Many industries produce wastewater more or less. Today, with increasingly stringent environmental requirements and anincreasing shortage of water resources, these wastewaters mustbe treated to be discharged or recycled. According to incompletestatistics, these industrial sectors that produce sewage include. mining (coal, phosphate, aluminum, iron, potash, copper, goldborax, etc.), oil extraction, steel, paper, food processing (dairyproducts, meat).Class, starch, sugar, wine, potato processingetc.), refining, machinery manufacturing and repair, chemi calelectroplating, pharmaceutical, ceramics, printing and dyeingelectricity, leather and so on.

Industrial wastewater containing organic matter is usuallytreated by biological methods, in which case flocculants areused to aid sludge dewatering.

When the industrial wastewater is treated by physical chemistry. the coagulant and/or focculant is used to promote thesedimentation of suspended impurities in the water. Flocculantsare sometimes used to help sludge dewatering.

Due to the variety of sources, chemical components, andimpurities in industrial wastewater, coagulants/focculants that treat them often tend to be different. Therefore, for a certain kind of industrial wastewater, the coagulant and flocculant should bescreened first in the laboratory. However, based on practica! experience, there are still some general rules for reference when selecting flocculants.

TYPES OF SLUDGE		NONIONIC FLOCCULANT	ANIONIC FLOCCULANT	CATIONIC FLOCCULANT
AGRICULTURAL AND SIDELINE FOOD	SLUDGE DEWATERING	√		√
	WASTEWATER TREATMENT
DYEING	SLUDGE DEWATERING			√
	WASTEWATER TREATMENT		√
PAPERMAKING	SLUDGE DEWATERING		√	√
	WASTEWATER TREATMENT		√	√
CHEMICAL ENGINEERING	SLUDGE DEWATERING	√	√	√
	WASTEWATER TREATMENT		√	√
MECHANICAL PROCESSING	SLUDGE DEWATERING	√	√	√
	WASTEWATER TREATMENT	√
	OIL-CONTAINING WASTEWATER TRAETMENT			√