A sequencing batch reactor (SBR) with a working volume of 8 L and an exchange ratio of 25% was used to enrich biomass for the treatment of the anaerobically treated low pH palm oil mill effluent (POME). The influent concentration was stepwise increased from 5000 ± 500 mg COD/L to 11,500 ± 500 mg COD/L. The performance of the reactor was monitored at different organic loading rates (OLRs). It was found that approximately 90% of the COD content of the POME wastewater was successfully removed regardless of the OLR applied to the SBR. Cycle studies of the SBR show that the oxygen uptake by the biomass while there is no COD reduction may be due to the oxidation of the storage product by the biomass. Further, the growth kinetic parameters of the biomass were determined in batch experiments using respirometer. The maximum specific growth rate (μmax) was estimated to be 1.143 day(-1) while the half saturation constant (Ks) with respect to COD was determined to be 0.429 g COD/L. The decay coefficient (bD) and biomass yield (Y) were found to be 0.131 day(-1) and 0.272 mg biomass/mg COD consumed, respectively.
In this research, the capability of lateritic soil used as coagulant for the treatment of stabilized leachate from the Penang-Malaysia Landfill Site was investigated. The evaluation of lateritic soil coagulant in comparison with commercialized chemical coagulants, such as alum, was performed using conventional jar test experiments. The optimum pH and coagulant dosage were identified for the lateritic soil coagulant and the comparative alum coagulant. It was found that the application of lateritic soil coagulant was quite efficient in the removal of COD, color and ammoniacal-nitrogen content from the landfill leachate. The optimal pH value was 2.0, while 14 g/L of lateritic soil coagulant was sufficient in removing 65.7% COD, 81.8% color and 41.2% ammoniacal-nitrogen. Conversely, the optimal pH and coagulant dosage for the alum were pH 4.8 and 10 g/L respectively, where 85.4% COD, 96.4% color and 47.6% ammoniacal-nitrogen were removed from the same leachate sample. Additionally, the Sludge Volume Index (SVI) ratio of alum and lateritic soil coagulant was 53:1, which indicated that less sludge was produced and was an environmentally friendly product. Therefore, lateritic soil coagulant can be considered a viable alternative in the treatment of landfill leachate.
A study has been carried out to define the effect of drastic temperature changes on the performance of lab-scale hollow-fibre MBR in treating municipal wastewater at a flux of 10 L m(-2) h(-1) (LMH). The objectives of the study were to estimate the activated sludge properties, the removal efficiencies of COD and NH(3)-N and the membrane fouling tendency under critical conditions of drastic temperature changes (23, 33, 42 & 33 °C) and MLSS concentration ranged between 6,382 and 8,680 mg/L. The study exhibited that the biomass reduction, the low sludge settleability and the supernatant turbidity were results of temperature increase. The temperature increase led to increase in SMP carbohydrate and protein, and to decrease in EPS carbohydrate and protein. The BRE of COD dropped from 80% at 23 °C to 47% at 42 °C, while the FRE was relatively constant at about 90%. Both removal efficiencies of NH(3)-N trended from about 100% at 33 °C to less than 50% at 42 °C. TMP and BWP ascended critically with temperature increase up to 336 and 304 mbar respectively by the end of the experiment. The values of suspended solids (SS) and the turbidity in the final effluent were negligible. The DO in the mixed liquor was varying with temperature change, while the pH was within the range of 6.7-8.3.
This paper examines the storm runoff quality from a commercial area in south Johor, Malaysia. Six storm events with a total of 68 storm runoff samples were analyzed. Event Mean Concentration (EMC) for all constituents analysed showed large inter-event variation. Site mean concentrations (SMC) for total suspended solids (TSS), oil and grease (O&G), biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrate-nitrogen (NO(3)-N), nitrite-nitrogen (NO(2)-N), ammonia-nitrogen (NH(3)-N), total phosphorus (Total P) and Soluble P are 261, 4.31, 74, 192, 1.5, 0.006, 1.9, 1.12 and 0.38 mg/L, respectively. The SMCs at the studied site are higher than those reported in many urban catchments. The mean baseflow concentrations were higher than the EMCs for COD, Soluble P, NH(3)-N, NO(3)-N, Total P and NO(2)-N. However, the reverse was observed for TSS and O&G. All pollutants showed the occurrence of first flush phenomenon with the highest strength was observed for TSS, COD and NH(3)-N.
Titania nanotubes are gaining prominence in photocatalysis, owing to their excellent physical and chemical properties such as high surface area, excellent photocatalytic activity, and widespread availability. They are easily produced by a simple and effective hydrothermal method under mild temperature and pressure conditions. This paper reviews and analyzes the mechanism of titania nanotube formation by hydrothermal treatment. It further examines the parameters that affect the formation of titania nanotubes, such as starting material, sonication pretreatment, hydrothermal temperature, washing process, and calcination process. Finally, the effects of the presence of dopants on the formation of titania nanotubes are analyzed.
This article presents a review on the role of oil palm biomass (trunks, fronds, leaves, empty fruit bunches, shells, etc.) as adsorbents in the removal of water pollutants such as acid and basic dyes, heavy metals, phenolic compounds, various gaseous pollutants, and so on. Numerous studies on adsorption properties of various low-cost adsorbents, such as agricultural wastes and its based activated carbons, have been reported in recent years. Studies have shown that oil palm-based adsorbent, among the low-cost adsorbents mentioned, is the most promising adsorbent for removing water pollutants. Further, these bioadsorbents can be chemically modified for better efficiency and can undergo multiple reuses to enhance their applicability at an industrial scale. It is evident from a literature survey of more than 100 recent papers that low-cost adsorbents have demonstrated outstanding removal capabilities for various pollutants. The conclusion is been drawn from the reviewed literature, and suggestions for future research are proposed.
In this review article, the use of various low-cost adsorbents for the removal of pesticides from water and wastewater has been reviewed. Pesticides may appear as pollutants in water sources, having undesirable impacts to human health because of their toxicity, carcinogenicity, and mutagenicity or causing aesthetic problems such as taste and odors. These pesticides pollute the water stream and it can be removed very effectively using different low-cost adsorbents. It is evident from a literature survey of about 191 recently published papers that low-cost adsorbents have demonstrated outstanding removal capabilities for pesticides.
Water scarcity and pollution rank equal to climate change as the most urgent environmental issue for the 21st century. To date, the percolation landfill leachate into the groundwater tables and aquifer systems which poses a potential risk and potential hazards towards the public health and ecosystems, remains an aesthetic concern and consideration abroad the nations. Arising from the steep enrichment of globalization and metropolitan growth, numerous mitigating approaches and imperative technologies have currently drastically been addressed and confronted. Confirming the assertion, this paper presents a state of art review of leachate treatment technologies, its fundamental background studies, and environmental implications. Moreover, the key advance of activated carbons adsorption, its major challenges together with the future expectation are summarized and discussed. Conclusively, the expanding of activated carbons adsorption represents a potentially viable and powerful tool, leading to the superior improvement of environmental conservation.
During the last century, a great deal of research and development as well as applications has been devoted to waste. These include waste minimization and treatment, the environmental assessment of waste, minimization of environmental impact, life cycle assessment and others. The major reason for such huge efforts is that waste generation constitutes one of the major environmental problems where production industries are concerned. Until now, an increasing pressure has been put on finding methods of reusing waste, for instance through cleaner production, thus mirroring rapid changes in environmental policies. The palm oil industry is one of the leading industries in Malaysia with a yearly production of more than 13 million tons of crude palm oil and plantations covering 11% of the Malaysian land area. However, the production of such amounts of crude palm oil result in even larger amounts of palm oil mill effluent (POME), estimated at nearly three times the quantity of crude palm oil. Normally, POME is treated using end-of-pipe processes, but it is worth considering the potential value of POME prior to its treatment through introduction of a cleaner production. It is envisaged that POME can be sustainably reused as a fermentation substrate in the production of various metabolites, fertilizers and animal feeds through biotechnological advances. The present paper thus discusses various technically feasible and economically beneficial means of transforming the POME into low or preferably high value added products.
In this paper, the ability of coconut bunch waste (CBW), an agricultural waste available in large quantity in Malaysia, to remove basic dye (methylene blue) from aqueous solution by adsorption was studied. Batch mode experiments were conducted at 30 degrees C to study the effects of pH and initial concentration of methylene blue (MB). Equilibrium adsorption isotherms and kinetics were investigated. The experimental data were analyzed by the Langmuir, Freundlich and Temkin models of adsorption. The adsorption isotherm data were fitted well to Langmuir isotherm and the monolayer adsorption capacity was found to be 70.92 mg/g at 30 degrees C. The kinetic data obtained at different concentrations have been analyzed using a pseudo-first-order, pseudo-second-order equation and intraparticle diffusion equation. The experimental data fitted very well the pseudo-second-order kinetic model.
A new method of Standard Malaysian Rubber (SMR) process wastewater treatment was developed based on in situ hypochlorous acid generation. The hypochlorous acid was generated in an undivided electrolytic cell consisting of two sets of graphite as anode and stainless sheets as cathode. The generated hypochlorous acid served as an oxidizing agent to destroy the organic matter present in the SMR wastewater. For an influent COD concentration of 2960 mg/L at an initial pH 4.5+/-0.1, current density 74.5 mA/cm(2), sodium chloride content 3% and electrolysis period of 75 min, resulted in the following residual values pH 7.5, COD 87 mg/L, BOD(5) 60 mg/L, TOC 65 mg/L, total chlorine 146 mg/L, turbidity 7 NTU and temperature 48 degrees C, respectively. In the case of 2% sodium chloride as an electrolyte for the above said operating condition resulted in the following values namely: pH 7.2, COD 165 mg/L, BOD(5) 105 mg/L, TOC 120 mg/L, total chlorine 120 mg/L, turbidity 27 NTU and temperature 53 degrees C, respectively. The energy requirement were found to be 30 and 46 Wh/L, while treating 24 L of SMR wastewater at 2 and 3% sodium chloride concentration at a current density 74.5 mA/cm(2). The observed energy difference was due to the improved conductivity at high sodium chloride content.
A study was conducted to investigate the efficiency of coagulation and flocculation processes for removing colour from a semi-aerobic landfill leachate from one of the landfill sites in Malaysia. Four types of coagulant namely aluminium (III) sulphate (alum), ferric (III) chloride, ferrous (II) sulphate and ferric (III) sulphate were studied using standard jar test apparatus. Results indicated that ferric chloride was superior to the other coagulants and removed 94% of colour at an optimum dose of 800 mg/l at pH 4. The effect of coagulant dosages on colour removal showed similar trend as for COD, turbidity and suspended solids. This suggested that colour in landfill leachate was mainly contributed by organic matters with some insoluble forms that exhibited turbidity and suspended solids readings. The results from this study suggested that ferric chloride could be a viable coagulant in managing colour problems associated with landfill leachate.
A study on liquid state bioconversion of sewage treatment plant (STP) sludge was assisted to evaluate the performance of batch fermenter compared to shake flask in a laboratory. Bioconversion of STP sludge was highly influenced by the mixed fungal culture of Penicillium corylophilum and Aspergillus niger after 4 days of treatment. The results showed that about 24.9 g kg(-1) dry sludge cake (DSC) was produced with enrichment of fungal biomass protein in fermenter while 20.1 g kg(-1) in shake flask after 4 days of fungal treatment. The effective biodegradation of STP sludge was recorded in both fermenter and shake flask experiment compared to control (uninnoculated sample). The results presented in this study revealed that the overall performance of fermenter in terms of sludge cake (biosolids) accumulation and biodegradation of STP sludge was higher than the shake flask.
Studies on the removal of phenol from aqueous solutions by adsorption on sewage treatment plant biosolids (BS) as low-cost adsorbent were carried out with an aim to obtain information on treating phenol-containing wastewater from different industries. A series of experiments were undertaken in a batch adsorption technique to access the effect of the process variables i.e. initial phenol concentration, contact time, initial pH and adsorbent dose. The results showed that the adsorption capacity of BS in aqueous solution increased with the decrease in initial concentration and pH, and increase in contact time and dose of adsorbent. The experimental results were fitted by Langmuir and Freundlich isotherms to describe the biosorption processes.
Tubular nanofiltration membrane performance to treat water for reuse was carried out by choosing C.I. Acid Black 210 dye as a model dye. It has been shown that increasing pH causes reduction in irreversible fouling factor (IFF) and the dye removal is also affected by solution pH. The total organic carbon removal for pH 4, pH 7, pH 8 and pH 10 is 97.9, 92.3, 94.5 and 94.6%, respectively. The conductivity removal for pH 4, pH 7, pH 8 and pH 10 is 85.1, 88.3, 87.8 and 90.7% respectively. The increase in the initial dye concentration causes rapid increase in fouling until 100 mg/l. Then the fouling increases gradually as it reaches a maximum IFF around 13%. This study also shows that the colour of permeate changes from colourless to light greenish/yellowish (initial concentration of 2,000 and 4,000 mg/l) as the initial dye concentration increases. The conductivity removal was also reduced as the initial dye concentration increased due to screening of the Donnan effect with the presence of salt.
The performance of a commercially available palm shell based activated carbon to remove lead ions from aqueous solutions by adsorption was evaluated. The adsorption experiments were carried out at pH 3.0 and 5.0. The effect of malonic and boric acid presence on the adsorption of lead ions was also studied. Palm shell activated carbon showed high adsorption capacity for lead ions, especially at pH 5 with an ultimate uptake of 95.2mg/g. This high uptake showed palm shell activated carbon as amongst the best adsorbents for lead ions. Boric acid presence did not affect significantly lead uptake, whereas malonic acid decreased it. The diffuse layer surface complexation model was applied to predict the extent of adsorption. The model prediction was found to be in concordance with the experimental values.
Large volumes of untreated palm oil mill effluent (POME) pose threat to aquatic environment due to the presence of very high organic content. The present investigation involved two pilot-scale anaerobic expanded granular sludge bed (EGSB) reactors, continuously operated for 1 year to treat POME. Setting HRT at 9.8 d, the anaerobic EGSB reactors reduced COD from 71179 mg/L to 12341 mg/L and recycled half of sludge by a dissolved air flotation (DAF). The average effluent COD was 3587 mg/L with the consistent COD removal efficiency of 94.89%. Adding cationic polymer (PAM) dose of 30 mg/L to DAF unit and recycling its half of sludge caused granulation of anaerobic sludge. Bacilli and small coccid bacteria were the dominant microbial species of the reactor. The reactor produced 27.65 m(3) of biogas per m(3) of POME which was utilized for electricity generation.
Palm oil mill effluent (POME) is a by-product of the palm industry and it releases large amounts of greenhouse gases (GHGs). Water systems are also contaminated by POME if it is released into nonstandard ponds or rivers where it endangers the lives of fish and water fowl. In this paper, the environmental bottlenecks faced by palm oil production were investigated by analyzing the data collected from wet extraction palm oil mills (POMs) located in Malaysia. Strategies for reducing pollution and technologies for GHG reduction from the wet extraction POMs were also proposed. Average GHG emissions produced from processing 1 ton of crude palm oil (CPO) was 1100 kg CO2eq. This amount can be reduced to 200 kg CO2eq by capturing biogases. The amount of GHG emissions from open ponds could be decreased from 225 to 25 kg CO2eq/MT CPO by covering the ponds. Installation of biogas capturing system can decrease the average of chemical oxygen demand (COD) to about 17,100 mg/L and stabilizing ponds in the final step could decrease COD to 5220 mg/L. Using a biogas capturing system allows for the reduction of COD by 80% and simultaneously using a biogas capturing system and by stabilizing ponds can mitigate COD by 96%. Other ways to reduce the pollution caused by POME, including the installation of wet scrubber vessels and increasing the performance of biogas recovery and biogas upgrading systems, are studied in this paper.
Ten filamentous fungi adapted to domestic wastewater sludge (DWS) were further studied to evaluate their potential in terms of adaptation to higher sludge supplemented growing media and phytopathogenicity (induction of diseases to plants) to three germinating crop (Corn: Zea mays, Mung bean: Phaseolus aureus and Mustard: Brassica napus) seeds. The performances of the fungi in seed germination were evaluated based on percent germination index (GI) and infected/spotted seeds on direct fungal biomass (FBM) and fungal metabolite (FM). Significantly the highest biomass production was achieved with RW-P1 512 and Penicillium corylophilum (WW-P1003) at the highest (25%) sludge supplemented growing media that implied its excellent potentiality of adaptation and multiplication to domestic wastewater sludge. Significantly encouraging results of percent GI and spotted/infected seedlings were observed in FM than FBM by all fungi except the strain Aspergillus niger. A. niger gave the poorest percent of GI (24.30, 26.98 and 00.00%) and the highest percent of infected/spotted seeds (70, 100, and 100%) using FBM for corn, mung bean and mustard, respectively. On the other hand, comparatively the highest percent of GI (107.99, 106.25 and 117.67%) and the lowest percent of spotted/infected seedlings (3.3, 3.3 and 3.3%) were achieved with the isolate RW-P1 512 using FM. In FBM, the superior results of percent GI (86.61, 95.92 and 83.87%) and spotted/infected seedlings (3.3, 63.3 and 43.3%) were obtained by A. versicolor. Several crop seeds were responded differently for different fungal treatments. Hundred percent infected/spotted seeds in FM were recorded only for mustard with Trichoderma family that implied its strong sensitiveness to its metabolites.
Several types of water treatment technologies including adsorption are now being used to treat polluted water. In this paper the removal of phenol by adsorption will be discussed. Activated carbons are successfully applied for purification of potable water and the removal of organic pollutants in wastwater. This paper is concerned with a low cost approach to treating waste water that is significant especially for those countries where oil palm is an available agricultural product like Malaysia, Ivory Coast, Nigeria, Thailand, Papua New Guinea. In the coastal region coconut is an available agricultural product and activated carbon prepared using coconut shell is also an economical method of water treatment. The materials used in this study were Commercial Activated Carbon (CAC), prepared from coconut shell and Modified Oil Palm Shell (MOPAS) of 1 to 2 mm diameters. The surface area of CAC and MOPAS was 38.5 m2/g and 38.2 m2/g respectively and the iodine number was determined as 674 and 454 for CAC and MOPAS, respectively. From the study the result shows above 70% removal efficiency for 5 mg/L and 40% removal efficiency for 20 mg/L of phenol solution. The performance efficiency will be discussed based on batch test, following Freundlich adsorption isotherm. The results indicate that CAC exhibits a higher adsorptive capacity (Kf of 0.079) as compared to MOPAS (Kf of 0.048). Hence a better removal efficiency for CAC at lower concentration of phenol. Results from column tests show a better adsorptive capacity for CAC (2.73) as compared to MOPAS (2.48).