[Nutrient contents and heavy metal pollutions in composted sewage sludge from different municipal wastewater treatment plants in Beijing region].

Changes of nutrient contents and heavy metal pollutions in composted sewage sludge from different municipal wastewater treatment plants (as represented by CSS-A and CSS-B, respectively) in Beijing region were investigated. The results showed that the pH values, nutrient contents, trace elements and heavy metals in CSS-A and CSS-B depended on the sludge resources and particular years. The average of organic matter content in different years (203 338.0 mg x kg(-1)) from CSS-A met both the requirement of sludge quality standard for agricultural use (CJ/T 309-2009) and land improvement (GB/T 24600-2009) in China except the permitted limit of sludge quality standards for garden or park use (GB/T 23486-2009) in China. Moreover, the average of organic matter in different years (298531.5 mg x kg(-1)) from CSS-B and the averages of pH values (7.1 and 7.2, respectively) and NPK concentrations (41 111.7 mg x kg(-1) and 65 901.5 mg x kg(-1), respectively) in different years from CSS-A and CSS-B all met the requirements of sludge quality standards for the above-mentioned disposal types of sewage sludge from municipal wastewater treatment plants. The contents of heavy metals in CSS-A and CSS-B except Hg and Ni were below the permitted limits of the A-class sludge quality standard for agricultural use (CJ/T 309-2009) , being the most stringent standards in China. It was suggested that composted sewage sludge from different municipal wastewater treatment plants in Beijing region use as a fertilizer in agriculture, land improvement, and garden or park, but the top concern about potential environmental pollution of Hg and Ni should be considered.