Development of inert media for the design of anaerobic hybrid reactor (AHR) for treating industrial wastewater

Abstract

The present research sought to find out ways to overcome some shortcomings of the high rate anaerobic reactors which rely upon the cell immobilization techniques, to improve the Solids Retention Time (SRT) and thereby to shorten the Hydraulic Retention Time (HRT). The most popular high rate anaerobic reactors are the Upflow Anaerobic Sludge Blanket Reactor (UASBR) and the Upflow Anaerobic Filter Reactor (UAFR). However, both designs suffer from some of the operational difficulties such as clogging, channeling, and poor or no granulation etc., to combine the advantages of UASBR and UAFR in a single reactor, a new reactor was developed, namely the Anaerobic Hybrid Reactor (AHR), which has a filter bed at the top and a sludge blanket at the bottom. The performance of AHR can be enhanced by developing a suitable inert medim, which gets coated with or will trap biomass and thereby prevent the wash out of biomass at the outlet of the reactor and thus ensure a longer SRT. In the present research work an effort has been made (i) to find out the optimum operational conditions of the reactor (ii) to study the material influence of the inert media (iii) to study the influence of physical characteristics of the inert media for the better performance of the AHR using dairy wastewater as substrate and thereby to select the best inert media and (iv) to use the same in the AHR for treating different industrial wastewaters. To ascertain the optimum operating conditions of the reactor, three laboratory scales AHRs were operated in three distinct conditions, such as without agitation (AHR11), intermittent agitation for 15 minutes for every four hours at the rate of 100rpm (AHR12) and continuous agitation at the rate of 100rpm (AHR13) using 30/35mm diameter and 29mm height cylindrical polypropylene inert media and dairy wastewater as substrate. As the result of this empirical study, out of three reactors, AHR12, AHR13 performed better with respect to a threshold 80% COD removal efficiency and biomass activity.