高后下降。5%投配率时,絮凝污泥/剩余污泥(VS比)为1:2时厌氧消化效果最好,TCOD去除率达到47.8%,VS降解率达到46.8%,分解单位VS产气量达到了435 mL/g,pH值与氨氮浓度分别保持在7.4和269 mg/L左右,混合污泥厌氧消化系统较稳定。这说明与剩余污泥的混合消化能有效提高絮凝污泥的厌氧消化性能。污泥絮体的显微分析表明:厌氧消化过程中絮体面积百分比逐步减小,污泥结构逐步解体,可以解释污泥消化的微观过程。     

Assessing microbial communities for a metabolic profile similar to activated sludge.

To search for reliable testing inocula alternatives to activated sludge cultures, several model microbial consortia were compared with activated sludge populations for their functional diversity. The evaluation of the metabolic potential of these mixed inocula was performed using the Biolog EcoPlates and GN and GP MicroPlates (Biolog, Inc., Hayward, California). The community-level physiological profiles (CLPPs) obtained for model communities and activated sludge samples were analyzed by principal component analysis and hierarchic clustering methods, to evaluate the ability of Biolog plates to distinguish among the different microbial communities. The effect of different inocula preparation methodologies on the community structure was also studied. The CLPPs obtained with EcoPlates and GN MicroPlates showed that EcoPlates are suitable to screen communities with a metabolic profile similar to activated sludge. New, well-defined, standardized, and safe inocula presenting the same metabolic community profile as activated sludge were selected and can be tested as surrogate cultures in activated-sludge-based bioassays.     

Effects of sludge properties on the thickening and dewatering of waste activated sludge.

The thickening and dewatering of waste activated sludge, from a pilot-scale submerged membrane bioreactor and two bench-scale, complete-mix activated sludge reactors (high-shear and low-shear aeration) treating the same municipal primary effluent, were investigated. Solids settling and compaction were measured using the diluted sludge volume index (DSVI) analysis and a batch centrifugation analysis, respectively. Elevated levels of filamentous microorganisms resulted in higher DSVI values and lower centrifuged pellet concentration. Elevated levels of nocardioform bacteria resulted in lower solids float concentrations, and higher colloidal material reduced solids recovery in batch flotation experiments. Sludge filterability, measured as time-to-filter, was shown to be a function of extracelluar polymeric substances and colloidal material, where higher levels of either reduced sludge filterability. Additional research is necessary to confirm these results using full- or demonstration-scale thickening and dewatering units.     

Maximum nitrogen removal in the step-feed activated sludge process.

This paper presents a mathematical framework that can be used to determine the flow distributions for a step-feed activated sludge process that result in maximum nitrogen removal. The model indicates that nitrogen removal efficiency in a step-feed activated sludge process is highly dependent on the ultimate biochemical oxygen demand (BOD(L))-to-total Kjeldahl nitrogen (TKN) ratio of the wastewater. For typical domestic wastewater, which has a relatively high BOD(L)-to-TKN ratio, the step-feed process will outperform the Modified Ludzack-Ettinger process for nitrogen removal, when the flow to each step is optimally distributed. Using plant-specific water quality data and operating conditions from a 1-year period, nitrogen removal performance for four step-feed activated sludge plants operated by the Sanitation Districts of Los Angeles County (California) was calculated using the developed model. The calculated nitrogen removal efficiencies match well with the actual plant performance data. These results validate the model as a useful tool for predicting nitrogen removal in a step-feed activated sludge process. Other analyses revealed that improvements in nitrogen removal at existing facilities are achievable by adjusting the split of primary effluent flow to each anoxic zone several times during the day. The timing of the adjustments and the optimal flow splits can be determined from data on diurnal fluctuations in BOD(L) and TKN concentrations. An example is provided to illustrate the application of such an operating strategy and the potential enhancement of nitrogen removal.     

Chemically reduced excess sludge production in the activated sludge process

Excess sludge production from wastewater biological treatment process is highly, and the disposal of excess sludge will be forbidden in a near future, thus increased attention has been turned to look into potential technology for sludge reduction. Recently, some novel sludge reduction techniques have been developed based on chemical oxidation and metabolic uncoupling. This paper attempts to review those chemical-assisted sludge reduction processes, including sludge alkaline-thermal treatment, activated sludge-ozonation process, chlorination-combined activated sludge process, sludge reduction by metabolic uncouplers and high dissolved oxygen activated sludge process. In these combined activated sludge processes, excess sludge production can be reduced up to 100% without significant effect on process efficiency and stability. This paper would be useful when one is looking for appropriate environmentally and economically acceptable solutions for reducing or minimizing excess sludge production from wastewater biological treatment process.     

Filamentous scum bacteria in activated sludge plants: detection and identification quality by conventional activated sludge microscopy versus fluorescence in situ hybridization.

Detection of filamentous bacteria morphotypes involved in scum formation in activated sludge wastewater treatment plants by conventional sludge microscopy is often doomed to fail because of morphological and taxonomical variations. The aim of this study is to compare detection, identification, and quantification quality of filamentous "scum bacteria" found by conventional activated sludge microscopy and fluorescence in situ hybridization (FISH). In the case of filamentous Microthrix parvicella and Eikelboom morphotypes 1863 and 1851, conventional activated sludge microscopy and FISH results correspond well. In contrast, conventional activated sludge microscopy overlooks nocardioform actinomycete and type 1863 single cells. On the other hand, FISH underestimates filamentous nocardioform actinomycetes and morphotypes 0041/0675 or 0092 because of insufficient cell wall permeability or because of their taxonomic variability, with a resulting inadequacy of previously published probes. Nostocoida limicola morphotype results are still inconclusive because of low bacteria numbers being available in situ and the enormous taxonomic variability within this group.