The refining of the crude palm oil (CPO) generates the palm oil refinery effluent (PORE). The presence of high contents of biochemical oxygen demand (BOD), chemical oxygen demand (COD), turbidity, and suspended solids (SS) in PORE encourages the determination of an effective treatment process to minimize the environmental pollution and preserve aquatic life. In the present study, a biodegradable natural polymer, namely tannin, was utilized as a coagulant to treat PORE. The coagulation experiment was conducted using a jar test apparatus. The tannin coagulation efficiency was evaluated based on the BOD, COD, turbidity, and SS removal from PORE by varying the tannin dose (50-300 mg/L), pH (pH 4-10), treatment time (15-90 min), and sedimentation time (15-90 min). It was found that the maximum removal of BOD, COD, turbidity, and SS was 97.62%, 88.89%, 93.01%, and 90.21%, respectively, at pH 6, a tannin dose of 200 mg/L, 60 min of coagulation time, and 60 min of sedimentation time. Analyses of isotherm models revealed that the Freundlich isotherm model was well fitted with the coagulation study. Kinetics studies show that the pseudo-second-order kinetics model was the well-fitted kinetics model for the BOD, COD, turbidity, and SS removal from PORE using tannin as a polymeric coagulant. The determination of thermodynamics parameters analyses revealed that BOD, COD, turbidity, and SS removal from PORE was spontaneous, exothermic, and chemical in nature. The finding of the present study shows that tannin as a natural polymeric coagulant would be utilized in PORE treatment to avoid toxic sludge generation.
Many wastewater treatment plants (WWTPs) operating in biological nitrogen removal activated sludge process in the tropics are facing the pressure of increasingly stringent effluent standards while seeking solutions to reduce the plants' energy consumption and operating cost. This study investigated the feasibility of applying low-dissolved oxygen (low-DO) nitrification and utilizing slowly-biodegradable chemical oxygen demand (sbCOD) for denitrification, which helps to reduce energy usage and operating cost in treating low soluble COD-to-nitrogen tropical wastewater. The tropical wastewater was first characterized using wastewater fractionation and respirometry batch tests. Then, a lab-scale sequencing batch reactor (SBR) was operated to evaluate the long-term stability of low-DO nitrification and utilizing sbCOD for denitrification in an anoxic-oxic (AO) process treating tropical wastewater. The wastewater fractionation experiment revealed that particulate settleable solids (PSS) in the wastewater provided slowly-biodegradable COD (sbCOD), which made up the major part (51 ± 10%) of the total COD. The PSS hydrolysis rate constant at tropical temperature (30 °C) was 2.5 times higher than that at 20 °C, suggesting that sbCOD may be utilized for denitrification. During the SBR operation, high nitrification efficiency (93 ± 6%) was attained at low-DO condition (0.9 ± 0.1 mg O2/L). Utilizing sbCOD for post-anoxic denitrification in the SBR reduced the effluent nitrate concentration. Quantitative polymerase chain reaction, 16S rRNA amplicon sequencing and fluorescence in-situ hybridization revealed that the genus Nitrospira was a dominant nitrifier. 16S rRNA amplicon sequencing result suggested that 50% of the Nitrospira-related operational taxonomic units were affiliated with comammox, which may imply that the low-DO condition and the warm wastewater promoted their growth. The nitrogen removal in a tropical AO process was enhanced by incorporating low-DO nitrification and utilizing sbCOD for post-anoxic denitrification, which contributes to an improved energy sustainability of WWTPs.
Rivers as surface water in Malaysia are recipients of effluents and wastewater and yet it is important water source for daily uses of some villagers living along the river. Endocrine disruptors such as Bisphenol A (BPA) can be found in river due to continuous discharge into it. The objectives of this research is to find out the occurrence and concentration of BPA in Sungai Langat and also to see how water quality parameters such as temperature, pH, dissolved oxygen (DO), turbidity, Total Suspended Solid (TSS), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and ammonia nitrogen (AN) affecting the concentration of BPA. 12 stations in total including upstream to downstream of Sungai Langat and also tributary of Sungai Langat. The instrument used to find out concentration of BPA is Triple Quadrupole LC/MS. The source of BPA are mainly industrial effluents and also direct domestic discharges. The water quality parameters that will affect concentration of BPA are Ammonia Nitrogen (AN), turbidity, Biochemical Oxygen Demand (BOD), Total Suspended Solid (TSS), and Chemical Oxygen Demand (COD), Dissolved Oxygen (DO). While pH and water temperature are also factors that will affect concentration of BPA but the significance is not shown in the analysis. It can be concluded that upstream of Sungai Langat has lower concentration of BPA than downstream.
Domestic wastewater has been generated massively along with rapid growth of population and economic. Biological treatment using sequencing batch reactor (SBR) augmented with palm oil fuel ash (POFA) was investigated for the first time. The performance of POFA in enhancing biological treatment of wastewater has not been tested. The porosity property of POFA can improve SBR efficiency by promoting growth of mixed liquor suspended solids (MLSS) and formation of larger flocs for settling and facilitating attachment of microorganisms and pollutants onto POFA surfaces. The properties of POFA were tested to identify morphological properties, particle size, surface area, chemical compositions. Four SBRs, namely SBR1, SBR2, SBR3 and SBR4 were provided with aeration rate of 1, 2, 3 and 4 L/min, respectively. Each reactor was augmented with different dosages of POFA. Optimum aeration rate and POFA concentration were identified by the performance of SBRs in removing chemical oxygen demand (COD), ammoniacal nitrogen (NH3-N) and colour from domestic wastewater. The results showed the most efficient COD (97.8%), NH3-N (99.4%) and colour (98.8%) removals were achieved at optimum POFA concentration of 4 g/L in SBR and aeration rate of 1 L/min. The study also found that higher aeration rate would contribute to the smaller specific size of flocs and decrease the pollutant removal efficiency.
The objective of this study was to investigate the performance of different weight of Salvinia molesta plants in biological treatment of domestic wastewater. Three treatment systems containing 280g (GS1), 140g (GS2) and 70g (GS3) of S. molesta plants were used for the phytoremediation process. Physicochemical analysis such as pH, colour, chemical oxygen demand (COD), and biological oxygen demand (BOD5) of the influent and effluent water samples were performed according to spectrophotometric methods. The outcome of the study demonstrated that the different weight of S. molesta plants played a significant role in improving the quality of the wastewater samples, in which GS1 removed 96.8% (colour), 91% (BOD5), and 82.6% (COD). While up to 88.6% (colour), 87.1% (BOD5), and 81.1% (COD) reduction was observed for GS2 treatment systems, and GS3 was efficient in removing 85.5% (colour), 86.1% (BOD5), and 68.3% (COD). Also, a pH value of 6.29-7.19, 5.97-7.07, and 6.17-7.42 was obtained from GS1, GS2 and GS3 treatment systems, respectively. Thus, the treatment system with the highest quantity of S. molesta (GS1) demonstrated better performance compared to the other two systems (GS2 and GS3). The findings of this research can be applied in addressing the goals of sustainable development through the use of green technology to reduce the threat of water pollution in natural water bodies. Perhaps existing and future water scarcity can be resolved through the use of phytoremediation technology.
Land use plays a significant role in determining the spatial patterns of water quality in the Johor River Basin (JRB), Malaysia. In the recent years, there have been several occurrences of pollution in these rivers, which has generated concerns over the long-term sustainability of the water resources in the JRB. Specifically, this water resource is a shared commodity between two states, namely, Johor state of Malaysia and Singapore, a neighbouring country adjacent to Malaysia. Prior to this study, few research on the influence of land use configuration on water quality have been conducted in Johor. In addition, it is also unclear how water quality varies under different seasonality in the presence of point sources. In this study, we investigated the influence of land use and point sources from wastewater treatment plants (WWTPs) on the water quality in the JRB. Two statistical techniques - Multivariate Linear Regression (MLR) and Redundancy Analysis (RA) were undertaken to analyse the relationships between river water quality and land use configuration, as well as point sources from WWTPs under different seasonality. Water samples were collected from 49 sites within the JRB from March to December in 2019. Results showed that influence from WWTPs on water quality was greater during the dry season and less significant during the wet season. In particular, point source was highly positively correlated with ammoniacal‑nitrogen (NH3-N). On the other hand, land use influence was greater than point source influence during the wet season. Residential and urban land use were important predictors for nutrients and organic matter (chemical oxygen demand); and forest land use were important sinks for heavy metals but a significant source of manganese.
In this study, yeast microbial fuel cells (MFCs) were established as biosensors for in-situ monitoring of dissolved oxygen (DO) levels in environmental waters, with yeast and glucose substrates acting as biocatalyst and fuel, respectively. Diverse environmental factors, such as temperature, pH and conductivity, were considered. The sensor performance was first tested with distilled water with different DO levels ranging from 0 mg/L to 8 mg/L and an external resistance of 1000 Ω. The relationship between DO and current density was non-linear (exponential). This MFC capability was further explored under different environmental conditions (pH, temperature and conductivity), and the current density produced was within the range of 0.14-34.88 mA/m2, which increased with elevated DO concentration. The resulting regression was y = 1.3051e0.3548x, with a regression coefficient (R2) = 0.71, indicating that the MFC-based DO meter was susceptible to interference. When used in environmental water samples, DO measurements using MFC resulted in errors ranging from 6.25 % to 15.15 % when compared with commercial DO meters. The simple yeast-based MFC sensors demonstrate promising prospects for future monitoring in a variety of areas, including developing countries and remote locations.
Shaped-controlled ZnO architectures including spherical, rod, rice-like and flower-like were fabricated via a reflux method in which the morphology, crystallinity, functional group and optical properties were tailored under different pH values in the precursor solution. The photoactivities of the prepared ZnO were evaluated under UV irradiation and the findings implied that the flower-like ZnO synthesized at pH 12 displayed superior activities on palm oil mil effluent degradation than those of other structures. The photocatalytic enhancement of flower-like ZnO was ascribed to its unique architecture, good crystallinity and superior optical properties. The flower-like ZnO with excellent photocatalytic performance have been confirmed by formation of hydroxyl radicals using a terephthalic acid-photoluminescence test. There was an optimal photocatalyst amount of 1.0 g/L, at which a maximum chemical oxygen demand removal of palm oil mill effluent was achieved under exposure of UV light. The phytotoxicity experiment via mung beans demonstrated a decrease in phytotoxicity.
Land development, especially construction works, increase storm water volumes and pollution loads into rivers and lakes. The temporary drainage system at construction sites, particularly during the construction stage discharges a large amount of pollutants that can damage the aquatic system of the receiving water bodies. The potential of vegetative swale to alleviate this problem was evaluated. The size of the constructed vegetative swale was 7cm deep, 400cm long and 15cm wide at the bottom, and 17cm wide at the top. The experiment was conducted batch wise by filling the storage tank with the run-off water from the construction site. The water was allowed to flow through a pipe into the retention basin to maintain uniform flow before it entered the swale. The study showed that the run-off infiltrated through the soil at a rate of 489.6 mm/hr. Samples of surface run-off and infiltration water were collected at the end and the bottom of the swale. The results indicate that chemical oxygen demand (COD), total suspended solid (TSS), turbidity, iron and zinc were reduced by 85.4%, 80.8%, 36.4%, 52.8% and 96.0%, respectively, by surface flow and 91.1%, 98.8%, 58.2% 55.5% and 98.1%, respectively, by infiltration. Removal of nitrate and phosphorus by the planted vegetation was 69.4% and 21.1%, respectively, by infiltration. However, nutrient removal by surface flow was negligible. In conclusion, the vegetative swale was able to improve the water quality of the storm water run-off from the construction site from Class V to Class III, according to the Interim National Water Quality Standards for Malaysia.
This study demonstrated the potential of single chamber up-flow membrane-less microbial fuel cell (UFML-MFC) in wastewater treatment and power generation. The purpose of this study was to evaluate and enhance the performance under different operational conditions which affect the chemical oxygen demand (COD) reduction and power generation, including the increase of KCl concentration (MFC1) and COD concentration (MFC2). The results showed that the increase of KCl concentration is an important factor in up-flow membrane-less MFC to enhance the ease of electron transfer from anode to cathode. The increase of COD concentration in MFC2 could led to the drop of voltage output due to the prompt of biofilm growth in MFC2 cathode which could increase the internal resistance. It also showed that the COD concentration is a vital issue in up-flow membrane-less MFC. Despite the COD reduction was up to 96%, the power output remained constrained.
The performance of modified anaerobic inclining-baffled reactor (MAI-BR) treating recycled paper mill effluent (RPME) was investigated by varying the influent chemical oxygen demand (CODin) concentration from 1000 to 4000 mg/L, and the hydraulic retention time (HRT) from 3 to 1 day, corresponding to an organic loading rate increase from 0.33 to 4 g COD/L day. Throughout 126 days of operation, a maximum removal efficiency of up to 96% of chemical oxygen demand (COD) and 99% of biological oxygen demand, methane (CH4) yield of 0.259 L CH4/g COD, and a stable effluent pH of 6.5 were achieved. Furthermore, the compartmental performance showed that most of the organic substrates were removed in the initial two compartments, resulting in low pH and alkalinity levels and a high concentration of volatile fatty acids. Overall, the results showed that the MAI-BR successfully treated RPME, and the performance was affected by the variation of HRT more than the CODin.
Although landfilling is still the most suitable method for solid waste disposal, generation of large quantity of leachate is still considered as one of the main environmental problem. Efficient treatment of leachate is required prior to final discharge. Persulfate (S2O82-) recently used for leachate oxidation, the oxidation potential of persulfate can be improved by activate and initiate sulfate radical. The current data aimed to evaluate the performance of utilizing Al2SO4 reagent for activation of persulfate to treat landfill leachate. The data on chemical oxygen demand (COD), color, and NH3-H removals at different setting of the persulfate, Al2SO4 dosages, pH, and reaction time were collected using a central composite design (CCD) were measured to identify the optimum operating conditions. A total of 30 experiments were performed, the optimum conditions for S2O82-/Al2SO4 oxidation process was obtained. Quadratic models for chemical oxygen demand (COD), color, and NH3-H removals were significant with p-value
Microbial fuel cells (MFCs) are considered as promising technology to achieve simultaneous wastewater treatment and electricity generation. However, operational and technological developments are still required to make it as a sustainable technology. In the present study, response surface methodology (RSM) was used to evaluate the effects of substrate concentration, co-culture composition, pH and time on the performance of co-culture (Klebsiella variicola and Pseudomonas aeruginosa) inoculated double chamber MFC. From the statistical analysis, it can be seen that the performance of MFC was not influenced by the interaction between the initial COD and time, pH and time, pH and initial COD, time and initial COD. However, the interaction between the inoculum composition and time, pH and the inoculum composition, initial COD and inoculum composition significantly influenced the performance of MFC. Based on the RSM results, best performance (power density and COD removal efficiency) was obtained when the inoculum composition, initial COD, pH and time were about 1:1, 26.690 mg/L, 7.21 and 15.50 days, respectively. The predictions from the model were in close agreement with the experimental results suggesting that the proposed model could adequately represent the actual relationships between the independent variables generating electricity and the COD removal efficiency.
The Cassava starch manufacturing wastewater (CSW) was used as a substrate to produce polyhydroxybutyrate (PHB) by Cupriavidus sp. KKU38. The acidogenic fermentation process of CSW was first conducted to obtain volatile fatty acids (VFAs), which are more efficient in PHB production than raw CSW. The effect on substrate concentration and nutrients, i.e. nitrogen and phosphorus concentrations, by means of chemical oxygen demand: nitrogen: phosphorus ratio (COD:N:P ratio) variation was investigated. The results indicated that PHB production from fermented CSW by Cupriavidus sp. KKU38 was optimized at the soluble COD:N:P ratio of 100:0.5:11. This ratio gave the maximum PHB content and yield of 85.53% and 0.31 g PHB/g COD consumed, respectively. By using the proposed PHB production process, the potential to produce 0.19 kg of PHB from 1.0 kg of soluble chemical oxygen demand (sCOD) contained in CSW was exhibited. The relatively high COD removal efficiency of 73.82% at the optimal condition could be achieved, which demonstrated the concept of water quality improvements alongside the production of the value-added by-product, PHB.
This paper presents the results for surface water quality parameters measured in the Setiu Wetland, on the east coast of Malaysia, which feeds into the southern part of the South China Sea. There are no previous studies dealing with the seasonal and spatial variation of water quality in this area, despite numerous anthropogenic inputs into this ecologically and economically important wetland. The parameters measured were salinity, temperature, dissolved oxygen (DO), pH, biological oxygen demand (BOD) and total suspended solids (TSS). These parameters were sampled monthly from October 2009 to September 2010, during both the wet and dry seasons, at ten sampling stations distributed throughout the area. The physical water quality parameters were measured in situ whilst TSS and BOD were determined using the standard methods. A deterioration of water quality in the Setiu Wetland was observed in areas near agriculture and aquaculture activities. This was expected to be as a result of the use of fertilisers, waste from fish farm food and the waste products of aquaculture. The parameters measured showed lower mean values of surface salinity, temperature, DO, pH and TSS during the wet season relative to the dry season. In contrast, the concentration of BOD was high during the wet season and lowest in the dry season. Results obtained from this study clearly showed the surface physical water quality for the Setiu Wetland was highly influenced by anthropogenic activities and seasonal variation. Therefore, both factors must be considered to move towards proper management of this wetland.
Five years of data from 2001 until 2006 of warm unstratified shallow, oligotrophic to mesothropic tropical Putrajaya Lake, Malaysia were used to study pattern discovery and forecasting of the diatom abundance using supervised and unsupervised artificial neural networks. Recurrent artificial neural network (RANN) was used for the supervised artificial neural network and Kohonen Self Organizing Feature Maps (SOM) was used for unsupervised artificial neural network. RANN was applied for forecasting of diatom abundance. The RANN performance was measured in terms of root mean square error (RMSE) and the value reported was 29.12 cell/mL. Classification and clustering by SOM and sensitivity analysis from the RANN were used to reveal the relationship among water temperature, pH, nitrate nitrogen (NO3-N) concentration, chemical oxygen demand (COD) concentration and diatom abundance. The results indicated that the combination of supervised and unsupervised artificial neural network is important not only for forecasting algae abundance but also in reasoning and understanding ecological relationships. This in return will assist in better management of lake water quality.
Setiu Wetland is located in the southern part of South China Sea, Malaysia. This wetland has diverse ecosystems that represent a vast array of biological diversity and abundance in utilizable natural resources. However, there are large scales of aquaculture activities within and nearby the wetland which could threaten the ecosystems of this area. Thus, the main goal of the study was to assess the impact of these activities through the measurement of physico-chemical water quality parameters and then compare this to a previous study carried out in the same study area. The parameters (salinity, temperature, pH, dissolved oxygen, biological oxygen demand and total suspended solids) were monitored monthly at the surface water from July to October 2008. The results showed that the impact of aquaculture activities on the water quality in the area with dissolved oxygen and total suspended solids concentrations were considerably lower than those observed previously. With respect to the Malaysian Marine Water Quality Criteria and Standard, most of the level of parameters measured remained Class 1, suggesting the physico-chemical environment were in line with sustainable conservation of the marine protected areas and marine parks of this wetland area.
Malaysia depends heavily on rivers as a source for water supply, irrigation, and sustaining the livelihood of local communities. The evolution of land use in urban areas due to rapid development and the continuous problem of illegal discharge have had a serious adverse impact on the health of the country's waterways. Klang River requires extensive rehabilitation and remediation before its water could be utilised for a variety of purposes. A reliable and rigorous remediation work plan is needed to identify the sources and locations of streams that are constantly polluted. This study attempts to investigate the feasibility of utilising a temporal and spatial risk quotient (RQ) based analysis to make an accurate assessment of the current condition of the tributaries in the Klang River catchment area. The study relies on existing data sets on Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), and Ammonia (NH3) to evaluate the water quality at thirty strategic locations. Analysis of ammonia pollution is not only based on the limit established for river health but was expanded to include the feasibility of using the water for water intake, recreational activities, and sustaining fish population. The temporal health of Klang River was evaluated using the Risk Matrix Approach (RMA) based on the frequency of RQ > 1 and associated colour-coded hazard impacts. By using the developed RMA, the hazard level for each parameter at each location was assessed and individually mapped using Geographic Information System (GIS). The developed risk hazard mapping has high potential as one of the essential tools in making decisions for a cost-effective river restoration and rehabilitation.
Epoxidized natural rubber/polyvinyl chloride/microcrystalline cellulose (ENR/PVC/MCC) composite membranes were
prepared and used to treat palm oil mill effluent (POME). The loadings of MCC were varied at 0, 5, 10 and 15 w/w%. The
increment of MCC loads has intensified the hydroxyl peak of the membranes in FTIR spectrum, indicating the increase
in membrane hydrophilicity. MCC acted as a pore forming agent since the ENR/PVC/10% MCC gave the highest water
flux and well-distributed pores. After first treatment of POME, the levels of chemical oxygen demand (COD), biochemical
oxygen demand (BOD) and total suspended solid (TSS) were reduced to 99.9%, 70.3%, and 16.9%, respectively. These
data showed that ENR/PVC/MCC membrane has the potential to treat POME.
This study evaluates the effects of subcritical hydrothermal treatment on palm oil mill effluent (POME) and its concomitant formations of solid hydrochar, liquid product and gaseous product. The reactions were carried out at temperatures ranged 493 K-533 K for 2 h. The highest reduction of chemical oxygen demand (COD) and biochemical oxygen demand (BOD) were 58.8% and 62.5%, respectively, at 533 K. In addition, the removal of total suspended solids (TSS) achieved up to 99%, with the pH of POME reaching 6 from the initial pH 4. The gas chromatography coupled with mass spectroscopy (GC-MS) analysis showed that the fresh POME contained n-Hexadecanoic acid as the dominant component, which gradually reduced in the liquid product in the reaction with increased temperature, in addition to the attenuation of carboxyl compounds and elevation of phenolic components. The gaseous products contained CO2, CO, H2, and C3 - C6 hydrocarbons. Traces of CH4 were only found at 533 K. CO2 is the dominant species, where the highest of 3.99 vol% per 500 mL working volume of POME recorded at 533 K. The solid hydrochars showed negligible morphological changes across the reaction temperature. The O/C atomic ratio of the hydrochar range from 0.157 to 0.379, while the H/C atomic ratio was in the range from 0.930 to 1.506. With the increase of treatment temperature, the higher heating value (HHV) of the hydrochar improved from 24.624 to 27.513 MJ kg-1. The characteristics of hydrochar make it a fuel source with immense potential. POME decomposed into water-soluble compounds, followed by deoxygenation (dehydration and decarboxylation) in producing hydrochar with lower oxygen content and higher aromatic compounds in the liquid product. Little gaseous hydrocarbons were produced due to subcritical hydrothermal gasification at low temperature.