MEMBRANE BIOREACTORS AND CONSTRUCTED WETLANDS FOR TREATMENT OF RENDERING PLANT WASTEWATER

The performance of a novel industrial membrane bioreactor (MBR) comprising denitrification, nitrification and ultrafiltration for the secondary treatment of primary treated animal rendering wastewater has been compared with an experimental, low-cost and novel vertical-flow constructed wetland planted with Typha latifolia L. (Reedmace or Broad-leaved Cattail). The process wastewater followed pre-treatment by dissolved air flotation (DAF). The mean DAF effluent gave highly variable chemical oxygen demand (COD) and ammonia concentrations of 5816 (standard deviation (SD): 3005.0) and 614 (SD: 268.7) mg/l, respectively. The mean MBR effluent for COD and ammonia was 37 and 86 mg/l, respectively. The mean treatment performance of the constructed wetland for COD, ammonia and suspended solids was 205, 67 and 57 mg/l, respectively.     

PRACTICAL METHODOLOGY FOR DETERMINING THE SIGNIFICANCE OF IMPACTS ON THE WATER ENVIRONMENT

There is currently limited guidance available in the UK for predicting the significance of the impacts of developments on the water environment. This may be partly due to the disparate nature of the components of the water environment, which are covered by a range of scientific and engineering disciplines. This paper reviews the current status of Environmental Impact Assessment for the water environment in the UK and identifies key methodologies and guidance. Proposals are made for a more detailed approach to determining the significance of impacts on rivers, stillwaters (lakes and ponds), groundwater and floodplains, building on methodologies previously developed for highways schemes. Account is taken of the Environment Agency's ongoing work to classify water features to meet the requirements of the Water Framework Directive.