Research On The Process Of Sludge Reduction By Tubificidae

With the wide application of biological treatment technology in sewage treatment Plants, large amounts of waste sludge are Produced. However, the cost of processing the sludge can account for25%to65%of the sewage treatment plant, so the treatment and disposal of excess sludge has become a heavy burden of the sewage treatment plant. Conventional sludge treatment method not only takes a lot of manpower and material resources, and if disposed of improperly, it maybe cause secondary pollution on the environment. Sludge reduction by predation of creatures requires a little energy and brings no second Pollution, it achieving source control of sludge.Currently, the Phoenix River2nd-Ditch sewage treatment plant uses the system that include the pretreatment-Constructed Rapid Infiltration-artificial wetland to treat sewage, Constructed Rapid Infiltration will clog and its life will reduced due to long-term operation make it intercept a large amount of debris and sludge, So it is necessary to plow and clean up the sludge regularly. This will increase the running costs of the wastewater treatment plant, and the whereabouts of the sludge is a problem, this has become a heavy burden faced by the wastewater treatment plant. Based on above reasons, this thesis, taking Limnodrilus hoffmeisteri as the research object after researching its basic characteristics, use the in-situ tubificidae sewage sludge digestion technology to reconstruct in ChengDu, Monitoring experiments to analyze the sludge reduction efficiency and water quality.The research showed that tubificidae grow well in the system, its density is maintained at about1.2g/L, As its density increases, the greater the amount of sludge reduction, and it can reach around100mg/L; Sludge Reduction increased with increasing temperature in the range of5～20℃,Within20to25℃C range is reduced as the temperature rises, About20℃the reduction effect is best, sludge reduction can be achieved to127.20mg/L, at5℃low life activities of tubificidae, it feed small amount of sludge, sludge reduction can be achieved 85.54mg/L; When the DO is2～4mg/L, the best sludge reduction effect can be reached100.54mg/L; As the influent concentration of COD and SS increases, the amount of sludge reduction increases, reductions to45.49mg/L～184.53mg/L, But the rate of sludge reduction by tubificidae is maintained at60to80%, This shows the extent of the fluctuations of tubificidae on the degradation rate of the sludge as the water load is small, while the amount of sludge digestion changed greatly.Under the influence of a combination of factors, the rate of sludge reduction by tubificidae can be maintained in the52.43to85.9%, the reductions to between64.20mg/L-169.84mg/L, the reduction rate of reduction in the summer than in winter, clipping rate is still able to maintain more than50%in winter. This shows that sludge reduction by tubificidae in normal circumstances, maintain the temperature at4℃C to30℃C, DO from2to4mg/L, the population density of about1.2g/L, the COD in the50to500mg/L, tubificidae can have a better sludge digestion results, show that the in-situ sewage sludge digestion technology has better adaptability, able to achieve the purpose of sludge digestion at the source.