Mohammed Saedi Jami

Application of Electroosmosis for Sludge Dewatering—A Review

This work aims at providing an outline of engineering applications for electroosmosis, especially for sludge dewatering. A review of the theoretical analysis of electroosmotic dewatering is presented. The equations representing electroosmotic flow through porous media are initially discussed. Consolidation theory, which describes the progress of dewatering, is then described. In addition, various empirical research results addressing the effects of operational conditions and conditioning of sludge on both energy consumption and final water content of the sludge are reviewed. It is anticipated that this review will provide useful information to researchers pursuing solid–liquid separation of difficult-to-dewater materials such as sludge.

Evaluation of solvent system for the enzymatic synthesis of ethanol-based biodiesel from sludge palm oil (SPO).

A green technology of biodiesel production focuses on the use of enzymes as the catalyst. In enzymatic biodiesel synthesis, suitable solvent system is very essential to reduce the inhibition effects of the solvent to the enzymes. This study produced ethanol-based biodiesel from a low-cost sludge palm oil (SPO) using locally-produced Candida cylindracea lipase from fermentation of palm oil mill effluent (POME) based medium. The optimum levels of ethanol-to-SPO molar ratio and enzyme loading were found to be 4:1 and 10 U/25 g of SPO respectively with 54.4% w/w SPO yield of biodiesel and 21.7% conversion of free fatty acid (FFA) into biodiesel. Addition of tert-butanol at 2:1 tert-butanol-to-SPO molar ratio into the ethanol-solvent system increased the yield of biodiesel to 71.6% w/w SPO and conversion of FFA into biodiesel to 28.8%. The SPO and ethanol have promising potential for the production of renewable biodiesel using enzymatic-catalyzed esterification and transesterification.

Recombinant bromelain production in Escherichia coli: process optimization in shake flask culture by response surface methodology.

Bromelain, a cysteine protease with various therapeutic and industrial applications, was expressed in Escherichia coli, BL21-AI clone, under different cultivation conditions (post-induction temperature, L-arabinose concentration and post-induction period). The optimized conditions by response surface methodology using face centered central composite design were 0.2% (w/v) L-arabinose, 8 hr and 25°C. The analysis of variance coupled with larger value of R2 (0.989) showed that the quadratic model used for the prediction was highly significant (p < 0.05). Under the optimized conditions, the model produced bromelain activity of 9.2 U/mg while validation experiments gave bromelain activity of 9.6 ± 0.02 U/mg at 0.15% (w/v) L-arabinose, 8 hr and 27°C. This study had innovatively developed cultivation conditions for better production of recombinant bromelain in shake flask culture.

Analysis of Combined Electroosmotic Dewatering and Mechanical Expression Operation for Enhancement of Dewatering

This article presents an efficient approach for the analysis of combined electroosmotic dewatering (EOD) and mechanical expression (ME) using the Terzaghi-Voigt combined model by considering creep deformation of the material. The EOD-ME process enhances dewatering because it combines the advantage of electroosmosis and mechanical dewatering, resulting in reduced void ratio compared to individual operation. The basic differential equation based on the model is solved analytically by assuming that both an electroosmotic pressure gradient E pg and a modified consolidation coefficient C e of the material are constant, resulting in the equation of solid compressive pressure in the material as a function of time and position. The analysis also leads to the equation of the average consolidation ratio U c, which is a measure of the progress of dewatering; this equation can describe well the empirical results under various conditions. The proposed approach can clearly explain the relationship of the driving forces of individual mode of operation. The large water content of semisolid bentonite–water mixture can effectively be reduced by the EOD-ME combined operation analyzed in this research.

Filtration Behaviors in Constant Rate Microfiltration with Cyclic Backwashing of Coagulated Sewage Secondary Effluent

The constant rate microfiltration characteristics of sewage secondary effluent pretreated with polyaluminum chloride (PACl) have been investigated. In order to reduce membrane fouling, the periodic operation of constant rate microfiltration and backwashing cycles was conducted using the fully automated experimental apparatus with the monolithic ceramic membrane module. As filtration proceeded, cake formation occurred on the membrane surface, causing an increase in pressure drop. Backwashing could reduce the flow resistance that resulted from the formation of the filter cake. However, the initial pressure drop seemed to increase after each backwashing due to the irreversible pore blocking of the membrane. Based on the intermediate blocking law, a mathematical model has been developed to describe the pore blocking behavior. Using the model in combination with the filtration rate equation for the compressible cake, the energy consumption has been evaluated for the whole process. The experimental results were in good agreement with those calculated from the theoretical model. Optimum operational conditions for an energy efficient process were suggested based on analytical results. The reclaimed water is found to be free from microorganisms and can be reused in applications such as toilet flushing or car washing.

Turbidity and suspended solids removal from high-strength wastewater using high surface area adsorbent: Mechanistic pathway and statistical analysis

Abstract In this study, the potential of an improved empty fruit bunch-based powdered activated carbon (PAC) with high surface area was employed in removing suspended solids and turbidity from a high-strength wastewater. Also, the effects of operating parameters, such as PAC dosage, contact time and mixing speed on sorption trends of the two pollutants from the wastewater—biotreated palm oil mill effluent using a full factorial experimental design was investigated. Adsorption efficiency of 89.1 and 91.4% were observed for suspended solids and turbidity, respectively, at the operating condition of 3.5 g PAC dosage, 45 min contact time and 150 rpm mixing speed. The analysis of variance also revealed that the actual and model predicted values were in agreement with R 2 values of 0.9949 and 0.9991 for suspended solids and turbidity, respectively. The three operating factors had similar significance on the sorption of both pollutants with an increasing sequence of significance: contact time < mixing speed < PAC dosage. This is indicative of their similar mechanistic pathway and response trends to the adsorption process. The Freundlich and pseudo-second-order models also predicted the experimental data in describing the adsorption behaviour with R 2 values of 0.9057 and 0.9998.

Effect of Operating Parameters on the Effectiveness of Electric Field-Enhanced Separations

The purpose of this work is to summarize our latest research results about constant-current electroosmotic dewatering (EOD). The Terzaghi-Voigt combined model is used for the analysis of EOD of various solid-liquid systems by considering the creep deformation of the material. Bentonite clay, KC-flock, zinc oxide, and some of their mixtures are used as experimental materials. It is assumed that the electroosmotic pressure gradient E pg and modified consolidation coefficient C e of the materials are constant. The relation between the ratio of creep deformation to total deformation B and the modified consolidation coefficient C e is determined and compared with previous observations for the case of mechanical expression. The effectiveness of dewatering is described depending on operating parameters such as preconsolidation pressure, material composition, electric current density, and total solid volume per unit cross-sectional area. The model is verified by comparing the calculations with experimental data.

Enzymatic biodiesel production from sludge palm oil (SPO) using locally produced Candida cylindracea lipase

Biodiesel is a non-toxic, renewable and environmental friendly fuel. This study involved the production of biodiesel from sludge palm oil (SPO), a low-cost waste oil via enzymatic catalysis. The enzyme catalyst was a Candida cylindracea lipase, locally-produced using palm oil mill effluent as the low cost based medium. The results in solvent system for biodiesel production showed that ethanol gave higher yield of biodiesel as compared to methanol. One-factor-at-a time (OFAT) method was applied to investigate several factors for enzymatic biodiesel production. The optimum levels of ethanol-to-SPO molar ratio, enzyme loading, reaction temperature, mixing speed and reaction time were 4:1, 10 U, 40°C, 250 rpm and 24 h, respectively with maximum yield of biodiesel of 62.3% (w/w SPO). The SPO had a promising potential for enzymatic biodiesel production using locally-produced lipase.

Optimization of Manganese Reduction in Biotreated POME onto 3A Molecular Sieve and Clinoptilolite Zeolites.

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.

Studies on pore blocking mechanism and technical feasibility of a hybrid PAC-MF process for reclamation of irrigation water from biotreated POME

ABSTRACT 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.