Microbial Agents On The Reduction Of Sewage Sludge

Recently, there are more concern about the wastewater treatment. As a result, the deal efficiency and amount of treated wastewater increased much fast. The conventional activated sludge (CAS) process is the most widely used biological treatment process for both domestic and industrial waste streams. However, one of its drawbacks is high sludge production. As the environmental and legislative requirements on the discharge of excess sludge produced during the biological treatment of wastewater have been strengthened, The disposal of excess sludge is strongly limited. There are many harmful components in sludge including pathogenic matter, heavy metals and residual organic matter, which could pollut the environment if the sludge doesn't treat properly. To resolve the sludge problem, there are two directions. One is to promote the treatment technical which stabilized sludge. The other is to reduce the production of excess sludge during the wastewater treatment. It is hard to stabilize excess sludge completely. Because of the technical and economy limits, the sludge treatment can not avaid the negative effect to the environment. In 1990's, a new idea were brought forward that is reducing the sludge production during the wastewater treatment. Reviewed the technical and the theory on sludge reduction of past and present, this has given an impetus to the search for new strategies for excess sludge reduction in biological wastewater treatment processes. Depending on the production principle of excess activated sludge in biological treatment processes, possible approaches to sludge reduction may include three aspects: uncoupling metabolism, cryptic growth enhanced through cell lysis, and micro-fauna predation. In this work, bench scale sequencing batch reactors (SBRs) with the MCMP (Multifunctional Compound Micro-organisms Preparation) were applied to the aerobic bio-degradation of excess sludge under the wastewater treatment conditions and emphasize research on the MCMP use. The results of research are below:1) This paper studies the influence to sludge reduction effect of three Micro-organisms Preparation: the Bacillus, the EM and the MCMP. The MCMP is the best to sludge reduction effect on the wastewater treatment.And then, studies the influence to wastewater sludge reduction effect caused by wastewater COD concentration, wastewater retention time (t) and temperature(T) of wastewater and the MCMP adding dose in the SBR process. And the results are wastewater retention time > the MCMP adding dose > temperature(T) of wastewater > wastewater COD concentration. The experiments of the MCMP adding dose and the excess sludge production in the SBR process, The results showed that the better MCMP adding dose is 5×10^-5(V/V).2) The pilot-plant experiments of the jiang jin and the changshou wastewater treatment plant for daily flow of 5m³/d were carried out to determine the effect of MCMP inoculation on the excess sludge reduction during wastewater treatment process. The MCMP adding dose being 0.02% and 0.04% of the influent flow, The results showed that: A.Continous experiment on the jiangjin wastewater treatment plant of 62 days test, and no excess sludge had been discharged in the wasterwater treatment system during about four months operation. Influent and Enfluent quality of the jiangjin wasterwater treatment plant and the experiment results are similiar in. B. Continous experiment on the changshou wastewater treatment plant of 90 days test, The MCMP adding dose being 0.005% and 0.01% of the influent flow, The reduction of sludge in wastewater treatment facilities is 81.76% and 89.18%. The TN and TP had been reduced somehow. This method needed no changes for wasterwater treatment process and operation pattern, The extra consumption of power was also needless. The negative impact on qulity of effluent was hardly any.and The cost for disposal of excess sludge in wasterwater treatment plant has been accounted. The cost was cheapter than the MCMP adding before. It is about 0.02 yuan (RMB) /m³.3) The continuous plant-scale experiment was carried out at Degan Municipal Wastewater Treatment Plant (WWTP), which located in Jiangjin District of Chongqing, to investigate the effect of excess sludge of reduction by MCMP inoculation. The results indicated that when adding MCMP into the aerobic part of oxidation ditch with 0.005% of daily Wastewater treatment flow, and adding once a month, the production of sludge had been reduced observably. No excess sludge of treatment system had been discharged for 6 months. The addition of MCMP had not only ensured the water quality of treated effluent to be up to first-class B of "Discharge standard of pollutants for municipal wastewater treatment plant"(GB18918-2002), but also achieved the removal of N and P effectively. Based on surveying the content of heavy metals, the T-Hg is about 81% higher, the TAs is about 110% higher, the TNi is 46% higher, the TK is 24% higher, the TP is 7% higher, the TCr is 64% lower, the TN is 29% lower. The MLVSS/MLSS is lower. The SVI value is from 19.3 to 26.23. This method needed no changes for wastewater treatment process and operation pattern, the extra consumption of power was also needlessness. The tremendous economic benefits, public benefits and environmental benefits can be obtained.4) Through the ERIC-PCR fingerprints of activated sludge and Morphology of activated sludge under microscope during the influence to wastewater sludge reduction effect experiment, the results show that the ERIC-PCR fingerprints have been indicated that the inherit of bacteria in the activated sludge is succession. It means that the microorganism community characterization of in activated sludge is changed. Some bacteria rate in activated sludge ecosystem are more than the MCMP addition before, and some of them are disappeared. The MCMP influenced the microbial component in the activated sludge particles, and the sludge characteristics were changed. Compared with the control sludge, the activated sludge particals become harder than the MCMP addition before, and the activated sludge partical's number is increased. The changed in morphology of activated sludge floc give different environmental conditions for kinds of bacteria, with the changes of the microbial component in activated sludge community ,some dominant populations are appeared in a fit environmental condition. So the functions of the activated sludge floc is changed, some new functions was come up.5) Based on the micro-equilibrium community theory of the ecology, there are some ways to enhance micro-organisms community function of the activated sludge. Through add an artificial efficient bacteria in the activated sludge process quickly, the microorganisms community was changed in succession, so that the function of the activated sludge had been strengthened. It is clear that the activated sludge process of the wastewater treatment factory had been enhanced by the MCMP add, and the activated sludge microorganisms community structure in the ecosystem was changed. As a result, the excess sludge reducing rate had been enhanced, and it had promoted pollutant reduced in a high efficiently. The applied process of the MCMP is very simple, and it has only need to add the MCMP in the activated sludge process directly. The cost of the MCMP add to reduce excess sludge is lower than to add before. It is a sustainable developmental way to reduce excess sludge in wastewater treatment plant by the MCMP add.