Surface water pollution control by appropriate effluent taxation : the Thachin river basin study, Thailand

Abstract

The Thachin River was ranked as the most polluted river in Thailand. Pig farms, Urban communities, Aqua cultures, and Industries were significant contributors to deteriorating water quality in Thachin River basin. Consequently, it is facing a serious problem of surface water quality especially when dealing with an accumulation of upstream wastewater discharges. It would be more appropriate, if the taxation model would take into account both the amount of pollution emission at the ‘end-of-pipe’ and the amount of wastewater contaminant in the surface water which should not exceed the environmental loading or overload the carrying capacity of the river ecosystem. This research purposed to seek the appropriated effluent tax system and constructed the optimization mathematical decision making model in order to make the maximization profit that met the environmental constraint and economic constraint from Thachin River. Moreover the amount of pollution discharges would not excess Total Maximum Daily Loading of Thachin River. The steps in estimating of appropriated effluent taxation were divided into 3 phases, Phase I, The data collection was divided into 2 aspects which were Environmental aspect and Economic aspect. First Environmental aspect was the actual information which concerned on pollution characteristic, carrying capacity, Total Maximum Daily BOD Loading, and Target of emission reduction of Thachin River. Second Economic aspect concerned on the production cost, abatement cost and the revenue of every activity in Thachin sub-basin. Phase II was the calculation of marginal abatement cost (MAC) of each main point source and the emission tax rate under Command and Control (CAC). Phase III was the construction of Mathematical Decision-making model and simulated by using optimization model for arriving the appropriate tax charge. The result showed that abatement cost of Uniform tax was lower than Non-uniform tax approximately of 3,480,944,681.53 Baht/year. Moreover the total expenses of Uniform tax was lower than Non-uniform tax approximately of 3,517,515,764.60 Baht/year which lead to the higher of net profit of Uniform tax approximately of 3,518,058,488.41 Baht. Both of Non-uniform and Uniform tax reduced efficiently the wastewater emission in Thachin River which met the standard requirement however, in term of economic, the Uniform tax was more efficient than Non-uniform tax because the total expense per revenue of entire river was lower than Non-uniform tax approximately of 0.552 %. The processes in this study are practical in applying of water pollution control in other rivers.