Recent experience and developments using the Biopur BAF process

Biological processes have been used to treat waste waters for many years in order to improve public health, remove offensive odours and to reduce pollution in the receiving watercourse. In the 1980's public concern led to UK and European legislation to further improve the treatment required of sewage prior to passing to a watercourse. This legislation is now embodied in the UK Bathing Water Directive and the Urban Waste Water Treatment Directive. This has lead to the improvement of sewerage and the reduction of the number of sewage discharges, as more sewers are now being fed to sewage treatment works. Sewage works have therefore often become overloaded and now require to be upgraded in order to meet these legislative requirements. In some cases completely new sewage treatment works have been required. Development of sewage treatment works is often in already built up areas where land can be often restricted. This combination of a sizeable market with technical constraints such as available land, odour control requirements and noise restriction has encouraged major innovation and development of sewage treatment processes to provide cost effective solutions using new technology. One such innovative process is the Biological Aerated Filter (BAF) of which many systems are now available on the market and well over 100 plants are currently operated worldwide, treating both industrial and domestic waste water for carbonaceous pollutant, ammonia or complete nitrogen removal. One innovative system that is now proving popular for treating wastewaters is the Sulzer Biopur biological aerated filter. This uses a submerged structured packing rather than the more common granular forms, which leads to a number of advantages for operating companies. This paper presents a brief description of the Biopur BAF process, its key operating features, and three case studies using the Biopur process for wastewater treatment in the UK.