Pollutant trading: estimating costs of phosphorus removal in wastewater treatment facilities
Beck, M. B.
Cummings, R. G.
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Current interest in developing schemes of pollutant trading as a market-based approach to achieving the goals of the Total Maximum Daily Load (TMDL) approach to watershed management is considerable. In this paper, our specific concern is the prospect of lowering nutrient levels in rivers and lakes using an offset banking scheme for pollutant trading between point and nonpoint sources of pollution. A basic pre-requisite for any such scheme is a good understanding of the costs of constructing entirely new (point-source) wastewater treatment facilities, or upgrading existing facilities, in particular in Georgia, in order to reduce the discharge of phosphorus to streams and rivers. In most situations, we need to adapt the already existing facilities — operating at a level of x % removal of P, say — to a higher level of y % removal. An approach based on extensive simulation studies is reported in the paper. Simulation has an important advantage over pilot-scale experiments, since the influence of a very wide range of design features and operating conditions can be rapidly evaluated on a consistent basis. To be specific, our studies have been based on the WEST simulation platform (Hemmis,nv, Kortrijk, Belgium).The results indicate that activated sludge process with alum addition is more economical then A/O and A/A/O process under the effluent TP limit of 2 mg/l.