Effluent is an out flowing of water or gas from a natural body of water or from a human made structure .Effluent is defined by the United States Environment protection Agency as “wastewater, treated or untreated that flows out of treatment plant, sewer or industrial outfall. Generally refers to wastes discharged into surface waters”. The compact oxford English Dictionary defines effluent as “Liquid waste or sewage discharged into a river or the sea.
Waste water discharged from a textile wet processing plant contains various types of impurities depending on the types of dyes, chemicals, auxiliaries and process used. Some of these impurities are considered toxic while some are not. Off course the toxicity or harmless also depends on the amount present in a certain amount of wastewater. various countries have different standards for acceptable level of toxicity .For example water is used for drinking purposes, irrigation in the fields, in various types of textile, chemical, food processing ,leather processing and pharmaceutical industries, and also to maintain the aquatic life in the canals and rivers. In all these cases different level of purity in terms of toxicity and harmfulness is required. this is mainly intended for wastewater generated in the various textile wet processing industries. Therefore, the present discussion will mainly be concentrated on wastewater generated in various types textile processing industries. This is Bangladesh govt.standard .the level of toxicity was considered for water intended to be discharged into river or canals. the wastewater generated in a textile wet processing industry can be recycled back for consuming in the plant as raw influent or even can be used for drinking purposes but this is expensive enough. So wastewater as generally discharged into the river or canals.
Characteristics of waste water to discharged into the environment. (Recommended by the dept. of environment, Government of Bangladesh).
BOD <50 PPM or mg/.L
COD <200 PPM or mg/L
TSS <100 PPM or mg/L
TDS <2,500 PPM or mg/L
OIL & GREAS <10 PPM or mg/L
TEMPERATURE <300 C