Physical And Chemical Properties And Bacterial Diversity Of Different Landfill Age Refuse

Most domestic landfills in China are facing the problems of service expiration or early closure.And these landfills contain large quantities of different landfill age refuse.How to mine and utilize these refuse is the key to achieving sustainable use of landfills.Based on these circumstances,this paper took the Qingdao Xiaojianxi Landfill as an example.The physical composition and stabilization characteristics of different landfill refuse were studied.And based on high-throughput sequencing technology,the bacterial diversity and community structure among different landfill age refuse were analyzed.In order to provide a theoretical basis for the exploitation and resource utilization of different landfill age refuse.The main conclusions are as follows:(1)The physical composition of the refuse showed that,with the increased of landfill age,the proportion of combustibles(>3cm)in the refuse gradually decreased and the proportion of fine materials(<1cm)gradually increased.Fly ash and original refuse mixed area in the landfill,the average proportion of combustibles(>3cm)of 0~1 years and 1~3 years is lower than that in original refuse area.(2)The results of physical and chemical properties of landfill refuse and leachate indicated that,with the increased of landfill age,the moisture content,organic matter,volatile matter,electrical conductivity and Kjeldahl nitrogen of the refuse showed a decreasing trend.And the pH and soluble phosphorus content increased.There were certain differences of physical and chemical properties between the mixed refuse area and the original refuse areas.These were due to the fact that the high alkalinity and high salinity of fly ash had an impact on the physical and chemical properties of the refuse.Among the leachate in different landfill ages,the physical and chemical properties were similar to those of the refuse.In general,Qingdao Xiaojianxi Landfill is still in a very unstable stage.(3)The diversity of bacterial communities in different landfill ages refuse indicated that,with similar landfill age,bacterial community composition had high similarity in the refuse.And the bacterial community in different landfill ages continued to undergo succession changed.As time gone on,the diversity of bacterial communities showed an increasing trend first.When the refuse reached a certain degree of stabilization,the bacterial community diversity had decreased.(4)The structure of bacterial communities in different landfill ages refuse showed that,in the process of refuse degradation,the bacteria involved in the degradation mainly include Proteobacteria,Firmicutes and Bacteroidetes.Proteobacteria had an absolute advantage.With the stabilization of refuse,the abundance of Firmicutes gradually decreased,and the abundance of Bacteroidetes gradually increased.The dominant genus involved in the degradation were Pseudomonas,Thiopseudomonas,Psychrobacter,Desemzia and Aliidiomarina.As the refuse degradation progresses,their abundance also changes regularly.The bacterial abundance of the Bacillus in the Firmicutes was greatly affected by the organic matter content.There was a strong negative correlation between the relative abundance of the Lactobacillus in the Bacteroidetes and the organic matter content.