Experimental investigation of phosphorus adsorption capacity of the waterworks sludges from five cities in China

The potential application of waste sludge from drinking water plant as low-cost adsorbent and alternative substrate in constructed treatment wetland has been proposed and studied in recent years. But in China study of waterworks sludge as adsorbent is lack. More significantly, China is a huge country and the sludges generated from waterworks may be significantly different in characteristics by the nature of raw waters treated. This study was to investigate the phosphorus adsorption capacity of different kinds of sludges from five waterworks in different cities of China. The main issues focused on were: (1) characteristics of the different waterworks sludge from different water sources and coagulants, (2) phosphorus adsorption capacity of different kinds of sludges and (3) life expectancy estimation of waterworks sludge as adsorption substrate. The tests on P-adsorption show that the maximum P adsorption capacities of sludge samples from Shijiazhuang, Chengdu, Liupanshui, Suzhou and Taiyuan are 20,408 mg-P/kg, 15,625 mg-P/kg, 15,385 mg-P/kg, 90,909 mg-P/kg and 4167 mg-P/kg, respectively. The theoretical calculation of life expectation of sludge phosphorus adsorption based on the proposed conditions was conducted. The results show that all the sludges have good adsorption capacity for phosphorus. It could be concluded that the sludge from waterworks has great potentials in China for P-adsorption.