Residual sludge from the small scale wastewater treatment plant is always a problem remained in biological wastewater treatment, it may cause secondary pollution if not disposed well.

Adoption of second version of generalized design of small scale urea plant issued by China Wuhuan chemical engineering Corp. in Ninyang fertilizer plant and minor modification on it are introduced.

The paper introduces the different kinds of zinc process, combining engineering, it also suggests the technical reform trends to small-scale zinc plant.