| By using forced aeration composting technique, sewage sludge and additives were composted. Effects of additive amount on sewage sludge composting, effects of matured sludge compost on sewage sludge composting and strengthened measures under the condition of low temperature were studied. The changing rules of physical, chemical and biological indexes were analyzed, so were the diversity and microbial population structure.In the study of effects of additive amount on sewage sludge composting, two composting piles were set. In the No.1 composting pile, the weight ratio of sewage sludge, rice straw and crop straw was 12:1:1 and that in the No.2 composting pile was 15:1:1, and the ventilation of the two composting piles were 5 m3·h-1·t-1. During composting, the temperature of the two composting piles rose smoothly and stayed over 50 for 5 days℃, which met the Hygienic requirements for harmless disposal of night soil(GB7959-2012). After composting, water content of the two composting piles were about 60% and organic matter content were about 40%. Both p H and NH4+-N of the two composting piles increased at first and then decreased, and total phosphorus content increased by 37.11% and 20.18% respectively. At the end of composting, GI of No.1 and No.2 composting pile were 125.57% and 112.51%. They were beneficial for seed germination and the former was more apparent. Physical and chemical indexes, pollutant indexes and poisonous indexes of the two composting piles met the Disposal of sludge from municipal wastewater treatment plant-Quality of sludge used in gardens or parks(GB/T 23486-2009), matured composting materials could be used in neutral and alkaline soil after being dried.In the study of effects of matured sludge compost on sewage sludge composting, three composting piles were set. The weight ratios of sewage sludge, rice straw, crop straw and matured sludge compost of No.1, No.2 and No.3 composting piles were 12:1:1:0, 12:1:1:4 and 12:1:1:6, and the ventilation of the two composting piles were 5 m3·h-1·t-1. The research showed that No.2 composting pile got the most appropriate temperature, which was better than No.1 composting pile, and No.3 composting pile didn’t met national standard. The effects of matured sludge compost on water content, organic matter content and EC were not apparent, and changing extend of p H value reduced with the increasing of amount of matured sludge compost. Adding matured sludge compost reduced the ammonia content(NH4+-N) in composting piles. After composting, GI of No.1, No.2 and No.3 composting piles were 110.55%, 105.97% and 109.97%, which were all beneficial for seed germination. When used as sludge used in gardens or parks, physical and chemical indexes, pollutant indexes and poisonous indexes of the No.1 and No.2 composting piles met the Disposal of sludge from municipal wastewater treatment plant-Quality of sludge used in gardens or parks(GB/T 23486-2009). Matured composting materials could be used in neutral and alkaline soil after being dried and their p H values should be regulated. High-throughput sequencing was used to analyze the diversity and the structure of microbial population. There were 34 groups in the distribution of 16 S r DNA by taxonomic phylum of composting samples at different stages, in which proteobacteria was the most important. The analysis of taxonomic class of No.1 and No.2 composting samples at different stages showed that Nitrospira, Bacilli, Clostridia, Actinobacteria, Sphingobacteria and Verrucomicrobiae varied regularly. Adding matured sludge compost affected the composition and content of microorganisms to some extent, but its effects on the variation trend of microorganisms at different composting stages were not apparent.In the study of strengthened measures under the condition of low temperature, three composting piles were set. The weight ratios of sewage sludge, rice straw, crop straw of No.1, No.2 and No.3 composting piles were 12:1:1, 12:1:1 and 6:1:1. No.1 composting pile was equipped with water bath of 30 ℃and ventilation of No.3 composting pile was 10 m3·h-1·t-1. During composting, temperature of No.1 composting pile kept over 40 ℃for a period, and that of No.2 and No.3 composting piles were relatively low. The variety of water content, organic matter content, p H value and EC of No.1 composting pile was more obvious than No.2 and No.3 composting piles. After composting, the ammonia content(NH4+-N) were 1.564 mg/g, 0.634 mg/g and 0.630 mg/g respectively, and GI were 79.53%, 79.10% and 77.60% respectively. Water bath of 30 improved ℃the effectiveness of composting, while increasing ventilation and amount of additives did not. High-throughput sequencing was used to analyze the diversity and the structure of microbial population. There were 34 groups in the distribution of 16 S r DNA by taxonomic phylum of composting samples at different stages, in which proteobacteria was the most important. The analysis of taxonomic class of No.2 and No.3 composting samples at different stages showed that Nitrospira, Bacilli, Clostridia, Actinobacteria, Sphingobacteria and Verrucomicrobiae varied regularly. Under the condition of low temperature, increasing amount of additives and ventilation could affect the composition and content of microorganisms in composting piles. |
PDF Full Text Request