This standard stipulates the control standards for the pollutants (e.g., Cadmium, Mercury, Aluminum, Chromium, Arsenic, Boron, Cooper, Zinc, Nickel, mineral oil, and benzopyrene) in sludge for agricultural use, including the sludge from urban sewage treatment plants, sludge from sedimentation tank, sludge produced by some organisms and the sedimentation sludge of rivers, lakes, reservoirs, pools, dykes and trenches. For example, for acid soils with pH value <6.5, the maximum allowable content is 5mg/kg dry sludge; and for neutral and alkali soils with pH value ≥6.5, the maximum allowable content is 20mg/kg dry sludge. The standard also stipulates a maximum amount of sludge applied annually for agricultural use (not more than 2000kg, calculated at 2000kg) as well as the fixed number of year for application, and the monitoring approaches.

Control standards for pollutants in sludges from agricultural use (GB 4284-84)