Investigating the Performance of Moving Bed Biofilm Reactor (MBBR) on Treatment of Petrochemical Waste Water for Phenol Removal

【摘要】：The various sources of phenol, adverse effects, human and animal exposure limits reflects the increased environmental concern for its control and eradication in water bodies. This is especially so in view of the fact that it is the rudimental material (basic organic constituent) in the petrochemical industry an industry recognized globally to consist of a complex combination of interdependent operations concerned with separation of crude molecules constituents, molecular cracking, molecular rebuilding and solvent finishing all of which ends up discharging a complex array of solids and fluid streams, Placing in cognizance, the environmental presence of phenol, the relative abundance in the environment and its vulnerability, it will be merely stating the obvious to say they are a menace and perhaps even a catastrophe due to their numerous adverse effects. These effects were highlighted while investigations on phenol removals under dual conditions of low and ambient temperatures were studied. This report mentions also the origin, effect, and characteristics of phenol. It describes also the conventional methods employed for treating phenolic waste waters, such as the activated sludge process being the foundation for most biological processes, Sequencing batch reactors, electrochemical oxidation, photo catalytic oxidation.it went further on highlighting of biofilm processes focusing on the MBBR technology a refinement of the activated sludge process, identified as a dynamic compact and cost effective technique within the biological methods because of its excellent traits. Highlights were also made on the various biofilm processes employed in treating phenolic waste waters. During the course of this investigations various concentration of phenol were explored under dual conditions. Under psychrophilic conditions an initial phenol range of 100-500mg/l was studied at 24 hours HRT utilizing phenol and sugar as sole carbon source for the feed waste water following a simultaneous step wise increase and decrease in phenol concentration at a fixed 1200mg/l COD concentration. Indications reflect a maximum removal efficiencies of approx.100% and over 95% for phenol and COD at the peak concentrations of 400mg/l and 500mg/l and minimum removal efficiencies of over 56% and 64% for phenol and COD respectively at 300mg/l phenol concentrations. Thereafter a 600mg/l-1200mg/l phenol concentration was embarked upon with phenol as sole carbon source of waste water at 24 hours HRT. Good removal efficiencies were obtained for both COD phenol with peak removal of 86% and 89% for COD and phenol respectively at 1200mg/l concentration. A phenol concentration of 1200mg/l was focused on being in the range typical of petrochemical waste waters while the effects of HRT and concentration on phenol removal were investigated. A 30 hours HRT was realized as being optimal. Indications are that there are a higher abundance of nitrifying bacteria and limited proportion of anammox bacteria in the reactor; this was done in a bid to ascertain the fact or not of anammox bacteria in the reactor. Experimental outcomes under mesophillic trials indicated over 99% COD removal efficiencies for 1500mg/l phenol concentrations and about 87% for 2500mg/l concentration. The influence of sulphide on phenol removal at a 22mg/l concentration studied indicated that a prolonged HRT is imperative for optimal removal.