Over the past few decades the biological efforts were generally based on two distinct principles of suspended growth selleck compound and attached growth routes [6].The conventional activated sludge process is a suspended growth technology comprising of an enrichment culture of microbial consortia in order to remove impurities and transform wastewater into environmentally acceptable quality [7]. In this system the culture is retained to maintain convenient sludge age and treatment reaction rates. The microorganisms absorb organic material to grow and form the flocs of biomass [8, 9]. However, the attached growth systems are advanced to the suspended biomass processes. Attached growth creates the biofilm on the support media to provide a better treatment efficiency due to accumulation of high microbial population in the presence of large surface area [10, 11].
The shape and size of biomass-supporting media can also play a significant role in the design of biofilm processes in order to meet an obligatory surface area for microbial growth [12]. The microorganisms secrete a sort of natural polymer to facilitate firm adhesion on inert support matrix for biofilm development and biooxidation mechanism [13, 14]. Numerous investigations have demonstrated the efficiency of the attached growth unit processes in wastewater treatment, although the key advantage of these practices is rarely exploited in full-scale processes due to oxygen transfer limitations into thick biofilms [15].
In that order, the packed-bed biofilm technologies have high specific surface area and fixed biomass concentration leading to a smaller volume of reactor, while biofiltration techniques may cause choking and clogging dilemma [16, 17]. Likewise, the moving-bed biofilm reactor is incorporated with the advantage of conventional activated sludge and fixed-film practices [11, 18]. Thus, it is significantly important for overcoming some of the apparent limitations and evaluate the performance of biological systems where the most suitable technologies are available for on-site residential wastewater treatment. The comparative research also could lead to knowledge sharing of appropriate selection and operation of treatment techniques, particularly in developing countries [19].
The present scientific approach is an attempt to compare and review the potential future use of three aerobic biological systems, namely, conventional activated sludge process (CASP), moving bed biofilm reactor (MBBR), and packed-bed biofilm reactor (PBBR) for on-site treatment of wastewater from residential Drug_discovery complexes. The packed-bed biofilm reactor is operated under a modified specific arrangement to improve the performance of the process, reduce the limitations of attached growth technologies, and create a particular air distribution pattern for possible oxygen penetration into thick biofilms.