ANALYSIS ON CONTENT CHARACTERISTICS OF NUTRIENTS AND HEAVY METALS IN URBAN SLUDGE OF SHAANXI PROVINCE

The content characteristics of TN, TP, TK and OM, as well as 6 kinds of heavy metals including Cr, Cu, Ni, Pb, Zn, As in the sludge of 32 urban sewage treatment plants in different areas of Shaanxi province were investigated in different water periods. The results indicated that:1) The contents of N, P nutrients and OM in urban sludge in Shaanxi province were abundant, but TK content was not high. The distribution characteristics of the total nutrient content of sludge generally showed the sequence of low water period>flat water period>abundant water period, in which TN and OM contents were very significantly affected by the water period (P_J-T<0.001), while TP and TK contents were not significantly affected by the water period (P_J-T>0.05). 2) The distribution of heavy metal contents in urban sludge of Shaanxi province showed log-normal. The contents sequence of 6 kinds of heavy metals were Zn>Cu>Cr>Pb>Ni>As. There was no significant difference in heavy metals contents of sludge in different water periods (P_ANOVA>0.05). 3) The urban sludge in Shaanxi province had a high agricultural value and the heavy metal contents in urban sludge in Shaanxi province were generally at a relatively lower level; the sludge was suitable for application in forest land, pasture grassland and cultivated land without growing edible crops; land modification for medium alkaline soil. Meanwhile, special attention should be paid to As content in the sludge.