Sewage Treatment Plant Sludge Conditioning Research And Application

In China, as with the increasing treatment rate of municipal wastewater, the amount of municipal sludge generated is increasing drastically. In those cities with high level of urbanization in particular, the substantial amount of waste sludge has posed a negative effect on the development of the city and the well-beings of the society, which has become a heated problem that calls for urgent solutions. For example, in Guangzhou city, the wastewater treatment capacity has reached 4.75 million tons per day and sludge treatment capacity 2700 tons per day. Due to its high water content in waste sludge(about 80%), which has already exceeded the maximum treatment capacity in wastewater treatment plants in Guangzhou, a substantial amount of sludge lacks proper handling measures. Therefore, it is imperative to attain sludge reduction.Based on our research, which adopts single-factor and combined-multiple-factors approaches, we concluded that the addition of lime(Ca O), ferric chloride(Fe Cl3) and polyacrylamide(PAM) yields optimum results. When 1% of PAM, 15-20% of Ca O and 15-20% of Fe Cl3 are added, SRF(specific cake resistance) of the sludge is the low. More specifically, when 1% of PAM, 17.5% of Ca O and 17.5% of Fe Cl3 are added into the dried sludge, the resulting SRF reaches its lowest point: 0.071 cm/g. The cost of treating dried sludge is 174.75 RMB/ton. After adopting this approach in Guangzhou Zengcheng wastewater and wastewater sludge dewatering process, which uses filter press machines(pressure filter) the waster content was kept below 55%.This research was conducted using equipment, dewatering chemicals and experiment labs provided by Guangzhou Zengcheng wastewater treatment plant to examine the effectiveness of dewatering chemicals with different compositions. This research has provided valuable experiment data in terms of keeping waster content below 55%, improving dewatering efficiency,,lowering sludge dewatering costs and at the same time and most importantly, attaining sludge reduction.