Vertical Shaft Bioreactors.

The Vertical Shaft Bioreactor (VSB) treatment system is essentially a high rate activated sludge process capable of operating at food to microorganism ratios (F/M) of between 0.5 and 2.0 kg BOD₅/kg MLVSS/d. These extremely high loadings are achievable because of the capability of the system to carry and maintain mixed liquor volatile suspended solids (MLVSS) concentration values between 5.000 and 10,000 mg/L. As a result, a much lower volume (aeration period) is required than in the conventional activated sludge process. The process consists of a vertical subsurface reactor shaft 0.75 to 6 m in diameter and 75 to 125 m deep, with hydraulic mean residence times in the order of 60 min. The following aspects of the VSB process are covered: Process description, technical development, vertical bioreactor system and its variations, process theory and design basis, process design, operation, and maintenance, comparison with equivalent technologies, and case studies. [ABSTRACT FROM AUTHOR]