Determination of Kinetic Constants of an Anaerobic Hybrid Reactor (AHR) Treating the Dairy Wastewater

摘要

The increased use of milk and milk products in India, the annual milk production rate crossed more than 121 million tonne. The dairy industry consumes large quantity of water for the various purpose of the works, namely milk processing, washing of containers and floors, etc. Though the dairy wastewater is biodegradable, it is very strong in nature. Hence in the present study, an attempt has been made to treat the complex diary wastewater by anaerobic hybrid reactor (AHR) which offers the advantages of upfiow anaerobic sludge blanket reactor (UASBR) and upfiow anaerobic filter reactor (UAFR) and to determine the biokinetic coefficients for the reactor from the experimental results obtained. The treatment of dairy wastewater was carried out by using a lab-scale anaerobic hybrid reactor (AHR) of 4.0 L volume and was operated at room temperature with an intermittent agitation for 15 min @100 RPM for once in every 4 hr. The inert media used in the reactor was poly propylene media (PP) which is cylindrical in shape and the density, specific area of the media were 0.9 and 320 m2/m3, respectively. The reactor was fed in an upfiow mode with low-strength dairy wastewater with concentrations of about 2.5-3.3 g COD/L.d. After 180 day of operation of the reactor and from the experimental results it was found that the. dairy wastewater could be effectively treated in the AHR with a maximum OLR of 6.53 kg/ L.d. and with the HRT of 0.42 day without clogging to the treatment efficiency of 85%. The polypropylene inert medias in the filter region of AHR were highly helpful in retaining the biomass inside the reactor and hence improved the performance of the reactor with increased solids retention time CSRT). In order to understand the behaviour of the AHR and to determine the kinetic constants, different mathematical models were applied. From the reactor performance the Grau second order model and the Stover Kincannon model, gave higher correlation values and hence found to be the most appropriate models for anaerobic hybrid reactor design. The Grau second order substrate removal constant (K_2) was found to be 6.79 per day for the overall anaerobic hybrid reactor (AHR) and by applying the modified Stover Kincannon model to the filter region of the reactor, the maximum removal rate constant (U_(max)) and saturation value constant (K_B) were found to be 166.67 g/L/d day and 175.17g/L/dTrespectively.