贵州省典型城市污水处理厂污泥养分与重金属含量调查

Major Nutrients and Heavy Metals of Municipal Sewage Sludge in Guizhou Province

分别采集贵州省8个典型地级城市污水处理厂冬季和夏季的脱水污泥样品,进行室内分析测试,研究其养分和重金属特性。结果表明,贵州省主要地级城市脱水污泥pH为6.5-7.4,盐分含量为0.4-0.9。城市污泥中有机质、全量N、P高于一般农家肥,但全K量较低。污泥中全量重金属Cu、Pb、Ni、Cr、Hg和As均远低于国家农用标准,但一个处理厂污泥Cd、Zn超标,另有一处理厂污泥Cd超标,有3个处理厂污泥存在Zn超标现象。形态分析表明,Cd在多数污泥中化学形态主要是以生物有效态的形式存在,而Zn主要以稳定的化学形态存在,说明Cd存在环境风险,而Zn相对安全,表明贵州地区脱水污泥多数可安全农用,冬季和夏季脱水污泥的养分和重金属浓度没有显著差异。

Sewage sludge samples were collected from eight cities in Guizhou Province in winter and summer and the pH,salinity,content of nutrients and heavy metal concentrations were then determined.Results showed that pH of these municipal sewage sludges ranged from about 6.5～7.4 and the salinity from 0.4%～0.9%.The organic matter,total N and P contents were higher than for common farmyard manure but the K concentration was relatively lower.The total concentrations of Cu,Pb,Ni,Cr,Hg and As were much lower than the states standard for sludges for agricultural purpose;Cd and Zn concentrations together exceeded the standard in only one sample,Cd concentration alone exceeded the standard in another sample,and Zn concentration exceeded the standard in three samples.This Zn exists mainly in a stable chemical form,and the Cd mainly as bioavailable Cd and suggesting a potential environmental Cd risk but the relative safety of the sludge Zn.No significant difference was found between sludge samples collected in winter or summer seasons.Most on the municipal sludges from Guizhou Province were deemed safe for agricultural use with only a few posing any potential risk.