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GE power station wastewater treatment

Challenge

Coal-fired power plants needed a cost-effective, low-maintenance solution capable of consistently producing treated water that meets regulatory standards.

Problem

Many coal-fired power plants employ flue-gas desulphurisation (FGD) using dedicated scrubbing systems to remove contaminants such as sulphur dioxide from boiler exhaust gases generated by burning coal. This method reduces air pollutant emissions but requires the removal of selenium and other metals from the wastewater. Currently this is achieved by constructing wetlands – however this uses large amounts of land and is not particularly effective.

Solution

GE developed ABMet (Advanced Biological Metals Removal Process) which, after removing gross solids, removes selenium, arsenic and mercury to acceptable concentrations. The technology can be applied to lowering harmful levels of nitrate, selenium and other heavy metals found in wastewater streams from power plants, mines and agricultural sites. The simple, low-energy system uses beds of granular activated carbon, inoculated with selected strains of naturally occurring, non-toxic and non-pathogenic micro-organisms, to produce treated water that exceeds the world's most stringent regulatory standards for selenium removal.

Benefits

Reduces the concentration of selenium in coal power plant flue gas desulphurisation blow-down by up to 1,000-fold
Treated water contains even less selenium than allowed under some of the world’s toughest drinking water standards
Compared to nanofiltration systems it requires 79% less energy to operate and saves enough energy to power 21 homes
Compared to ferrous-iron systems it requires fewer chemicals and saves more than 77% in chemical costs per year
Compared to wetlands treatment systems it uses 90% less land area and reduces the amount of water-borne selenium discharged into the environment

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