Recovery of coagulant from water supply plant sludge and its effect on clarification

Abstract

Spent coagulant in water supply plant sludge was extracted with H 2 SO 4 and the effi ciency of the reused coagulant was studied. The optimum pH values for coagulant extraction and clarifi cation with the reused coagulant were 3.0-4.0 and about 6, respectively. In treating raw infl uent obtained from a sewage treatment plant and wastewater from a coastal landfi ll site, the removal of chemical oxygen demand (COD), total nitrogen, and total phosphorous with the recovered coagulant was higher than that with commercial aluminum sulfate or polyaluminum chloride. In addition, the sludge settling properties, the extra sludge mass formation, the supernatant quality, and the cost of reagents were also studied. The coagulant recovered from water supply plant sludge by H 2 SO 4 extraction could be successfully reused for the clarifi cation of domestic and food industry wastewaters. Key words Water supply plant sludge · Recovery and reuse of coagulant · Clarifi cation · COD · Nutrients Materials and methods SamplesClarifi er sludge (water content, 69.3%; ignition loss, 10 27.7%) from a municipal water supply plant was used for the recovery of coagulant. The plant uses Al 2 (SO 4 ) 3 and PACl coagulants. 11 Raw infl uent (pH, 7.5; COD, 44.0-79.6 mg/l; T-N, 31.4-33.0 mg/l; T-P, 2.70-3.29 mg/l) from a J Mater Cycles Waste Manag (2007) 9: [167][168][169][170][171][172]

Utilization of Drinking Water Treatment Slurry to Produce Aluminum Sulfate Coagulant

“…Due to regulatory changes, WTS now has to be disposed of in landfills or through land application in developed countries however, in developing countries, it is disposed into water bodies or sanitary sewers (Nair and Ahammed, 2015). WTS discharged into water bodies is reported to be toxic to aquatic life (Evuti and Lawal, 2011) since the levels of pollutants in WTS are relatively low, as the best quality raw water sources are generally selected for drinking water production (Ishikawa et al, 2007), the reuse of WTS may be a feasible option. A number of research efforts have been made particularly in recent years to use WTS in many beneficial ways which include its uses in building and construction materials (Monteiro et al, 2008;Pan et al, 2004), in wastewater treatment (Babatunde and Zhao, 2010;Moghaddam et al, 2010;Nair and Ahammed, 2015) and for soil improvement (Hovsepyan and Bonzongo, 2009).…”

“…In the second approach, wet/dry sludge itself is used as a coagulant or adsorbent for removal of different contaminants. Recovery of coagulant metal from WTS is an attractive option and has been reported by many researchers Ishikawa et al, 2007;Xu et al, 2009). Generally, four ways of coagulant recovery are employed for the WTS, which includes acidifica-tion, basification, ion exchanging, and membrane processes (Xu et al, 2009).…”

Application of waterworks sludge in wastewater treatment plants

“…Waterworks sludge (WWS) (e.g. Babatunde and Zhao 2007;Ippolito et al 2011;Ishikawa et al 2007), fly ash (Yan et al 2007), red mud (e.g. citation in Liu et al 2011), blast furnace slag (e.g.…”

Water treatment sludge for phosphate removal from the effluent of UASB reactor treating municipal wastewater

“…A pH range of 6-9 was used in the study in order to reduce chemical consumption during coagulation and subsequent neutralisation before disposal of treated effluent. Further, high acidic or alkaline pH causes resolubility of metals from WTS (Ishikawa et al, 2007). The experimental design matrix for BBD is presented in Table 4.…”