Anaerobic-Filter Pretreatment Kinetics

Pilot studies with synthetic and actual dairy wastewater showed that anaerobic-filter pretreatment at ambient temperature (20-24°C) was capable of reducing total BOD₅ by up to 96%. Analysis of the reactor kinetics showed that the reactions were complete in about two days detention time, which corresponded to a volumetric loading of 1.7 kg COD/m³-day. Because of declining marginal removals with increased detention time, simple kinetic expressions were not appropriate representations of the reactor performance. Fermentative reactions dominated during the first 0.75 days of treatment, while methanogenic reactions dominated thereafter. Although effluent quality deteriorated, the anaerobic filters could handle a severe shock load as long as sufficient alkalinity had been added to keep the pH above 6.8 throughout the reactor.