Ng Choon Aun

Polishing of treated palm oil mill effluent (POME) from ponding system by electrocoagulation process

As the ponding system used to treat palm oil mill effluent (POME) frequently fails to satisfy the discharge standard in Malaysia, the present study aimed to resolve this problem using an optimized electrocoagulation process. Thus, a central composite design (CCD) module in response surface methodology was employed to optimize the interactions of process variables, namely current density, contact time and initial pH targeted on maximum removal of chemical oxygen demand (COD), colour and turbidity with satisfactory pH of discharge POME. The batch study was initially designed by CCD and statistical models of responses were subsequently derived to indicate the significant terms of interactive process variables. All models were verified by analysis of variance showing model significances with Prob > F < 0.01. The optimum performance was obtained at the current density of 56 mA/cm(2), contact time of 65 min and initial pH of 4.5, rendering complete removal of colour and turbidity with COD removal of 75.4%. The pH of post-treated POME of 7.6 was achieved, which is suitable for direct discharge. These predicted outputs were subsequently confirmed by insignificant standard deviation readings between predicted and actual values. This optimum condition also permitted the simultaneous removal of NH3-N, and various metal ions, signifying the superiority of the electrocoagulation process optimized by CCD.

Sequential treatment for landfill leachate by applying coagulation-adsorption process

Abstract Landfill leachate has always been the most problematic factor in municipal solid waste management. Leachate generated from landfills generally contains high amount of organic and inorganic compounds that might cause pollution to water resources. In the current study, sequential treatment of landfill leachate using coagulation–flocculations a pretreatment process followed by adsorption process was used to treat chemical oxygen demand (COD), ammonical nitrogen (NH3-N) and color from raw landfill leachate. Coagulation–flocculation process was examined using alum and ferric chloride. The optimum working pH for the tested coagulants was 5 and FeCl3 showed higher removal efficiency for landfill leachate than alum. The pretreated leachate was further treated via two types of adsorbents i.e., powdered activated carbon (PAC) and zeolite. The optimum experimental conditions for PAC and zeolite adsorptions were found to be 40 g/L at 30 min and 80 g/L at 120 min, respectively. Scanning electron microscope and Fourier transform infrared spectroscopy tests were conducted to examine the surface morphology and chemical properties of the adsorbents. The results showed that the Freundlich isotherm was best fitted for PAC adsorption while Langmuir isotherm model showed good conformity for zeolite adsorption. Besides, pseudo-second order model was found to be the best fitted kinetic model for both PAC and zeolite adsorption where the R2 was closed to unity for all parameters. On balance, FeCl3 coagulation-PAC adsorption has shown higher removal efficiency for color, COD, and NH3-N as compared to FeCl3 coagulation-zeolite adsorption.

Evaluation of Energy Cost Saving and Pollutants Emission Reduction for Solar Water Heater Development in Malaysia

A potential solution to curb the environmental problems is the utilization of renewable energy, including solar energy. Malaysia has abundant solar energy resources throughout the year, promises the highest beneficial in using solar energy for technology development such as solar water heater (SWH). However, peoples in Malaysia are not aware of SWH’s advantages due to the high initial installation cost of SWH. Thus, this study presents financial evaluation of SWH in Malaysia which takes into account of the cost saving and pollution prevention by SWH instead of electrical water heater (EWT). The benefit of SWH was analysed based on annual effective solar radiation. From the analysis, the utilization of a SWH can save up to RM 708.3 of energy cost per year and avoid 1583 kg CO2, 12 kg SO2 and 5 kg NOx emissions per year.

Segmentation and quantification of activated sludge floes for wastewater treatment

Activated sludge process is commonly used in wastewater treatment plants to process domestic or industrial effluent. The main objects of interest in the activated sludge systems are floes and filamentous organisms. The proper settling of the sludge floes in the activated sludge wastewater treatment process is crucial to the normal functioning of the system. In this paper image processing techniques are used to segment and detect activated sludge floes in microscopic images of activated sludge. This can be helpful in the study of the morphology of floes and their quantification. In this paper, Otsu thresholding, k-means and fuzzy c-means segmentation techniques are used to segment and detect floes in microscopic images of activated sludge. The performance of the segmentation techniques is assessed for activated sludge images at different microscopic magnifications using global consistency error (GCE. Ground truth images are used to benchmark the accuracy of segmentation algorithms. Otsu thresholding method performed better segmentation in terms GCE. But the performance of segmentation deteriorates at higher magnifications. The quantification of floes also provides a means for assessing the segmentation performance of different algorithms. Otsu thresholding has better quantification performance as compared to fuzzy c-means and k-means, with some apparent exceptions caused by imperfect segmentation of images at 40 times magnification.

Applicability of anaerobic membrane bioreactors for landfill leachate treatment: Review and opportunity

Sanitary landfilling is nowadays the most common way to eliminate municipal solid wastes (MSW). The resulted landfill leachate is a highly contaminated liquid. Even small quantities of this high-strength leachate can cause serious damage to surface and ground water receptors. Thus, these leachates must be appropriately treated before being discharged into the environment. In the last years, anaerobic membrane bioreactor (AnMBR) technology is being considered as a very attractive alternative for leachate treatment due to the significant advantages. In the last decade, many studies have been conducted in which various types of anaerobic reactors were used in combination with membranes. This paper is a review of the potential of anaerobic membrane bioreactor technology for municipal landfill leachate treatment. A critical review in AnMBR performance interesting landfill leachate in lab scale is also done. In addition, the review discusses the impact of the various factors on both biological and filtration performances of anaerobic membrane bioreactors.

Iterative region based Otsu thresholding of bright-field microscopic images of activated sludge

Image processing and analysis is a potential alternative monitoring tool for biodegradation in activated sludge wastewater treatment process. Accuracy of image analysis based predictive models depends on the quality of the segmentation of the microbial aggregates in microscopic images of activated sludge. The segmentation of the images is hindered by irregular illumination and properties of the microbial aggregates such as varying opaqueness and size. In this paper, an iterative region based Otsu thresholding is proposed for the bright field microscopic images of activated sludge. The suggested approach takes not only the statistics of grayscale intensities into account but also the regional distribution of the illumination noise. The proposed algorithm is compared with state-of-the-art Otsu, iterative Otsu and local Otsu segmentation techniques. The performance of the algorithms is assessed using accuracy, Rand index (RI) and variation of information (VI). The proposed algorithm exhibited better performance in terms of all the metrics with accuracy 0.9854, RI 0.9721 and VI 0.2141.