A model for the simulation of nitrification in activated sludge is presented and calculations are compared with experimental results from different sources. The role of protozoa and the influence of reactor type and of diurnal variations in flow and strength of the sewage are considered. Favorable conditions for nitrification are low rates of sludge wasting, high temperatures, plug-flow-type re...

This review describes the historical development and current state of metals leaching and sulfide mineral biooxidation by the minerals industries. During the past 20 years commercial processes employing microorganisms for mineral recovery have progressed from rather uncontrolled copper dump leaching to mineral oxidation and leaching in designed bioheaps for oxidation of refractory gold ores and...

Spray aeration is a comparatively low-cost option to reduce trihalomethane (THM) concentrations in distribution system storage. The effect of spray on unregulated, toxic disinfection by-products was investigated bench-scale apparatus closed-tank and open-tank experiments. In the experiments, initially over 90% THMs, trichloroacetonitrile, chloropicrin were removed, while 36% dihaloacetonitriles...

In order to accurately evaluate the comprehensive operation efficiency of aerobic biological treatment system in wastewater plants (WWTPs), process state aeration performance tester and specific oxygen uptake rate online monitoring device were used measure oxygenation activated sludge tank, tank was evaluated by combining physical-chemical indexes water quality analysis system. The results show...

In this study, the optimization of different process variables-pH (4-6), aeration rate (200-550 rpm) and agitation rate (0.6-1.8 vvm) were investigated using rotating simplex method and uniform design method to enhance xylitol production from xylose by D. nepalensis in a batch stirred tank bioreactor. Maximum xylitol productivity (0.576 g L-1 h-1) was obtained at pH 4.0, agitation 300 rpm and a...