The Study And Application On The Large-scale Production Of Sludge Organic Fertilizer

As population and sewage treatment rate increases, the number of sewage sludge also grows,sludge disposal has become one of the biggest environmental problems in the large and medium cities.The garden area increases in recent years,the demand for the fertilizer is increasing year by year,the urban sludge nutrient has the natural advantage in the preparation of garden green manure.This study intends to study the basic properties of sixth, fifth, eighth, tenth sewage treatment plant’s sludge, sludge compost, the planting test of Chinese Cabbage and garden plants,in order to find an effective and economic way of sludge disposal in Xi’an City.The test results show that:(1)The water content average value of four sewage treatment plant in Xi’an is 77.83%.The average value of EC is 2.67 m S/cm,is higher an order of magnitude than that of soil, the p H average value is moderate, is 8.54;The nutrient content of four sewage treatment plant is in line with national standards of agricultural organic fertilizer, the fertilizer efficiency is the same as traditional organic fertilizer;In addition to the contents of heavy metals in eight plants, others are in line with national standards of landscaping,but is not in line with national standards of the organic fertilizer.It should be treated for harmless.(2)In the composting experiment,set sludge:tobacco stems(volume ratio)=1:1, sludge:tobacco stems=2:1(volume ratio),sludge:cow dung:tobacco stems(volume ratio)=1:1:1 respectively,after composting,the moisture content, p H and organic matter are in lin e with national standards of organic fertilizer;total nutrient content were 6.42%,6.47% and 5.39%,more than the nutrient criteria of Chinese organic fertilizer GB;heavy metal content is decreased in different degree;considering the physical and chemical properti es,fertilizer and the content of heavy metals,the compost effect of sludge:cow dung:tob acco stems(volume ratio) = 1:1:1 is significantly better than other treatments.(3)In Chinese Cabbage planting experiment,when the amount of fertilizer is less than 5%,the height and fresh weight of cabbage plant increases with the increasing of the amount of fertilizer,when the amount of fertilizer is more than 5%,the height and fresh weight of cabbage plant decreases with the increasing of the amount of fertilizer,when the amount of fertilizer is 40%,the growth is inhibited.The content of Cd and Pb are less than the national food safety standards,when the amount of fertilizer is less than 5%,the content of Cr is less than the standard,when the amount of fertilizer is more than 5%,it more than the standard;after planting,the content of Cu,Zn,Pb,Cd,Cr in soil increases with the increasing of the amount of fertilizer and it reaches the maximum when the amount of fertilizer was 40% are 33.41mg·kg-1、194.55 mg·kg-1、20.56 mg·kg-1、0.55mg·kg-1、40.74 mg·kg-1.(4)In the garden planting experiment,when the amount of fertilizer is 2.5kg/tree,th e plant height,basal diameter and crown width of Red Mansions are 172.33 cm,2.70 cm,71.53 cm,and 1.77%,21.62%,1.88% higher than the CK;when the amount of fertilizer is 1kg/tree,the plant height,basal diameter and crown width of Atropurpurea are 331.33 cm,2.23 cm,99.40 cm,and 7.69%,2.76%,7.70% higher than the CK;In the 0kg/tree~3kg/tree rang e of fertilizer,the plant height,base diameter, crown diameter of Li Tao increases along with the increase of fertilization amount.