Optimization of Water Treatment Parameters using Processed Moringa oleifera As a Natural Coagulant for Low Turbidity Water

Moringa oleifera is a natural coagulant which can be used for water treatment in tropical developing countries. This study presents the results of production of natural coagulant from processed Moringa oleifera with simple technique (oil extraction, salt extraction, and microfiltration with 0.2 μm). The optimization study on physical factors was carried out for coagulation-flocculation process. Low initial turbidity water samples (synthetic and river water) were used with turbidity less than 50 Nephelometric Turbidity Units (NTU). The response surface methodology (RSM) was used, and the analysis of variance (ANOVA) was performed to validate the developed regression model. The residual turbidity obtained was 4.514 NTU for synthetic water and 1.598 NTU for river water by applying the optimum conditions of 40 rpm (low speed), mixing time of 41 minutes, and Moringa oleifera dosage of 0.75 mg/L

3-D CFD transient simulation of transesterification in stirred tank reactor

A transient CFD simulation was successfully carried out for waste cooking oil (WCO)transesterification in a stirred tank reactor (STR). In this work, a multi-species reaction model was simplified to simulate the reactive flow in an STR using in a multiple reference frame (MRF)approach. Average velocity fields in the STR, by a mixed flow impeller were taken using a 2-D PIV technique to calculate the turbulence and dissipation energy statistically for the numerical model. The thermo-physical properties of the reacting species were incorporated as user defined function (UDF) to implement the reaction in ANSYS FluentTM. Reaction/ flow coupling was achieved using the eddy dissipation model. The biodiesel yield predictions were fairly comparable with the experimental data. Time steps of the model are important aspects that primarily affect the solutions of the simulation

Modification of CDV reactor for carbon nanomaterialns production

Chemical vapour deposition (CVD) reactor is one of the processes commonly used for carbon nanomaterial (CNM) production. This method is economical and provides high yield of good quality CNM. However, improvement of the CVD reactor system was necessary due to its long time requirement to complete each batch of production. A two-stage CVD was designed, locally fabricated and modified to overcome the limitations. Improvements included multistage system, which can be used to perform different processes such as floating catalyst reaction, fixed catalyst process, calcination, reduction and oxidation processes. A cooling system was added to reduce the production time. The system was further modified to increase the adsorption capacity of the products. The time requirement for one batch of run was reduced from 8 hours to 3 hours by improving the system

Kinetics of cadmium adsorption by CNTs grown on PACs

Isotherms and kinetic models are useful tool for the investigation of adsorption process. Carbon nanotubes (CNTs) grown on powdered activated carbons (PACs) was used as novel adsorbent. Two isotherms and three kinetic models were studied for the removal of cadmium from water. The isotherms were Langmuir and Freundlich and the kinetic models were pseudo first order, pseudo second order and intraparticle diffusion models. Langmuir constants were qm = 69.759 mg/g, Kl = 0.223 and R2 = 0.924. The adsorption process was found more likely to follow Freundlich model with R2 value of 0.961, Kf of 9.215 and n of 3.015. Based on the kinetics study, the pseudo second order was the best fit with R2 of 0.996 and model constants were qe = 34.29 (mg/g) and K2 = 0.0013 (g/mg.min). Coefficients for the pseudo first order were qe= 21.145 (mg/g) and K1= 0.09 (min-1) with R2 of 0.936. The intraparticle kinetic model exhibited R2 value of 0.812 with Kd = 1.295 (g/mg.min0.5). CNTs after oxidative functionalization with KMnO4 were observed to be an efficient adsorbent for Cd2+ removal from water

Optimization study on sewage sludge conditioning using Moringa oleifera seeds

Disposal of sewage sludge is a main problem faced by local municipalities in Malaysia. Sludge conditioned with chemical polymer often termed as undesirable use for land application. However, using natural polymer will help to reduce the impact of this problem. In this study, optimization using Moringa oleifera seeds as a natural polymer in sewage sludge conditioning is highlighted. An earlier sludge conditioning using jar test apparatus was conducted using Moringa oleifera seeds in three different forms; dry powder, distilled water extracted and salt extracted (1 N NaCl). Results from the study indicate that Moringa oleifera in distilled water extracted form shows the most optimum reduction in Capillary Suction Time (CST) value. Optimization of three important factors namely mixing speed, mixing duration and Moringa oleifera dosage for distilled water extracted form was done using Design of Experiments (DOE). Optimum values for the selected factors were obtained using Box-Behnken design, Response Surface Design Method (RSM). There was a total of seven set of optimized solutions produced. The best solution generated showed lowest CST and Specific Resistance to Filtration (SRF) was obtained at 4.5 s and 1.22 x 1011 m/kg respectively. These values were obtained under the optimum conditions of mixing speed at 100 rpm, mixing duration of 1 min and Moringa oleifera dosage of 4695 mg/L. The desirability index for the optimized solution was 1.000

The effects of SRT, OLR and feed temperature on the performance of membrane bioreactor treating high strength municipal wastewater.

The effects, of sludge retention time (SRT), feed temperature (Tf) and organic loading rate (OLR) on submerged membrane bioreactor (SMBR) performance were studied using hollow fibers (nominal pore size 0.4 µm) immersed in an aeration tank. A synthetic wastewater representative of high strength municipal wastewater was used in the study. Ten experimental runs were carried out using full factorial design with three factors and three levels (low, medium and high). These levels were 25, 30 and 35 days for SRT, 20, 30 and 40°C for Tf and 1.73, 4.03 and 6.82 kg COD/m³ d for OLR. Variation of OLR, SRT and Tf affected the biomass development significantly. The higher OLR trials resulted in higher MLVSS/MLSS ratio and also higher increasing rate of MLSS (d(MLSS)/ (dt)). For the low level OLR trials MLVSS/MLSS ratio varied between 75.3 and 82.3% and d(MLSS)/(dt) from 87.5 to 297.3 mg/l.d, whereas, for the high OLR trials they varied between 80.4 and 83.7% and 1355.4-2120.1 mg/l.d respectively. For the higher OLR, a higher aeration rate was applied to fulfill the DO demand. Therefore, for the low level OLR trials, the aeration rate and the DO were varied from 6 to 12 m³/m² membrane area per hour and from 3.7 to 5.7 mg/l, respectively, whilst for the high OLR trials they varied from 6 to 18 m³/m² membrane area/h and from 0.9 to 4.4 mg/l respectively. The permeate COD and NH3-N under different operating conditions varied from 0 to 32 mg/l, and from 0.004 to 0.856 mg/l, respectively. The interaction effects of SRT and Tf on COD removal efficiency was found to be insignificant. Increasing OLR did not affect COD removal. The optimum removal efficiency of ammonia nitrogen for the low and high strength wastewater was obtained at operating conditions of high SRT and low Tf. The pH increased significantly in the aeration tank and the increase was well correlated with the feed pH (r² = 0.8336 for low OLR and 0.9106 for high OLR)