Harmless disposal and resource utilization of wastes from the lake in China: Dewatering, composting and safety evaluation of fertilizer

Abstract

Abstract Removal of waste (cyanobacteria, macrophytes and sediment) from Chaohu Lake, a large freshwater lake in China, might cause secondary environmental pollution due to improper disposal. Bioleaching dewatering and composting were performed in this study to dispose these wastes. The results showed that bioleaching could effectively decrease the water content in the cyanobacteria-macrophytes-sediment mixture. The reduced nitrogen-loss rate and increased humus content were observed in the compost after inoculating with microbial agent. High-throughput DNA sequencing showed that the microbial inoculants influenced microbial community composition. The degradation rates of microcystin variant with leucine (MC-LR) and microcystin variant with arginine (MC-RR) in the treatment of composting plus microbial inoculation were significantly higher than those in the natural placement. Seeds of Chinese cabbage were grown in the soil supplemented with mature compost for 67\u202fdays. The content of heavy metals in the organic fertilizer, soil and cabbage were much lower than the corresponding limited values of the national standard in China. In conclusion, the cyanobacteria, macrophytes and sediment in China Chaohu Lake could be used safely as raw materials for composting.