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The aim of this study is to utilise recycled aluminium, expanded polyethylene (EPE) and expanded polystyrene (EPS) to develop a ternary composite. The study was a preliminary investigation into the microstructural, functional groups and textural properties of the novel material. The material was characterised by Fourier Transform Infra-Red Spectroscopy (FTIR), Scanning Electron Microscopy with Energy Dispersive X-ray analysis (SEM-EDX) and Branueur-Emmet-Teller analysis (BET). The shifts in the FTIR peaks for each of the polymer feedstock in comparison with the binary composite indicated chemical interactions between them. For the ternary composites, there were shifting of peaks as the proportion of the aluminium increased in the composites, suggesting the influence of aluminium on the curing process. Beyond 20% Al filler, there were no significant functional group changes in the composite. SEM revealed that an increase in aluminium filler percentage led to better interfacial adhesion and dispersion. BET revealed that the blend of polystyrene and powdered EPE reduces the surface area, while the introduction of the aluminium particles within the range observed increases the surface area of the hybrid composites formed. As the dispersion of aluminium increased, pore volume increased while pore size decreased.

Polymer composites have recently received a considerable amount of scientific and technological interest, because their properties can be properly controlled, choosing the adequate doped particles,...

Biodiesel production waste cooking oil is usually limited by its high free fatty acid and moisture content. The synergetic effect of both base and acid source from biomass was employed to proffer way out to this challenge. This study shows the coupled development of sulfonated carbonized corn cob (S-CCC) and calcined cow-bone (C-CB) catalysts for transesterification of waste cooking oil. The catalyst was prepared by physically mixing several mass percentages of S-CCC and C-CB (fluorapatite) in strategic proportions. The maximum biodiesel yield of 96.2 % was attained for catalyst mixture of 60 wt% and 40 wt%. The developed catalyst mixture was characterized by Fourier Transform Infrared Ray (FTIR), powder X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Brunauer–Emmett-Teller (BET). The surface area (472.3 m2/g), pore size (2.4330 nm) and volume (0.1380 cc/g) were obtained for the catalyst. The XRD shows that the crystallized structure of the bifunctional catalyst was formed majorly between 2 theta 10 and 65.Also the SEM shows a well dispersive pattern of the particles of the catalyst. The developed catalyst was employed for biodiesel optimization studies by varying factors such as time, temperature, catalyst loading and methanol: oil using optimal design under the response surface methodology. Maximum yield of 98.98 % was attained at time 6 h, temperature 65 °C, catalyst loading 6 %wt/ wt of oil and methanol to oil ratio of 11.75:1. It was observed that time and temperature had notable effect on the biodiesel yield.

The performance of factorial designs is still limited due to some uncertainties that usually intensify process complexities, hence, the need for inter-platform auto-correlation analyses. In this study, the auto-correlation capabilities of factorial designs and General Algebraic Modeling System (GAMS) on the effects of some pertinent operating variables in wastewater treatment were compared. Individual and combined models were implemented in GAMS and solved with the trio of BARON, CPLEX and IPOPT solvers. It is revealed that adsorbent dosage had the highest effect on the process. It contributed the most effect toward obtaining the minimum silica and TDS contents of 13 mg/L and 814 mg/L, and 13.6 mg/L and 815 mg/L from factorial design and GAMS platforms, respectively. This indicates a concurrence between the results from the two platforms with percentage errors of 4.4% and 0.2% for silica and TDS, respectively. The effects of the mixing speed and contact time are negligible.

The worldwide increase in consumption of energy and resources has led to various unsustainable developments which has called for the development of sustainable use of resources and reduction in energy consumption. Natural fibre reinforced composites that are synthesised and cured at room temperatures appears to be a fulfilment for this need towards achieving truly sustainable and optimised development processes of high importance. This study was aimed at demonstrating the viability of plantain fibres and solvated polystyrene resin in preparing composites. Plantain Fibre Polystyrene Composites were prepared using hand lay-up method with untreated fibres and fibres treated with 1.5–4.5% NaOH; three levels of fibre content (5 wt%, 10 wt% and 15 wt%); and three levels of fibre length (2 mm, 4 mm and 6 mm). The composites were characterized for their tensile strength, functional groups and surface morphology. It was observed that treated plantain fibres have better adhesion to polystyrene resin compared to the untreated fibres. It was also observed that untreated fibre composites gave a higher tensile strength compared to treated fibre composites.

Mixed solid oxides are known for their excellent catalytic property and applications in environmental remediation. This study presents a green-synthesis route for magnesium oxide–titanium oxide, a mixed oxide here demonstrated to possess high performance of phenol removal from hydrocarbon refinery process wastewater. Mixed oxide (MgO-TiO2) was prepared by using the whole extract from leaves of Piliostigma Thonningii as reducing agent. A structural attribute of the mixed oxide was investigated using X-ray Diffractometer, High-Resolution Scanning Electronic Microscopy and Energy Dispersive X-ray. Petroleum refinery raw wastewater having phenol concentration of 19.961 mg/L was treated using the green-synthesized mixed oxide. Adsorptive phenols removal up to 99.5% was achieved with a dosage of 0.04 g/100 mL at temperature of 35 °C, and contact time of 1.167 h. By this, the treated water meets the standard acceptable phenol concentration (0.1 mg/L) in wastewater of hydrocarbon refinery.

The Offshore Safety Permit (OSP) Program is the Personnel Accountability System, being utilized by the Nigerian Oil and Gas Industry Regulator, in line with global best practices to manage the details of over 40,000 oil workers registered to work on offshore and swamp facilities and track their movements to-and-fro such facilities. The Program was introduced in 2012 to standardize requirement for personnel travel to offshore and swamp locations and to eliminate issues such as: non-compliance with mandatory competency and safety training; non-compliance with medical fitness to work requirement; unauthorized extended stay on facilities at offshore/remote location; inaccurate documentation of personnel movement to-and-fro facilities at offshore/remote location leading to delayed/wrong incident reporting. This paper examines, through the review of the OSP policy, Guidelines and database, the value addition of the program since its inception., detailed and insightful discussions are made on the importance and potentials of the OSP program as a simple but integral policy and planning tool in managing risks, enhancing collaboration and improving safety and emergency services in Nigeria's oil and gas industry.

A systematic study of the diffusion mechanism and effect of mass transfer limitation during the adsorption of CO2 onto polyaspartamide is presented using a differential adsorption bed method, carri...

Banana (Musa Spp.) is a widely cultivated fruit in tropical West Africa and it generates a lot of waste due to its single fruit production per lifecycle and relatively large plant size. The recover...

The concept of Safety Case administration in oil and gas operations was one of the important fallouts from the public enquiry of Piper Alpha incident which happened in 1988 in the North Sea and claimed the lives of more than one hundred and fifty (150) personnel. Safety Case is a document which its process of preparation and approval ensures that operators or facility owners not only become aware of hazards in their operations but also put in place adequate mitigations to reduce the risk of accident occurrence to as low as reasonably practicable (ALARP), thereby assuring themselves and demonstrating to stakeholders (especially the relevant regulatory authority) that their facility is safe to operate or safe to continue in operation. Against this backdrop, the government has made the development and implementation of Safety Case a requirement for all installations operating, or to be operated, or to be decommissioned in the Nigerian oil and gas industry. Nigeria’s oil and gas industry regulator (Department of Petroleum Resources – DPR) established the Safety Case Regime as a means of ensuring, validating and tracking measures put in place by operators and facility owners towards mitigating the inherent risks posed by their oil and gas installations in Nigeria. This paper therefore examines the key elements as well as benefits in the implementation of the Safety Case regime in Nigeria by evaluating the extent of compliance amongst the operators and identifying common problems facing operators in the preparation of a Safety Case for submission. The basic contents of a typical safety case, step-by-step implementation procedure, and the approval criteria were reviewed with recommendations made to improve the overall process.

Plantain stalks obtained from solid waste stream of Ganmo market in Ilorin was used in this study. Natural fibres extraction from waste plantain stalk was achieved using biological retting methods. The natural fibre was rented from the waste stalk after 24 days of soaking in water. The extracted fibres were exposed to 2, 4 and 6% alkali solution (NaOH) treatment for two hours, washed and dried in the oven for 7 hours. Elemental analysis of raw plantain fibres showed the presence of elements like Indium, Potassium, Silicon and Calcium among others. Tensile strength analysis of the fibres, for single fibre strands showed that the 2% treated fibre showed distinctly promising potential with the highest tensile characteristics of young modulus, stress at break and force at peak of 52864.366N/mm2, 5398.536N/mm2 and 2.650N, respectively. Evaluation of the chemical composition of plantain by FTIR spectroscopy indicated that treatment of natural fibres using NaOH beyond 2% have a negative impact on the plantain fibre properties. Through alkali exposure, the fibre configuration presents small variations in composition. It is consequently apparent that alkali treatment with concentration of less than 2% NaOH is sufficient to remove hemicelluloses and to obtain the optimum tensile effect.

The use of Ppolystyrene-Bbased Rresin (PBR) synthesised from waste polystyrene in the valorisation of biomass like sawdust, rice husk and bamboo for the production of plastic composites at ambient conditions was the focus of this investigation. This chapter explores the preparation and properties of plastic composites produced from biomass wastes and PBR synthesised from waste. The preparations were made at varying percentage of waste biomass (between 0% and 40%). PBR was synthesised via solvolysis of waste polystyrene in a chosen solvent, and properly mixed with recycled biomass by simple mechanical stirring, using hand lay-up process in cold pressing to obtain the desired shapes. ASTM D-1037 standard was used to evaluate the physical and mechanical properties of the manufactured particleboards. Moisture content (MC), water absorption (WA), thickness swelling (TS) and mechanical properties, that is modulus of elasticity (MOE) and modulus of rupture (MOR), were suitably comparable to ANSI A208.1 standard. PBR synthesised at room temperature is confirmed as a good matrix for biomass fillers like sawdust, rice husk and bamboo in the production of plastic composite.

The development of new, efficient and cost-effective technologies for acid gases (CO2 and H2S) removal from natural gas is pertinent for cleaner energy productions. The removal of acid gases from n...

This study investigates the utility of a hybrid adsorption-membrane process for cake compressibility evaluation of biotreated palm oil mill effluent (BPOME). A low-cost empty fruit bunch (EFB) based powdered activated carbon (PAC) was employed for the upstream adsorption process with operation conditions of 60 g/L PAC dose, 68 min mixing time, and 200 rpm mixing speed to reduce the feed-water strength and alleviate probable fouling of the membranes. Two polyethersulfone microfiltration (MF) membranes of 0.1 and 0.2 μm pore sizes were investigated under constant transmembrane pressures (TMP) of 40, 80, and 120 kPa. The compressibility factors (z), which was obtained from the slopes of power plots (function of specific cake resistance (α) and pressure gradient) were evaluated. The z values of 0.32 and 0.52, respectively obtained, for the 0.1 and 0.2 μm MF membranes provided compressible and stable z values as observed from their power plots. Besides, these membranes were found suitable for the measurement of z since the results are in consonance with the established principle of cake compressibility. Moreover, the upstream adsorption mitigated the clogging of the membranes which ultimately led to moderate resistances and cake compressibility. These are indications that with the secondary cake filtration, a sustainable flux can be achieved during BPOME filtration. The membranes exhibited close to 100% restoration after cleaning.

In process systems engineering, it is critical to design an effective and optimized process in a short period with minimum experimental trials. However, improvement of some process variables may deteriorate some other criteria due to conflicting regions of factor interests for optimal solution in multi-objective optimization (MOO) processes. Here, the global optimization of an adsorption case study with conflicting optimal solutions based on multi-objective Response Surface Methodology (RSM) design is facilitated with the implementation of BARON solver based on General Algebraic Modeling System (GAMS) with identical factor variables, levels, and model equations. RSM suggested fifteen different optimum settings of which the validation is quite expensive and onerous, whereas GAMS suggested a single optimum setting which makes it more economically viable especially for large scale systems. In addition, the GAMS-based optimization provided more accurate and reliable results when experimentally validated as compared to the RSM-based solution.

An integrated low-cost adsorption (with powdered activated carbon, PAC) and cross-flow membrane filtration (with microfiltration membranes of 0.1 and 0.2 μm pore sizes) process was employed for the treatment of biotreated palm oil mill effluent (POME) to produce irrigation water that is fully benchmarked with water-quality standards. The permeate quality was within the recommended standard for irrigation water, as the concentrations of all critical constituents were well below their recommended values. Sustainability of the process integration was further confirmed with the domination of cake filtration over other blocking mechanisms with higher R2 values at all trans-membrane pressures. Suitable extended usage of permeate was found for toilet/urinal flushing.

Availability of quality-certified water is pertinent to the production of food and pharmaceutical products. Adverse effects of manganese content of water on the corrosion of vessels and reactors necessitate that process water is scrutinized for allowable concentration levels before being applied in the production processes. In this research, optimization of the adsorption process conditions germane to the removal of manganese from biotreated palm oil mill effluent (BPOME) using zeolite 3A subsequent to a comparative adsorption with clinoptilolite was studied. A face-centered central composite design (FCCCD) of the response surface methodology (RSM) was adopted for the study. Analysis of variance (ANOVA) for response surface quadratic model revealed that the model was significant with dosage and agitation speed connoting the main significant process factors for the optimization. R(2) of 0.9478 yielded by the model was in agreement with predicted R(2). Langmuir and pseudo-second-order suggest the adsorption mechanism involved monolayer adsorption and cation exchanging.

In this study, the effects of powdered Aluminium (Al) as reinforcing fillers for polystyrene-based resin (PBR) matrix has been evaluated based on the analysis of mechanical and structural properties. Samples were prepared by hand lay-out technique enhanced with the usage of single roller. The PBR was reinforced by Aluminium powders (μm) at selected weight fractions of (0, 5, 10, and 15 %) and investigated by X-ray diffraction (XRD) physical and mechanical testing. The study of mechanical properties includes: elongation at break, time to failure and young modulus. The XRD studies confirmed no chemical reaction but rather the introduction of crystalline structure in the polystyrene matrix based on the amount of Aluminium content and the even distribution of aluminium powder in the matrix. The tensile strength increased with increasing filler content; however elongation at break and time to break showed decrement as the weight fraction of aluminium powder is increased in the composites. DOI: http://dx.doi.org/10.5755/j01.erem.74.2.19680

Despite the widely documented excellent purification capacity of membranes, their main drawback—fouling—is still being extensively researched with a view to finding a sustainable solution. Fouling simply implies the process that results in the performance loss of a membrane due to the deposition of suspended or dissolved matters onto its external surface or the internal pore walls [1]. Fouling eventually leads to a reduction in the active area of the membrane and thereby results in a reduction in flux below the theoretical capacity of the membrane. Fouling or pore-blocking has been identified as the main reason limiting the adoption of membrane purification processes by many industries. Consequently, an apt understanding of the pore-blocking mechanisms of membranes is imperative, as it is a pertinent factor dictating the overall performance of the filtration process. Pore blockage can occur in any of the two commonly known membrane operations: constant-pressure and constant-flux rate. In a constant-pressure operation, pore blockage usually leads to a sharp decline in permeate flux, while a severe pressure rise is usually encountered in a constant-flux rate operation. In principle, governing filtration models can facilitate the design of membrane processes more than any experiment or characterization can, yet data from experiments are usually required for validation purposes [2–5]. To properly control particulate fouling at the design stage, as well as appropriately monitor it during a plant operation, the methods utilized in evaluating the particulate content of feed-water in predicting membrane fouling are crucial. Soluble and colloidal materials are assumed to be responsible for membrane pore blockage, while suspended solids are mainly accountable for the cake layer resistance [4,6,7]. To accurately measure and predict particulate fouling, it is recommended that specific fouling mechanisms/indices be investigated with respect to specific membranes since the Modified Fouling Index (MFI), where a 0.45 μm membrane filter is used and usually represented as MFI0.45, cannot represent all membrane types. This is due to the fact that some principal parameters such as retention of smaller particulates, the nature and concentration of solutes and solvents, proof of cake filtration, pore size distribution, surface morphology, module hydrodynamics and membrane type/material must be considered in such investigations [1,8]. Therefore, in any proposed membrane process with plans for sustainability, pore-blocking modeling is germane for the determination of some key factors necessary for the design of an efficient membrane system. These factors are: (1) the description of the extent of membrane fouling in terms of particle accumulation at the membrane surface or inside the membrane pores; (2) the prediction of the fouling potential of a specific feed with respect to a specific membrane; and (3) the identification of the most appropriate and sustainable cleaning method necessary for the membrane process. In this study, a systemic investigation was carried out on high-strength agro-industrial wastewater to describe the successive steps involved in the flux decline of a membrane filtration process in terms of pore-blocking mechanism. Microfiltration (MF) and ultrafiltration (UF) membranes, which are the popular low-pressure membranes (LPMs), were utilized for the filtration of the high-strength wastewater. The wastewater is specifically a discharge of an end-of-pipe treatment process from the agro-industry palm oil milling process. An upstream adsorption process was applied to lower the feed strength and reduce its fouling effects on the membranes. The investigative experiments were conducted in a constant-pressure and cross-flow filtration mode through polyethersulfone (PES) MF (pore sizes: 0.1 and 0.2 μm) and UF (molecular weight cut-off: 1, 5 and 10 kDa) membranes at the transmembrane pressures of 40, 80 and 120 kPa. The examined results within the frame of the common blocking mechanisms revealed that the blocking index, η, decreased from 2 to 0 in all five membranes. The pore-blocking phenomenon was successively observed from the complete blocking mechanism (i.e., η = 2) down to the cake filtration mechanism (i.e., η = 0). Furthermore, there is an indication that the early blockage of the pores and formation of a cake resulted in a limiting cake height evident from the near-constant trend of the permeate flux. This means that cake filtration could be best used to explain the fouling mechanisms of the feed on the LPMs based 139Modeling of Pore-Blocking Behaviors of Low-Pressure Membranes on the coefficient of determination (R2) values at all applied pressures. This further demonstrates that the fouling is primarily caused by the gradual reversible cake deposition, which could be easily removed by less onerous cleaning methods.

Electroforced sedimentation (EFS) is a well-known technique for enhancing the solid content of the final sludge cake. However, the parameters affecting the performance of EFS and quality of the resulting sludge cake, as well as the removed water, are not sufficiently studied. In this research, a mixture of zinc oxide (representing sludge) and polyacrylamide (dewatering aid) were used as experimental materials. The process parameters of electroforced sedimentation were optimized using a design of experiment software (Design Expert ® Version 7.0.0) with a face-centered central composite design (FCCCD) under response surface methodology. An optimization study was carried out for the output response (sedimentation velocity) based on three process factors and an empirical model was developed. The optimized values for current density, total solid volume per unit cross-sectional area and polyacrylamide dose for the highest sedimentation velocity (0.0199 cm/min) were 6.0 A/m2, 7.74 mm and 1.53 % (based on the weight of zinc oxide), respectively. The overall model was significant with Prob > F value of 0.0117 and R 2 value of 0.8911 while the most significant parameter was observed to be the current density with a Prob > F value of 0.0004. Validation experiments were conducted to confirm and measure the accuracy of the models for the three set of parameters including optimum parameters. The error was within the limit of prediction accuracy, and the sedimentation velocity was enhanced by the addition of 1.53 % PAM as dewatering aid. Thus, it was concluded that EFS can be applied successfully for materials having permanent charge.

Coupled with the highly voluminous wastewater – palm oil mill effluent (POME) – usually produced during the palm oil processing, there are also abundant solid wastes such as empty fruit bunch (EFB) from the industry that could be converted to value added products such as low cost adsorbents like activated carbons. These adsorbents could well fit into low budget treatment process integration with better sustainability if improved. In this study, the EFB-based powdered activated carbon (PAC) was produced in a two-way step; carbonization and steam activation (pyrolysis) to be applied in the treatment of biotreated POME (BPOME). The pyrolysis was carried out at 900 °C and steam flow rates of 2.0 mL/min, 4.0 mL/min, 6.0 mL/min, 8.0 mL/min and 10.0 mL/min for 15 min activation time. Through one-factor-at-a-time (OFAT) method, the 8.0 mL/min steam flow rate was identified as best flow rate because it led to an activated carbon with higher Brunauer–Emmet–Teller (BET) surface area of 886.2 m 2 /g coupled with better adsorption efficiency of 95% and 90% removals for manganese (Mn) and hydrogen sulphide (H 2 S), respectively. This high uptake efficiency is due to, amongst other factors, improved pore architecture. Moreover, extensive physicochemical characterization of the PAC in terms of, but not limited to Fourier Transform Infra-red (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), particle size and distribution analysis were carried out, and there were indications of characteristic improvements when compared to our previous investigation. Optimization studies revealed that 5 g PAC/100 mL BPOME, 200 rpm agitation speed and 60 min of sorption time brought about the best removal of both Mn and H 2 S. Equilibrium studies also revealed that Langmuir isotherm model fitted better with the adsorption data in describing the adsorption behavior.

Biosorption of chemical oxygen demand (COD), manganese (Mn) and hydrogen sulphide (H2S) onto an empty fruit bunch (EFB)–based powdered activated carbon (PAC) from a multicomponent system—biotreated palm oil mill effluent (BPOME)—were studied in a batch adsorption process. The experimental results were fitted to four isotherm models, and four kinetic models. Amongst the isotherm models (Langmuir, Freundlich, Temkin and Dubinin-Radushkevich) employed, Langmuir model showed the best conformity to the equilibrium data with R 2 values of 1.00 for COD and 0.9999 for both Mn and H2S. The Dubinin–Radushkevich model followed the conformity trend with R 2 values of 0.9984, 0.9948 and 0.9824 for COD, H2S, and Mn, respectively. Also, amongst the kinetic models (Pseudo-first order, Lagergren’s pseudo-second order, Elovich and Weber–Morris intra-particle diffusion) employed, only the pseudo-second order model could best describe the adsorption behaviours of all the three contaminants with R 2 values of 1.00 in all cases. The mechanistic uptake pathway was further examined by means of the Fourier transform infrared in studying the surface chemistry of the PAC. It was observed that the presence of functional groups like the aldehydes and ketones, carbonyl, mono-alkyl, amines, amongst others led to physicochemical interactions between PAC surface and the contaminants. Overall, the equilibrium, kinetics and surface chemistry analyses pointed towards the adsorption processes been largely driven by electrostatic sorption. Additionally, the EFB-based PAC was capable of reducing COD, Mn and H2S from POME, hence, could be utilized in developing a unit operation for integration into the current POME treatment. Percent uptake versus adsorption time plot for COD, Mn and H2S removal from biotreated POME.

In this investigation, the potential of powdered activated carbon (PAC) derived from empty fruit bunch (EFB) precursor through pyrolysis method for chemical oxygen demand (COD) adsorption from biotreated palm oil mill effluent (POME) was extensively studied. The PAC was prepared and characterized using scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy and Brunauer–Emmett–Teller. The SEM microphotographs showed opened micropores existing in the PAC structure with a surface area of 886.2 m2/g. The FTIR spectra revealed the three major peaks exhibited by the surface of the activated carbon at exactly wavenumbers of 1737.61, 1365.10 and 1216.91 cm−1. This suggests the presence of some functional groups which can potentially enhance positive interactions between the adsorbent and the adsorbate. Design-Expert ® software (version 7.0.0) was employed for the statistical experimental design of a two-step optimization: factorial and response surface methodology. Maximum COD reduction of 84 % (227 ppm residual) was achieved from an initial concentration of 1387 ppm. This study being the first optimization process with the utility of EFB-based PAC in the treatment of the high-strength multicomponent biotreated POME; hence, the results could serve as requisite data for upscaling and/or future investigations in the utility of the precursor as a viable adsorbent.

The prevalent global issue on environmental pollution and the growing desire for polymer based composite materials has given rise to increasing research in the production of composite containing natural organic fillers. This study describes the optimization of impact strength of plastic composites developed from polystyrene and natural fibre wastes(sawdust and rice husk) using 3-level-factoral-design via hand lay-up method studying the effect of filler concentration (15 – 45 %), filler size (20 – 100 µm) and alkaline treatment concentration (2 – 6 %) on the impact strength of polystyrene fibre reinforced composite. Models were developed using response surface methodology to predict impact strength of the composite as a function of the process variables investigated. The optimization of the process parameters show that the optimum condition for obtaining high impact strength are 15% filler concentration, 100 µm filler size and 4% alkaline (NaOH) concentration in saw dust filled composite while a filler concentration of 15%, filler size of 31µm and an alkaline concentration of 2% for the rice husk filled composite. The recycled polystyrene in combination with wood dust and rice husk has produced a polymer composite with moderate impact strength applicable in various applications.

World natural resources are now going into extinction as evident from the accelerating depletion of our water resources through the persistent but exorable pollutions confronting our water environment daily. Despite this, some part of the world still witnesses overwhelming wastage of fresh water due to lack of proper motivation towards water management policies from the policy makers as well as professionals. Malaysia as a country was known as a place of huge amount of fresh water coupled with regular rainfalls around the year but now witnessing depletion in its fresh waters due to environmental pollution. One of the main causes of this pollution is the palm oil industry which discharges its Biotreated Palm Oil Mill Effluent (BPOME) into the rivers after little but insufficient treatments. This paper reviews the status, rationale and potential of water reuse in Malaysia. The piece further reflects the potential of advanced technologies to produce regenerated water offering specific solutions to industrial or agricultural reuse needs from BPOME, thus suggesting potential, affordable and cost effective water conservation systems through zero liquid discharge (ZLD) technology and water reclamation from BPOME discharge.

This study has applied the concept of the hybrid PAC-UF process in the treatment of the final effluent of the palm oil industry for reuse as feedwater for low-pressure boilers. In a bench-scale set-up, a low-cost empty fruit bunch-based powdered activated carbon (PAC) was employed for upstream adsorption of biotreated palm oil mill effluent (BPOME) with the process conditions: 60 g/L dose of PAC, 68 min of mixing time and 200 rpm of mixing speed, to reduce the feedwater strength, alleviate probable fouling of the membranes and thus improve the process flux (productivity). Three polyethersulfone ultrafiltration membranes of molecular weight cut-off (MWCO) of 1, 5 and 10 kDa were investigated in a cross-flow filtration mode, and under constant transmembrane pressures of 40, 80, and 120 kPa. The permeate qualities of the hybrid processes were evaluated, and it was found that the integrated process with the 1 kDa MWCO UF membrane yielded the best water quality that falls within the US EPA reuse standard for boiler-feed and cooling water. It was also observed that the permeate quality is fit for extended reuse as process water in the cement, petroleum and coal industries. In addition, the hybrid system’s operation consumed 37.13 Wh m−3 of energy at the highest applied pressure of 120 kPa, which is far lesser than the typical energy requirement range (0.8–1.0 kWh m−3) for such wastewater reclamation.

Sorption optimization and mechanism of hardness and alkalinity on bifunctional empty fruit bunch-based powdered activation carbon (PAC) were studied. The PAC possessed both high surface area and ion-exchange properties, and it was utilized in the treatment of biotreated palm oil mill effluent. Batch adsorption experiments designed with Design Expert(®) were conducted in correlating the singular and interactive effects of the three adsorption parameters: PAC dosage, agitation speed and contact time. The sorption trends of the two contaminants were sequentially assessed through a full factorial design with three factor interaction models and a central composite design with polynomial models of quadratic order. Analysis of variance revealed the significant factors on each design response with very high R(2) values indicating good agreement between model and experimental values. The optimum operating conditions of the two contaminants differed due to their different regions of operating interests, thus necessitating the utility of desirability factor to get consolidated optimum operation conditions. The equilibrium data for alkalinity and hardness sorption were better represented by the Langmuir isotherm, while the pseudo-second-order kinetic model described the adsorption rates and behavior better. It was concluded that chemisorption contributed majorly to the adsorption process.

Carbon nanofibers (CNFs) were synthesized through nickel ion (Ni2+) impregnation of powdered activated carbon (PAC). Chemical Vapor Deposition (CVD) using acetylene gas, in the presence of hydrogen gas, was employed for the synthesis process. Various percentages (1, 3, 5, and 7 wt. %) of Ni2+catalysts were used in the impregnation of Ni2+into PAC. Field Emission Scanning Electron Microscope (FESEM), Fourier Transform Infrared (FTIR) Spectroscopy, Energy Dispersive X-Ray Analyzer (EDX), Transmission Electron Microscopy (TEM), Thermal Gravimetric Analysis (TGA), zeta potential, and Brunauer, Emmett, and Teller (BET) were utilized for the characterization of the novel composite, which possessed micro and nanodimensions. FESEM and TEM images revealed that the carbonaceous structure of the nanomaterials was fibrous instead of tubular with average width varying from 100 to 200 nanometers. The PAC surface area increased from 101 m2/g to 837 m2/g after the growth of CNF. TGA combustion temperature range was within 400°C and 570°C, while the average zeta potential of the nanocomposite materials was −24.9 mV, indicating its moderate dispersive nature in water.

Freshwater has become the blue gold of the 21st century due to its continuous depletion resulting from expanding population, shifting climates, urbanization and industrialization, and waterways pollution. Water reclamation is an orthodox alternative drought-proof source of water, and utility of membrane technology seems indispensable to every effective reclamation and reuse program due to its excellent features. However, fouling is a limiting factor of membrane separations, and in order to control particulate fouling at the design stage and plant operation monitoring, tools utilized in evaluating the particulate content of feed-water in predicting membrane fouling are vital. Subsequent to an adsorption process, a downstream cross-flow microfiltration (MF) membrane process was carried out on the final discharge effluent of palm oil mill industry at constant transmembrane pressures (TMPs) of 40 kPa, 80 kPa, and 120 kPa for 60 min filtration time using MF membranes of 0.1 and 0.2 μm pore sizes. Darcy's law and Hermia's blockage models were fitted to the experimental data and it was observed that cake filtration could be best used to explain the fouling mechanisms of effluent on the membranes based on the R2 values generated for the two MF membranes at all TMPs, however, not without the complete, standard and intermediate blocking mechanisms contributing at the onset of the filtration process. This demonstrates that the fouling was as a result of gradual reversible cake deposition which could easily be removed by less onerous cleaning methods. This data could serve as requisite for future upscaling of membrane processes for characteristically similar effluents with the aim of achieving sustainable fluxes.IntroductionIn the past few years, membrane filtration has been applied in the treatment of wastewaters especially in situations where cleaner water quality are sought. The populous utility of the membrane technology is due to its ability to stand up to scrutiny in providing uniformly quality water. Many of the wastewater treatment processes developed so far span across the use of sole membranes or with the integration of other treatment technologies be it for upstream or downstream treatment depending on the quality of the wastewater and the quality of permeate being pursued. However, there has always been the problem of membrane pore blocking or fouling. This phenomenon usually lead to the reduction of permeate flux which is equivalent to productivity. These blocking phenomena are usually categorized into four mechanisms; complete blocking, intermediate blocking, standard blocking and cake filtration. In order to control particulate fouling at the design stage, as well as for monitoring during a plant operation, methods utilized in evaluating the particulate content of feed-water in predicting membrane fouling are essential. The fouling tendency, usually represented by silt density index (SDI) and modified fouling index (MFI), involve a constant-pressure membrane filtration tests, thus, the indices are calculated from the experimentally determined relationship between filtration time and cumulative permeate volumes (Boerlage et al., 2002; Huang et al., 2008). In both tests, feed-water is filtered through a 0.45 μm microfiltration membrane in a dead-end flow at constant pressure. In order to accurately measure and predict particulate fouling, it has been proposed that specific MFI be investigated with respect to specific membranes since MFI0.45 cannot represent all membrane types. This is due to the fact that principal factors such as retention of smaller particulates, proof of cake filtration, membrane pore size, surface morphology, and material must be considered in such investigations (Boerlage et al., 2002). In this study, an optimized adsorption process operation condition was applied to a high strength wastewater (final discharge effluent of the palm oil mill) to reduce the strength of the wastewater and cut down its fouling potential. Fouling mechanism on microfiltration membranes after the upstream adsorption process was characterized at different TMPs, and the results were analysed in suggesting the sustainability of the membrane productivity and cleaning procedure. The results of the study could be applied to any feedwater of similar physicochemical make up.MethodsSubsequent to an upstream adsorption process, explained elsewhere (Amosa, 2015; Amosa et al., 2015a; Amosa et al., 2015b), with the aim of reducing the blocking tendency of the industrial effluent, a laboratory-based bench scale system using a cross-flow membrane filtration process was operated. The system was equipped with two polyethersulfone (PESU) microfiltration membranes of 0.1 and 0.2 μm pores, and operated at constant transmembrane pressures (TMP) of 40, 80 and 120 kPa similar to previous reports (Springer et al., 2013). Permeate volume V at varying filtration time t data were recorded at each TMP, and the flux-time plots were used to evaluate the fouling propensities of the feed-water. The fouling mechanism of the feed on the membrane was further evaluated using the Hermia's revised blocking filtration models (Hermia, 1982) for complete, standard, intermediate and cake filtration as respectively represented in Eq. 1.0, 2.0, 3.0, and 4.0 were applied in describing and quantifying the blocking mechanisms that controls the membrane filtration at each TMPs. [1.0] [2.0] [3.0] [4.0] where Ac, B, Ai and C represent respective model constants, while J is the flux (Iritani, 2013).Results and DiscussionFigure 1. Cake filtration model fitted to the 0.1 μm MF membrane filtration data at 40 kPa Fig. 1 shows the domineering cake filtration with the highest coefficient of determination (other plots shown in attached file). With this, it will be intuitive that the intermediate blocking model should be the closest in stability to that of cake filtration model from the principle, and this will serve as a confirmation for the establishment of cake layer formation in the membrane filtration. The closest R2 value after the cake filtration appeared to be that of the intermediate blocking mechanism with a value of 0.9336. This indicates that intermediate blocking had a strength of impact close to that of the cake filtration. This is because, from principle, there exist a region where the intermediate blocking plays a role between the transition phase of the complete and standard blocking, and that of the cake filtration mechanism. The intermediate blocking plot suggests that the transition phase is between 12 and 36 minutes of filtration time which serves as the best straight line of the plot. The complete and standard blocking models are expected to be the dominant mechanism at the onset of the filtration experiment. It is evident from their plots that the two mechanisms dominated the onset of the filtration as they both exhibited their somewhat best straight lines between 0.3-1.2 L, and 1.4-2 L of filtered volumes. This can also be observed from flux-time plot for 0.1 μm MF membrane in Fig. 1. These results followed the cake filtration mechanism as reported in earlier filtration modelling investigations (Boerlage et al., 2003; Boerlage et al., 2002). Table 2 shows the stability of the 0.1 μm MF membrane at various TMPs assessed by the determination of coefficients (R2) of the filtration models. Table 2. Fitting of filtration models to 0.1 μm MF membrane TMP (kPa) R2 of Filtration models Complete Blocking Standard Blocking Intermediate Blocking Cake Filtration 40 0.8357 0.8864 0.9336 0.9835 80 0.7521 0.8022 0.8676 0.9194 120 0.8032 0.8466 0.8967 0.9388 Fig. 2. Cake filtration model fitted to the 0.2 μm MF membrane filtration data at 40 kPa Table 3 below shows the results of filtration models as fitted to the filtration experiments performed using the 0.2 μm MF membrane. Table 3. Fitting of filtration models to 0.2 μm MF membrane TMP (kPa) R2 of Filtration models Complete Blocking Standard Blocking Intermediate Blocking Cake Filtration 40 0.6801 0.7537 0.8605 0.9167 80 0.5578 0.6346 0.7943 0.8388 120 0.561 0.6746 0.886 0.909 Summarily from Tables 2 and 3, it was observed that the operation at TMP of 40 kPa gave the best fitting models overall, and it also showed that cake filtration was dominant in the mechanism describing the filtration process with highest R2 values of 0.9835 and 0.9167 for 0.1 and 0.2 μm MF membranes, respectively.ConclusionA general model of cross-flow microfiltration treatment of final discharge of palm oil mill was successfully studied to elucidate the fundamental mechanisms involved in flux decline and fouling of the membrane. The cake deposition resulting from particulates aggregation accounted for the major flux decline. The cake filtration model dominated all other fouling mechanisms in terms of R2 values for both MF membranes and this indicates that the fouling involved did not affect the pore structure of the membrane. Both MF membranes were much stable at the lowest TMP of 40 kPa which amounts to lower energy consumption of the process. However, the 0.1 μm MF membrane exhibited higher stability in terms of its higher R2 value of 0.9835 as against 0.2 μm MF with a R2 value of 0.9167. Furthermore, with cake layer formation, it could be predicted that steady state filtration will be sustainably attained at longer filtration times without complete blocking. Also, fouling due to cake layer formation is reversible, this gives an idea of cleaning methods that may be necessary during process design. This data could be utilized for upscaling design in predicting the fouling behaviour of such effluents when subjected to microfiltration process.ReferencesAmosa, M.K., 2015. Process optimization of manganese and H2S removals from palm oil mill effluent (POME) using enhanced empty fruit bunch (EFB)-based powdered activated carbon (PAC) produced from pyrolysis. Environmental Nanotechnology, Monitoring & Management In press.Amosa, M.K., Jami, M.S., Alkhatib, M.F.R., 2015a. Electrostatic Biosorption of COD, Mn and H2S on EFB-Based Activated Carbon Produced through Steam Pyrolysis: An Analysis Based on Surface Chemistry, Equilibria and Kinetics. Waste Biomass Valor, 1-16.Amosa, M.K., Jami, M.S., Alkhatib, M.F.R., Jimat, D.N., Muyibi, S.A., 2015b. A Two-Step Optimization and Statistical Analysis of COD Reduction from Biotreated POME Using Empty Fruit Bunch-Based Activated Carbon Produced from Pyrolysis. Water Qual Expo Health 7, 603-616.Boerlage, S.F., Kennedy, M.D., Aniye, M.P., Abogrean, E., Tarawneh, Z.S., Schippers, J.C., 2003. The MFI-UF as a water quality test and monitor. J. Membr. Sci. 211, 271-289.Boerlage, S.F., Kennedy, M.D., Dickson, M.R., El-Hodali, D.E., Schippers, J.C., 2002. The modified fouling index using ultrafiltration membranes (MFI-UF): characterisation, filtration mechanisms and proposed reference membrane. J. Membr. Sci. 197, 1-21.Hermia, J., 1982. Constant pressure blocking filtration law application to powder-law non-Newtonian fluid. Trans. Inst. Chem. Eng. 60, 183–187.Huang, H., Young, T.A., Jacangelo, J.G., 2008. Unified membrane fouling index for low pressure membrane filtration of natural waters: Principles and methodology. Environ. Sci. Technol. 42, 714-720.Iritani, E., 2013. A Review on Modeling of Pore-Blocking Behaviors of Membranes During Pressurized Membrane Filtration. Drying Technol. 31, 146-162.Springer, F., Laborie, S., Guigui, C., 2013. Removal of SiO2 nanoparticles from industry wastewaters and subsurface waters by ultrafiltration: Investigation of process efficiency, deposit properties and fouling mechanism. Sep. Purif. Technol. 108, 6-14.

Electric field-assisted sedimentation, also called electrokinetic or electroforced sedimentation, is a technology in which electrokinetic effects are utilised to realise an improved solid-liquid separation. Electrokinetic sedimentation practical industrial applications have been limited to the areas such as soil mechanics, civil engineering and the ceramics industry. The aim of this paper is to provide an outline of engineering applications for electrokinetic sedimentation with a focus on the theoretical analysis of electrokinetic sedimentation. In addition, various empirical research results addressing the effects of process parameters on the electrokinetic sedimentation are reviewed. It is hoped that this review would provide relevant information to contemporary researchers who are active in the field of various solid-liquid separation in general and electrokineticsedimentation in particular.

Cadmium (Cd[Formula: see text]) is one of the toxic heavy metals that is frequently used in many industrial products. The wastewater from these industries and their products contains residual cadmium that are difficult to be removed economically from the effluent. Carbon nanotubes (CNTs) were synthesized in several batches and tested for their removal efficacy with regards to cadmium removal from synthetic wastewater. Fixed catalyst chemical vapor deposition (FCCVD) reactor system was fabricated in the laboratory for the synthesis of CNTs on the powdered activated carbons (PACs). The PACs were impregnated with Fe[Formula: see text] catalysts, and growth parameters such as the reaction time, gas flow rates and reaction temperature were optimized. The sorption capacity of the raw CNT–PAC was not satisfactory until the sorbents were functionalized which eventually led to high adsorption capacities. The surface properties of CNT–PAC were modified by oxidative functionalization using two different methods: sonication with KMnO4 and refluxing with HNO3 at 140[Formula: see text]C. KMnO4-treated CNT–PAC exhibited the highest sorption capacity for cadmium uptake which increased from 4.77[Formula: see text]mg/g (untreated CNT–PAC) to 11.16[Formula: see text]mg/g; resulting in Cd[Formula: see text] removal efficiency from 38.87% to 98.35%.

Sustainability of a membrane process depends on many factors of which fouling mitigation is the most central. Because membrane fouling phenomenon is very complex, extent of fouling potential of a feedwater with respect to a membrane has to be identified right from the design stage. This will acquaint engineers with the proper fouling mitigation measures during operation. This study presents a preliminary fouling data from the ultrafiltration of biotreated palm oil mill effluent (POME) after an upstream adsorption process. The flux decline is studied in a typical constant-pressure experiments with a cross-flow ultrafiltration of biotreated POME through Sartocon® polyethersulfone membranes (MWCOs 1, 5 and 10 kDa) at applied pressures of 40, 80 and 120 kPa. Results are examined, within the frame of the common blocking mechanisms and it was found that the blocking index η decreased from 2 to 0. Pore blocking phenomenon was successively observed from complete blocking (η = 2) down to cake filtration (η = 0), and the early blockage of the pores and a formation of a cake resulted in a limiting cake height. Thus, cake filtration could be best used to explain the fouling mechanisms of biotreated POME on the ultrafiltration membranes based on the R 2 values at all applied pressures. This demonstrates that the fouling was as a result of gradual reversible cake deposition which could easily be removed by less onerous cleaning methods. In addition, it could be concluded that the upstream adsorption reduced the particulate deposition on the membrane surface.