Experimental Study on Minimization of Sludge Production by Ozonation Process

Based on the hypothesis of reducing sludge production under cryptic growth conditions, ozone was used as cell lysis agent to treat excess sludge, and then the ozonated supernatant was returned to. the aeration tank. The results show that COD and NH4+-N removal efficiencies in ozonation process were 87.96% and 84.42%, respectively. Meanwhile, a low excess sludge yield coefficient of 0.113 (g SS/g COD removed) was obtained. Compared with that of the control test, the process configuration decreased the excess sludge production by 51.3%.     

Analysis of Circumstance Influence Factors on HMBR for Waste-water Reclamation in Dwelling District

Circumstance influence factors on Hybrid Membrane Bio-Reactor (HMBR) process for the wastewater reclamation in dwelling district was analyzed. The main characteristic of this process is that sludge and nitrified effluent can be recycled automatically, which simplifies the operation of system and is beneficial to get the high removal of organics and nitrogen. Based on the analysis of circumstance influence factors, it is recommended that water temperature of about 20℃, influent pH of 6 -7 and DO of 1. 0 mg/L - 1. 5 mg/L in the aerobic compartment. Under these conditions, COD, BOD5, NH4+ -N, and TN were removed effectively in HMBR and the average removal efficiencies were 94.5%, 99.3%, 99.4% and 84.7%, respectively. SS and coliforms were both below the detection limits in the permeate of UF membrane module, and turbidity was less than 1NTU. The treated effluent meets the Miscellaneous Domestic Water Quality Standard (CJ25.1-89), and can be reused multipurposely such as watering of green belts, cleaning a     

Implementing Both Domestic Wastewater Reuse and Sludge Reduction by a Combination of Anaerobic Phase and Membrane bioreactor

The aim of the research was to obtain both an excellent effluent for reuse and a reduced sludge production simultaneously by a combination process of anaerobic phase and Membrane bioreactor （MBR） technology in treating domestic wastewater. During the experimental period of three months, excellent removals for COD, NH3-H, TN were obtained, and mean removals were 91.87%, 96.13%, and 69. 23%, respectively. Whereas, at first 20 days, the removal for TP was only about 15.87%. In the following days, about 30% of raw water was introduced into the anaerobic reactor to supply organics for denitrificatien and release of polyphosphate, then a significant improvement for TP removal was observed, and mean removal of TP increased to 76.35%. During the operational period, it was investigated that the permeate could meet the requirements of several water criteria for reuse except free chlorine, and a mean excess sludge yield coefficient of 0.137 g MLSS/g COD was obtained. Therefore, the predicted goals of permeate for reuse and excess sludge reduction could be both achieved after dosing a certain quantity of disinfectant into the permeate.     

Enhanced Biological Phosphorus Removal in SBR Using Glucose as a Single Organic Substrate

Enhanced biological phosphorus removal （EBPR） was investigated in an anaerobic/aerobic sequencing batch reactor （SBR） supplied with glucose as a single organic substrate. The results illustrated that EBPR process could also occur successfully with glucose other than short chain fatty acids （SCFAs）. High phosphorus release and polyhydroxyalkanoate （PHA） accumulation in the anaerobic phase was found vital for the removal of phosphorus during the aerobic phase. The measurement of intracellular reserves revealed that glycogen had a higher chance to replace the energy role of poly-P under anaerobic conditions. Moreover, glycogen was also utilized as the carbon source for PHA synthesis, as well as a reducing power as reported earlier. The accumulated PHA in this system was mainly in the form of poly-hydroxyvalerate （PHV） instead of poly-hydroxybutyrate （PHB）, and was inferred to be caused by the excess reducing power contained in glucose. Lactate as a fermentation product was also found released into the bulk solution. Applying fundamental biochemistry knowledge to the experimental results, a conceptual biochemical model was developed to explain the metabolism of the glucoseinduced EBPR.     

塘-湿地组合处理系统中磷的主导去除机制分析

为确定环境差异对磷去除机制影响,利用组合塘-湿地生态处理系统中各单元环境与磷形态分布的差异,分析各单元磷的主导去除机制及其对底泥和水体中磷迁移过程的影响.结果表明：悬浮磷沉积、溶解无机磷的吸附/络合和悬浮磷的截滤依次为各单元磷的主导去除机制.磷主导去除机制的差异决定了各单元底泥中磷分布遵循一定的规律性和特殊性.此外,低温期悬浮磷的沉积作用除磷效率高;高温期溶解无机磷的吸收/络合作用除磷效率高.因而,水环境差异对生态处理系统中磷去除规律影响明显.     

Activated Sludge Ozonation to Reduce Sludge Production in MBR

The total experimental period was divided into two stages. At the first stage, a series of batch studies were carried out to get an understanding of the effect of ozouation on sludge properties. At the following stages, three MBRs with different amounts of activated sludge to be ozonated were run in parallel for a long period to evaluate the influence of sludge ozonation on sludge yield and permeate quality. Through batch study, it was found that ozone could disrupt the cell walls and caused the release of plasm from the cells, then the amounts of soluble organics in the solution increased with ozouation time. With the rise of soluble organics, the amount of soluble organics to be mineralized increased as well, which would reduce the soluble organics content. For the counteraction between these two aspects, a pseudo-balanee could be achieved, and soluble organics would vary in a limited range. Sludge ozonation also increased the contents of nitrogen and phosphorus in the solution. In addition, ozouation was effective in improving sludge settling property. On the basis of batch study, a suitable ozone dosage of 0.16 kgO3/kgMLSS was determined. Three systems were run in parallel for a total period of 39 days, it was demonstrated that a part of activated sludge ozonation could reduce sludge production significantly, and biological perfonnanee of mineralization and nitrification would not be inhibited due to sludge ozouation. Experimental results proved that the combination of ozonation unit with MBR unit could achieve an excellent quality of permeate as well as a small quantity of sludge production, and economic analysis indicated that an additional ozonation operating cost for treatment of both wastewater and sludge was only 0.096Yuan （US$ 0.011,5 ）/m^3 wastewater.