Using Covered Anaerobic Ponds to Treat Abattoir Wastewater, Reduce Greenhouse Gases and Generate Bio Energy
Wastewater treatment ponds are the preferred method for treating rural municipal wastewater and agricultural wastewater in Australia due to their simplicity to build and operate (Laginestra and van-Oorschot 2009). Pond design consists of a series of facultative and polishing ponds, with the inclusion of a primary treatment anaerobic pond for wastewater with high solids content. The pond surface area required for treatment can be reduced if physical and/or mechanical methods such as baffles, recirculation and subsurface mixing are used to manage the sludge.
Wastewater from meat processing plants has a high influent Biochemical Oxygen Demand (BOD) of around 2,000 mg/L, requiring treatment in an anaerobic pond prior to stabilisation in facultative and aerobic ponds in series (Green 1992). A typical meatworks effluent analysis includes a high total solids content, and a high total fat content (Husband 1992, Table 1.1). Screens and/or dissolved air flotation systems are often used as a primary pre-treatment in meat processing plants to remove fat and solids that might otherwise overload wastewater treatment ponds. In contrast to many other wastewater treatment influents, the temperature of wastewater from abattoirs is high, of the order of 35 to 37°C. This can be an advantage for anaerobic
treatment, as biogas production rates increase with temperature (Chynoweth et al 1998).