|
With the improvement of urban sewage treatment capacity, sludge disposal on the development of urban construction and environmental protection has great significance. Sludge maked soil amendments was an effective way to achieve resources. In this paper, the static positions composting test device was used for sewage sludge treatment after strengthening infiltration in Zheng Runzhou waste water treatment plant of Zhenjiang city. We investigated the effect of soil conditioner mixed earthworm and straw, and analysised the sludge content of each component of the relationship between indicators, and undertook a comprehensive evaluation about the soil amendments . The principal conclusions were obtained as follows.①During the 80-days of biological drying in the natural state, the moisture content of the whole composting piles had a smaller rate of change because of the low ambient temperature. The product of the biological drying moisture dropped to 55%. Less nitrogen losed. The rate of TN loss in three compost piles were 34.57 %,10.24%and 25.40%, respectively. The rate of TP loss in three compost piles were 76.81%,76.88% and 76.34% respectively. To the end of composting, C/N ratio of three compost piles were stable from 14.54,20.26,20.44 to 12.74,8.55,9.94 respectively. Seed germination index in three compost piles were 88±3%, which could meet the relevant standards of compost.②During the composting tests in the natural state, the whole composting piles of high temperature was short. The nitrogen loss was less and the rate of TN loss in three compost piles were 17.4 %,16.0%and 16.8%, respectively. When the pile temperature is less than 32°C ,ammonium started into nitrate and the percent conversion were 44.4%,41.9%,35.9% respectively. The total phosphorus content were stable in 32.6,31.6,32.6g.kg-1 respectively. The available phosphorus content increased from 482.8,387.9,476.2 mg.kg-1 to 616.3,620.6,674.1 mg.kg-1 after the end of compost. The rate of the available phosphorus increase in three compost piles were 27.7 %,60.0% and 41.5%, respectively.Seed germination index in three compost piles were 90±3%, which could meet the "municipal wastewater treatment plant emission standards" （GB18948-2002）.③After two treaments of earthworms, straw and strengthening infiltration of sewage sludge composting, part types of heavy metals in the soil conditioner in a certain degree of enrichment except mercury, chromium, arsenic. Other types of heavy metals in the soil conditioner had a certain degree of enrichment, but did not exceed the national standard Limits. Compared the reactor piles adding earthworms to the reactor pile whithout earthworms, the heavy metal content was decreased. It indicated that earthworms could effectively reduce the concentration of heavy metals in the pile. The products of heavy metal concentrations was below the "municipal wastewater treatment plant emission standards" （GB18948-2002）. Hence,the product provided the the use conditions of landscaping and sandy soil improvement.④The composting method may meet the sludge processing requirements in Zheng Runzhou waste water treatment plant. Through the sludge mixed with earthworm and straw in natural composting, the earthworms stocking density was 5.6kg/m3, and the mass ratio of sewage sludge and straw was 12.5:1. This treatment could maintained a hige content of nitrogen and phosphorus, and was the maximum utilization of sludge retained its original value. Hence it was an efficient, eco-friendly way of sludge treatment.
|