Discharge toxic

The use of filtration to polish biological treatment system effluent has become more popular in recent years because of more stringent discharge requirements. The 1977 EPA survey of petroleum refineries indicated that 27 of 259 plants used filtration as part of the existing treatment scheme and 16 others planned to install filtration systems in the near future [5]. Filtration can improve effluent quality by removing oil, suspended solids, and associated BOD and COD, and carryover metals that have already been precipitated and flocculated. Improved effluent filtration in one recent instance helped a Colorado refinery to meet the newly adopted discharge toxicity requirements [49]. 

Figure 1. Evolution of effluent toxicity in France from 1974 to 1993 in terms of actual (discharged toxic units) and avoided (treated toxic units) toxic loading reaching surface waters.

It is also felt that some applications, even if to a limited extent, just are around the corner. Among them probably are corrosion-stable electrodes, like DSA, for the preparative electrolysis, microelectrodes for sensors and the electroanalytical purposes and electrode arrays for discharging toxic contaminants, among others. 

Vent into local exhaust devices any apparatus that may discharge toxic vapors, fumes, mists, dusts, or gases. Never release toxic chemicals into cold rooms or warm rooms that have recirculating atmospheres. 

In the chlorine disinfection, reducing agents like sulfur dioxide must be used to eliminate the discharged toxic chlorine. Besides, special considerations must be applied to control natural organic matter (NOM) in water source or to reduce the potential by-product precursors after the disinfection unit. These concerns however become less obvious when UV radiation is used for disinfection of water. 

Pressure-relief devices that may discharge toxic, corrosive, flammahle, or otherwise hazardous or noxious materials should he vented in a safe and environmentally acceptable mannCT such as scrubbing and/ or diluting with nonflammable streams. 

Avoidance of "routine" exposure Develop and encourage safe habits (23) avoid unnecessary exposure to chemicals by any route (23). Do not smeU or taste chemicals (32). Vent apparatus which may discharge toxic chemicals (vacuum pumps, distillation columns, etc.) into local exhaust devices (199). Inspect gloves (157) and test glove boxes (208) before use. Do not allow release of toxic substances in cold rooms and warm rooms, since these have contained recirculated atmospheres (209). 

Wallis, P., Gehr, R. Anderson, P. (1996) Fluorides in wastewater discharges toxic challenges to the St. Lawrence river biological community. Water Quality Research Journal of Canada, 31, 809-838. 

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