Sewage works final effluent

There is little information available on standards for lead in sewage works effluent. This may be due to low concentrations of lead normally found in treated effluent (Section 6.4.2) which are unlikely to cause the freshwater standards previously cited to be exceeded (Section 6.2.2), given a reasonable dilution of the effluent by the receiving water. 

The Los Angeles District which administers the area s Joint Water Pollution Control Plant which discharges to the sea, has set an effluent requirement for lead of 0.1 mg dm [9]. They propose to raise tliis, however, to 0.4 mg dm , based on a 50 1 dilution at the ocean outfall not previously allowed for. 

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Table 3.10 Concentrations of lead in sewage and final effluent of the Oxford Sewage Treatment Works, 24 h values, [6].

Laxen, D.RH. and Harrison, R.M. (1981) The physico-chemical speciation ofCd, Pb, Cu, Fe and Mn in the final effluent of a sewage treatment works and its impact on speciation in the receiving river. Water Res., 15, 1053-1056. 

Lead concentrations typical of those found in raw and treated sewage effluent are indicated by the data for the Oxford Sewage Treatment Works (Table 3.10) [6]. Tlie concentrations are highly variable, especially in the final effluent. In this particular case, the final effluent concentrations are only just above background levels in the receiving water. 

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