Performance and process simulation of membrane bioreactor (MBR) treating petrochemical wastewater

Mathematical modelling of biological treatment is an effective tool to predict effluent quality. Model calibration is critical to improve the accuracy of simulation, which is normally carried out by fine-tuning the values of parameters according to the practical data. It indicated that huge amount of practical date will be consumed, and it cannot predict the treatment performance of new wastewater. In this study, the main objective was to investigate the feasibility of application BioWin software coupled with determination of sensitive parameters to predict the treatment performance of membrane biological reactors (MBRs) treating real petrochemical wastewater (PW). Model calibrations, i.e., COD fractions of petrochemical wastewater and kinetic parameters of biomass, were carried out using the respirometry method and the relationship between observed and true growth yield coefficients of the three lab-scale MBRs which were operated under different solid retention time (SRT). All the three MBRs had good organic and ammonium removal, with removal efficiencies higher than 80% and 99.9%, respectively. Simulation using the calibrated model also obtained good fit for effluent COD concentration, effluent nitrate concentration and bioreactor's MLSS concentration of all the three MBRs. The mean absolute percentage errors (MAPE) of the simulation mostly were lower than 22%. The results indicated that it is feasible to using BioWin, incorporated with appropriate determination methods of sensitive parameters, to simulate and monitor the treatment performance of MBR treating petrochemical wastewater. This is more time-saving and effective than fine-tuning values of all parameters. This study provides a valuable reference for simulation of industrial wastewater treatment using BioWin.

Identification and characterization of bilgewater emulsions

Literature on bilgewater focuses on empirically determined treatment methods and lacks specific information on emulsion characteristics. Therefore, this review discusses potential emulsion stabilization mechanisms that occur in bilgewater and evaluates common approaches to study their behavior. Current knowledge on emulsion formation, stabilization, and destabilization is outlined to provide researchers and bilgewater treatment operators with the knowledge needed to determine emulsion prevention and treatment strategies. Furthermore, a broad assessment of bilgewater emulsion characterization techniques, from general water quality analysis to advanced droplet stability characterization methods are discussed in detail. Lastly, a survey of typical bilgewater characteristics and information on standard synthetic bilgewater mixtures used in the testing of oil pollution abatement equipment are presented. Overall, the goal of this article is to provide a better understanding of physical and thermodynamic properties of emulsions to help improve bilgewater treatment and management.

PAH mineralization and bacterial organotolerance in surface sediments of the Charleston Harbor estuary

Semi-volatile organic compounds (SVOCs) in estuarine waters can adversely affect biota but watershed sources can be difficult to identify because these compounds are transient. Natural bacterial assemblages may respond to chronic, episodic exposure to SVOCs through selection of more organotolerant bacterial communities. We measured bacterial production, organotolerance and polycyclic aromatic hydrocarbon (PAH) mineralization in Charleston Harbor and compared surface sediment from stations near a known, permitted SVOC outfall (pulp mill effluent) to that from more pristine stations. Naphthalene additions inhibited an average of 77% of bacterial metabolism in sediments from the more pristine site (Wando River). Production in sediments nearest the outfall was only inhibited an average of 9% and in some cases, was actually stimulated. In general, the stations with the highest rates of bacterial production also were among those with the highest rates of PAH mineralization. This suggests that the capacity to mineralize PAH carbon is a common feature amongst the bacterial assemblage in these estuarine sediments and could account for an average of 5.6% of bacterial carbon demand (in terms of production) in the summer, 3.3% in the spring (April) and only 1.2% in winter (December).