COMPARISONS OF AGRICULTURAL USING BETWEEN SEWAGE SLUDGE AND LIVESTOCK MANURE FOR NUTRIENT LOADING,ECOLOGICAL RISK AND POTENTIAL IN TAIYUAN METROPOLITAN AREA

摘要

The increase in nutrients (nitrogen,phosphorus and potassium) loadings from agriculture nonpoint source pollution has been one of the major sources of water pollution or eutrophication.Comparisons between sewage sludge and livestock manure for nutrients loading,ecological risk and agricultural using potential were investigated in Taiyuan metropolitan area of Shanxi to determine which one was more suitable for agricultural using in the studying area.The mean organic matter and nitrogen,phosphorus and potassium in sewage sludge were 350.12 g/kg,36.14 g/kg,21.50 g/kg and 12.00 g/kg,and the contents of organic matter and nutrients (N+P+K) all exceeded the specified values formulated by Disposal of Sludge from Municipal Wastewater Treatment Plant-Control Standards for Agricultural Use (CJ/T 309-2009).In contrast to livestock manure,sewage sludge had a comparable advantage for agricultural using due to the contents of organic matter and nutrients as well as the proportion ofN:P:K.The mean loadings of nitrogen,phosphorus and potassium can be ranked in the following decreasing orders as N>P>K for sewage sludge,and N>K>P for livestock manure,and all mean loadings of nitrogen,phosphorus and potassium did not exceed the ecological safety threshold values of 125 kg/ha*a,62.5 kg/ha*a and 62.5 kg/ha*a,which were published by the Ecological County,Ecological City and Ecological Province Construction Index (revised draft),besides the mean loading of phosphorus for sewage sludge.In particular,loadings of nitrogen and potassium were higher for livestock than sewage sludge,and loadings of phosphorus were higher for sewage sludge than livestock in different districts.According to the mean values of the monomial ecological risk index,nutrients can be ranked in the decreasing order of P>N>K for sewage sludge and K>N>P for livestock manure,and they were all below the safety threshold value of 0.5.In general,the ecological risks of nitrogen and potassium were higher for livestock manure than sewage sludge,and those of phosphorus were higher for sewage sludge than livestock manure.The mean potentials of agricultural using of sewage sludge and livestock manure were 1.07 t/ha*a and 4.59 t/ha*a respectively; livestock manure had higher potential than sewage sludge; and the restrictive factor were nitrogen and phosphorus for sewage sludge,nitrogen and potassium for livestock manure.In detail,the districts having negative potential were more for livestock manure using than sewage sludge using,furthermore,the negative potential for sewage sludge using was determined by phosphorus,and for livestock manure were all determined by potassium.Combining all the analysis with the local soil condition of low nitrogen,low phosphorus and high potassium,sewage sludge was more suitable for agricultural using than livestock manure in the ecological safety manner in the studying area.