Abdul Wahab Mohammad

Pollution control technologies for the treatment of palm oil mill effluent (POME) through end-of-pipe processes

Palm oil production is one of the major industries in Malaysia and this country ranks one of the largest productions in the world. In Malaysia, the total production of crude palm oil in 2008 was 17,734,441 tonnes. However, the production of this amount of crude palm oil results in even larger amounts of palm oil mill effluent (POME). In the year 2008 alone, at least 44 million tonnes of POME was generated in Malaysia. Currently, the ponding system is the most common treatment method for POME but other processes such as aerobic and anaerobic digestion, physicochemical treatment and membrane filtration may also provide the palm oil industries with possible insights into the improvement of POME treatment processes. Generally, open ponding offers low capital and operating costs but this conventional method is becoming less attractive because the methane produced is wasted to the atmosphere and the system can not be certified for Carbon Emission Reduction trading. On the other hand, anaerobic digestion of POME provides the fastest payback of investment because the treatment enables biogas recovery for heat generation and treated effluent for land application. Lastly, it is proposed herewith that wastewater management based on the promotion of cleaner production and environmentally sound biotechnologies should be prioritized and included as a part of the POME management in Malaysia for attaining sustainable development. This paper thus discusses and compares state-of-the-art POME treatment methods as well as their individual performances.

A holistic approach to managing palm oil mill effluent (POME): biotechnological advances in the sustainable reuse of POME.

During the last century, a great deal of research and development as well as applications has been devoted to waste. These include waste minimization and treatment, the environmental assessment of waste, minimization of environmental impact, life cycle assessment and others. The major reason for such huge efforts is that waste generation constitutes one of the major environmental problems where production industries are concerned. Until now, an increasing pressure has been put on finding methods of reusing waste, for instance through cleaner production, thus mirroring rapid changes in environmental policies. The palm oil industry is one of the leading industries in Malaysia with a yearly production of more than 13 million tons of crude palm oil and plantations covering 11% of the Malaysian land area. However, the production of such amounts of crude palm oil result in even larger amounts of palm oil mill effluent (POME), estimated at nearly three times the quantity of crude palm oil. Normally, POME is treated using end-of-pipe processes, but it is worth considering the potential value of POME prior to its treatment through introduction of a cleaner production. It is envisaged that POME can be sustainably reused as a fermentation substrate in the production of various metabolites, fertilizers and animal feeds through biotechnological advances. The present paper thus discusses various technically feasible and economically beneficial means of transforming the POME into low or preferably high value added products.

Typical conversion of lignocellulosic biomass into reducing sugars using dilute acid hydrolysis and alkaline pretreatment

Abstract The development and production of fossil fuel alternatives have become one of the main focal points in recent investigations. Lignocellulosic biomass is a renewable source of fermentable sugars for second-generation biofuels and chemicals via biotechnological pathways. However, the presence of lignin and hemicellulose in lignocellulosic biomass makes it difficult for the biomass to be hydrolyzed or digested during fermentation. Thus, effective biomass pretreatment is vital. The present review shows that chemical pretreatment is the current preferred method to obtain high sugar yields at low cost, with dilute acid and alkaline hydrolysis as the two most reported technologies. Dilute acid favours hydrolysis of the hemicelluloses whereas alkaline hydrolysis targets the lignin fraction. Both methods have merits and demerits, and have been combined with other treatments such as hydrothermal and enzymatic hydrolysis. Further investigation is required to improve the pretreatment processes and to ensure the economic viability of bioconversion.

Predicting flux and rejection of multicomponent salts mixture in nanofiltration membranes

Abstract This paper presents a modified Donnan-Steric-Pore model (DSPM) to predict the rejection of mixture of NaCI:Na2SO4 in nanofiltration (NF) membrane based on the extended Nernst-Planck equation with the incorporation of charge and steric effects for the transport of ions inside the membrane and incorporation of concentration polarization effect for mixture of ions/solutes. With this approach, the permeate flux can be calculated based on the concentration of ions at the membrane surface. The membrane performance was modelled using three parameters namely; effective pore radius, rp , effective ratio of embrane thickness to porosity, Δx/Ak, and the effective charge density, Xd. The simulation results shows that the model can predict the tendencies and patterns of rejection and flux reduction behaviour reasonably well for system containing NaCl:Na2SO4. The model can be used as a preliminary tool to assess the rejection capability as well as the flux behaviour of NF membranes in mixtures of solutions. For future works, the model can be improved further to account for non-ideal as well as real mixture solutions.

Recent Advances in the Application of Inorganic Salt Pretreatment for Transforming Lignocellulosic Biomass into Reducing Sugars

Currently, the transformation of lignocellulosic biomass into value-added products such as reducing sugars is garnering attention worldwide. However, efficient hydrolysis is usually hindered by the recalcitrant structure of the biomass. Many pretreatment technologies have been developed to overcome the recalcitrance of lignocellulose such that the components can be reutilized more effectively to enhance sugar recovery. Among all of the utilized pretreatment methods, inorganic salt pretreatment represents a more novel method and offers comparable sugar recovery with the potential for reducing costs. The use of inorganic salt also shows improved performance when it is integrated with other pretreatment technologies. Hence, this paper is aimed to provide a detailed overview of the current situation for lignocellulosic biomass and its physicochemical characteristics. Furthermore, this review discusses some recent studies using inorganic salt for pretreating biomass and the mechanisms involved during the process. Finally, some prospects and challenges using inorganic salt are highlighted.

Recent Advances in the Reuse of Wastewaters for Promoting Sustainable Development

Substantial research and development as well as application have been devoted to wastewater. This includes wastewater minimization and treatment, environmental assessment of wastewater, minimization of the environmental impact, and life cycle assessment. The primary reason for these efforts is that wastewater generation constitutes one of the major environmental issues encountered by production industries. Wastewater management through end-of-pipe processes has traditionally been aimed solely at reducing the concentration of pollutants. However, in a world of increasing water demand, wastewater reclamation and reuse are becoming a popular practice worldwide, thus mirroring rapid changes in environmental policies for promoting sustainability in water resource management. From a theoretical point of view, reuse of wastewater addresses both water supply and pollution issues, thus reducing the net demand and discharges into environment. In addition, if the reuse management is properly planned and implemented, an acceptably low risk to human health can also be achieved. Therefore, it is worth considering the potential value of wastewater prior to its treatment through the introduction of wastewater reuse. This chapter discusses various technically feasible and economically beneficial ways of transforming wastewater into low- or preferably high-value-added products, such as industrial and irrigation waters, fermentative metabolites, fertilizers, and animal feeds.

Performance of Nanofiltration Membranes in the Treatment of Synthetic and Real Seawater

Abstract Nanofiltration membranes (NF) are being employed in pretreatment unit operations in both thermal and membrane seawater desalination processes and as partial demineralization to seawater. In order to predict NF membrane performance, a systematic study on the filtration performance of selected commercial NF membranes against seawater is presented in this paper. Two commercial nanofiltration membranes (NF90 and NF270) have been investigated in details to study their performance in filtering the salt mixture, synthetic and real seawater in a cross‐flow NF membrane process at a pressure range from 4 to 9 bars. The Spiegler‐Kedem model was used to fit the experimental data of rejection with the permeate flux in order to determine the fitting parameters of the reflection coefficient (σ) and the solute permeability (Ps). The results showed that the rejection increases with pressure for NF90 and slightly increases with pressure for NF270. Also, the NF90 membrane has shown to be able to reject both monovalent and divalent of all investigated mixtures and seawater with very reasonable values but at a relatively low flux. Moreover, it reduced the salinity of investigated seawater from 38 to 25.5 g/L using one stage of the NF membrane at 9 bars. This makes NF90 more suitable for the application in the pretreatment of desalination processes. On the other hand, NF270 can reject monovalent ions at relatively low values and divalent ions at reasonable values. It has also reduced the seawater salinity to 33.6 g/L, but at a very high permeate flux. The SKM model fitted the experimental data of divalent ions in salt mixture and seawater.

Nanofiltration of Magnesium Chloride, Sodium Carbonate, and Calcium Sulphate in Salt Solutions

Abstract Nanofiltration (NF) membranes have been employed in pre‐treatment unit operations in both thermal and membrane seawater desalination processes. This has resulted in reduction of chemicals used in pretreatment processes as well as lowering the energy consumption and water production cost and, therefore, has led to a more environmentally friendly processes. In order to predict NF membrane performance, a systematic study on the filtration performance of selected commercial NF membranes against brackish water and seawater is required. In this study, three commercial nanofiltration membranes (NF90, NF270, N30F) have been used to treat highly concentrated different salts solutions (MgCl2, Na2CO3, and CaSO4) at salinity level similar to that of brackish water and seawater. The main parameters studied in this paper are salt concentration and feed pressure. The experimental data were correlated and analysed using the Spiegler‐Kedem model. In particular, the reflection coefficient (σ) of all studied membranes and the solute permeability (Ps) have been determined for all membranes and at different salinity levels of studied salts. All the studied membranes fitted the model well for all investigated salts except the experimental data of MgCl2 using N30F membrane, which did not fit well at low rejection. The results showed that NF90 produced a high rejection around 97% for all salts with medium permeate flux while NF270 gave a high flux with medium rejection and N30F gave low rejection and flux.

Utilization of self-synthesized ZnO nanoparticles in MPR for industrial dye wastewater treatment using NF and UF membrane

AbstractThis study attempted to use zinc oxide (ZnO) nanoparticles in membrane photocatalytic reactor (MPR) for industrial dye wastewater treatment. Performance comparison of nanofiltration (NF) and ultrafiltration (UF) in the MPR system were investigated to produce cleaner discharge and to retain the ZnO for reuse. From the results, the optimum operational condition of MPR occurred under pH 11 and 0.1 g L−1 of ZnO loading. NF membrane performance improved after the addition of ZnO nanoparticles in the wastewater; in terms of normalized flux reduction (65%), colour removal (100%), chemical oxygen demand (92%), turbidity reduction (100%) and total suspended solid rejection (100%). In contrast, UF membrane showed worse performance, due to the permeation of dye molecules and nanosized ZnO across the UF membrane pores. Membrane characterizations of field emission scanning electron microscopy and energy dispersive X-ray results confirmed that the ZnO nanoparticles and NF membrane application has a great potent...

Role of energy irradiation in aiding pretreatment of lignocellulosic biomass for improving reducing sugar recovery

Abstract With the depletion of crude oil reserves, the ever-increasing global energy consumption encourages the efforts to find alternative renewable sources for production of biofuels and value-added chemicals. The conversions of lignocellulosic biomass into biofuels and commodity chemicals via the biotechnological pathway have been the recent trend. Specifically, these products can be obtained through fermentation of reducing sugars, which are the main but basic derivatives from the biomass. In order to overcome the recalcitrant structure of the biomass for effective reducing sugar recovery, a pretreatment stage is normally required. Currently, one of the most novel forms of biomass pretreatment is using energy irradiation methods such as electron beam, gamma ray, pulsed electrical field, microwave and ultrasound. In general, these technologies are often used together with other more conventional chemical and/or biological pretreatment techniques for enhancing sugar recovery. Nevertheless, energy irradiation offers significant improvement in terms of possible cost reduction opportunities and reduced toxicity. Hence, this review highlights the recent studies of using energy irradiation for pretreating biomass as well as the industrial applications of reducing sugars in biotechnological, chemical and fuel sectors. In short, more research needs to be done at the scientific, engineering and economic levels to make energy irradiation one of the front runners in the field of biomass pretreatment.