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.     

HYDRAULICS, WATER QUALITY AND VEGETATION CHARACTERISTICS OF GROUNDWATER-FED OPEN DITCHES

A novel peatland management strategy to utilise the high nutrient-retention potential of degenerated peatlands has been implemented in Northern Germany. The effect of raised water levels and extensive land-use management on hydraulic properties, water quality and vegetation characteristics of heavily vegetated and groundwater-fed open ditches, was investigated at the River Elder Valley - a nationally important wetland case study. A better understanding of the effect of vegetation on the temporal flow patterns and the hydraulic retention times is of high scientific interest, especially for improving nutrient standards in lowland rivers. Within-ditch vegetation and other hydraulic obstructions, including accumulated silt and organic debris, increase the hydraulic retention time and lead to an improvement of the water quality along the open ditch. Lower parts of the open ditches were flooded by the River Elder, due to the absence of a mowing scheme during late summer     

STORMWATER QUALITY ASSOCIATED WITH A FULL SILT TRAP DISCHARGING INTO AN URBAN WATERCOURSE

The aim of this project was to assess the influence of a full silt trap on the quality of stormwater which was discharged into an urban watercourse. The average SS concentrations of the outflow were 2.0 and 34.1 mg/l during dry-weather and wet-weather conditions, respectively, and SS concentrations of up to 141.6 mg/l were recorded during storms. Treated stormwater SS concentrations were often high, compared with secondary sewage-treatment standards of ≤30 mg/l. Pollutants accumulated in the silt trap.     

Cost-Effective Integrated Drainage and Wastewater Management Systems

This paper presents an overview of the components of wastewater management systems with particular reference to the emerging 'pollution preventative'source-control system which accords more with 'nature's way'and sustainable-development principles. The types and characteristics of pollutants, and also the ease of the removal of pollutants from wastewaters and the aquatic environment, are discussed. The source-control system is compared with the traditional conventional system on the basis of technical, economic, socio-cultural and environmental appropriateness in order to aid integrated drainage and wastewater treatment system selection and decision making - particularly in developing countries.     

SUSTAINABLE OPERATION OF A SMALL-SCALE FLOOD-ATTENUATION WETLAND AND DRY POND SYSTEM

Pond structures as cost-effective source-control drainage techniques can be applied in order to reduce the downstream risk of flooding. In the UK, there are no widely accepted performance data on pond structures, yet there is a need for detailed design and operation guidelines, coupled with data on urban biodiversity enhancement, maintenance, reliability, economics and social acceptance. The purpose of this study was to investigate (a) cost-effectiveness and self-sustainability of stormwater pond systems, and (b) compatibility with the primary needs of water removal and storage to wildlife and amenity enhancement. A case study was used, based upon a combined attenuation wetland and dry pond construction for roof-water runoff.