This paper describes the sorption of Pb(ll) from aqueous solution. Oil palm empty fruit bunch (OPEFB) fiber was first grafted with poly(methylacrylate) and then treated with hydroxylammonium chloride in alkaline medium to produce hydroxamic acid (PHA) grafted OPEFB. Sorption of Pb(ll) by PHA-OPEFB was maximum at pH 5. The sorption followed the Langmuir model with maximum capacityof 125.0 mg g-1 at 25 degrees C. The sorption process was exothermic, as shown by the negative value of enthalpy change, Delta H0. The free energy change (DeltaG0) for the sorption was negative, showing that the sorption process was spontaneous. A kinetic study showed that the Pb(ll) sorption followed a second order kinetic model.
Biofouling is a crucial factor in membrane bioreactor (MBR) applications, particularly for high organic loading operations. This paper reports a study on biofouling in an MBR to establish a relationship between critical flux, Jc, mixed liquor suspended solids (MLSS) (ranging from 5 to 20 g L-1) and volumetric loading rate (6.3 kg COD m-3 h-1) of palm oil mill effluent (POME). A lab-scale 100 L hybrid MBR consisting of anaerobic, anoxic, and aerobic reactors was used with flat sheet microfiltration (MF) submerged in the aerobic compartment. The food-to-microorganism (F/M) ratio was maintained at 0.18 kg COD kg-1 MLSSd-1. The biofouling tendency of the membrane was obtained based on the flux against the transmembrane pressure (TMP) behaviour. The critical flux is sensitive to the MLSS. At the MLSS 20 g L-1 the critical flux is about four times lower than that for the MLSS concentration of 5 g L-1. The results showed high removal efficiency of denitrification and nitrification up to 97% at the MLSS concentration 20 g L-1. The results show that the operation has to compromise between a high and a low MLSS concentration. The former will favour a higher removal rate, while the latter will favour a higher critical flux.
The performances of HZSM-5 and transition metal-loaded HZSM-5 (Mn, Cu, Fe, Ti) catalysts during catalytic ozonation of phenol have been investigated. It was observed the performance order for removal of phenol and COD was Mn/HZSM-5 > Fe/HZSM-5 > Cu/HZSM-5 > Ti/HZSM-5 > HZSM-5. The presence of metals on HZSM-5 enhanced the phenol removal capability of HZSM-5. Mn loading on HZSM-5 was optimized due to its high phenol removal capability amongst metal-loaded HZSM-5 catalysts. Experimental results suggested that low amount of Mn loading on HZSM-5 was sufficient for HZSM-5 to act as catalyst and adsorbent. A maximum of 95.8 wt% phenols and 70.2 wt% COD were removed over 2 wt% Mn/HZSM-5 in 120 min. It was supposed that transition metals mainly acted as ozone decomposers due to their multiple oxidation states that enhanced the ozonation of phenol.
Tylosin has been considered inhibiting COD removal in anaerobic digestion. In this study it is proven that this is not always the case. Accordingly, elevated concentrations of Tylosin (100-800mgL-1) could be tolerated by the anaerobic system. The influence of Tylosin concentrations on an up-flow anaerobic stage reactor (UASR) was assessed using additions of Tylosin phosphate concentrate. Results showed high efficiency for COD removal (average 93%) when Tylosin was present at concentrations ranging from 0 to 400 mg L-1. However, at Tylosin concentrations of 600 and 800 mg L-1 treatment efficiency declined to 85% and 75% removal respectively. The impact of Tylosin concentrations on archaeal activity were investigated and the analysis revealed that archaeal cells dominated the reactor, confirming that there was no detectable inhibition of the methanogens at Tylosin levels between 100 and 400mg L-1. Nevertheless, the investigation showed a slight reduction in the number of methanogens at Tylosin levels of 600 and 800 mg L-1. These results demonstrated that the methanogens were well adapted to Tylosin. It would not be expected that the process performance of the UASR would be affected, not even at a level well in excess of those appearing in real wastewater from a Tylosin production site.
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.
The process involved in the local scour below pipelines is so complex that it makes it difficult to establish a general empirical model to provide accurate estimation for scour. This paper describes the use of artificial neural networks (ANN) to estimate the pipeline scour depth. The data sets of laboratory measurements were collected from published works and used to train the network or evolve the program. The developed networks were validated by using the observations that were not involved in training. The performance of ANN was found to be more effective when compared with the results of regression equations in predicting the scour depth around pipelines.
The biodegradation characteristics of palm oil mill effluent (POME) and the related microbial community were studied in both actual sequential anaerobic ponds in Malaysia and enrichment cultures. The significant degradation of the POME was observed in the second pond, in which the temperature was 35-37 °C. In this pond, biodegradation of major long chain fatty acids (LCFA), such as palmitic acid (C16:0) and oleic acid (C18:1), was also confirmed. The enrichment culture experiment was conducted with different feeding substrates, i.e. POME, C16:0 and C18:1, at 35 °C. Good recovery of methane indicated biodegradation of feeds in the POME and C16:0 enrichments. The methane production rate of the C18:1 enrichment was slower than other substrates and inhibition of methanogenesis was frequently observed. Denaturing gradient gel electrophoresis (DGGE) analyses indicated the existence of LCFA-degrading bacteria, such as the genus Syntrophus and Syntorophomonas, in all enrichment cultures operated at 35 °C. Anaerobic degradation of the POME under mesophilic conditions was stably processed as compared with thermophilic conditions.
In this study of coagulation operation, a comparison was made between the optimum jar test values for pH, coagulant and coagulant aid obtained from traditional methods (an adjusted one-factor-at-a-time (OFAT) method) and with central composite design (the standard design of response surface methodology (RSM)). Alum (coagulant) and polymer (coagulant aid) were used to treat a water source with very low pH and high aluminium concentration at Sri-Gading water treatment plant (WTP) Malaysia. The optimum conditions for these factors were chosen when the final turbidity, pH after coagulation and residual aluminium were within 0-5 NTU, 6.5-7.5 and 0-0.20 mg/l respectively. Traditional and RSM jar tests were conducted to find their respective optimum coagulation conditions. It was observed that the optimum dose for alum obtained through the traditional method was 12 mg/l, while the value for polymer was set constant at 0.020 mg/l. Through RSM optimization, the optimum dose for alum was 7 mg/l and for polymer was 0.004 mg/l. Optimum pH for the coagulation operation obtained through traditional methods and RSM was 7.6. The final turbidity, pH after coagulation and residual aluminium recorded were all within acceptable limits. The RSM method was demonstrated to be an appropriate approach for the optimization and was validated by a further test.
A high concentration of phosphorus in wastewater may lead to excessive algae growth and deoxygenation of the water. In this work, nanofiltration (NF) of phosphorus-rich solutions is studied in order to investigate its potential in removing and recycling phosphorus. Wastewater samples from a pulp and paper plant were first analyzed. Commercial membranes (DK5, MPF34, NF90, NF270, NF200) were characterized and tested in permeability and phosphorus removal experiments. NF90 membranes offer the highest rejection of phosphorus; a rejection of more than 70% phosphorus was achieved for a feed containing 2.5 g/L of phosphorus at a pH <2. Additionally, NF90, NF200 and NF270 membranes show higher permeability than DK5 and MPF34 membranes. The separation performance of NF90 is slightly affected by phosphorus concentration and pressure, which may be due to concentration polarization and fouling. By adjusting the pH to 2 or adding sulfuric acid, the separation performance of NF90 was improved in removing phosphorus. However, the presence of acetic acid significantly impairs the rejection of phosphorus.
Conventional aerobic and low-rate anaerobic processes such as pond and open-tank systems have been widely used in wastewater treatment. In order to improve treatment efficacy and to avoid greenhouse gas emissions, conventional treatment can be upgraded to a high performance anaerobic granular-sludge system. The anaerobic granular-sludge systems are designed to capture the biogas produced, rendering a potential for claims of carbon credits under the Kyoto Protocol for reducing emissions of greenhouse gases. Certified Emission Reductions (CERs) would be issued, which can be exchanged between businesses or bought and sold in international markets at the prevailing market prices. As the advanced anaerobic granular systems are capable of handling high organic loadings concomitant with high strength wastewater and short hydraulic retention time, they render more carbon credits than other conventional anaerobic systems. In addition to efficient waste degradation, the carbon credits can be used to generate revenue and to finance the project. This paper presents a scenario on emission avoidance based on a methane recovery and utilization project. An example analysis on emission reduction and an overview of the global emission market are also outlined.
The potential of Pleurotus ostreatus spent mushroom compost (PSMC) as a green biosorbent for nickel (II) biosorption was investigated in this study. A novel approach of using the half-saturation concentration of biosorbent to rapidly determine the uptake, kinetics and mechanism of biosorption was employed together with cost per unit uptake analysis to determine the potential of this biosorbent. Fifty per cent nickel (II) biosorption was obtained at a half-saturation constant of 0.7 g biosorbent concentration, initial pH in the range of 4-8, 10 min contact time, 50 mL 50 mg/L nickel (II) initial concentration. The experimental data were well fitted with the Langmuir isotherm model and the maximum nickel (II) biosorption was 3.04 mg/g. The results corresponded well to a second pseudo order kinetic model with the coefficient of determination value of 0.9999. Based on FTIR analysis, the general alkyl, hydroxyl or amino, aliphatic alcohol and carbonyl functional groups of biosorbent were involved in the biosorption process. Therefore, biosorption of nickel (II) must involve several mechanisms simultaneously such as physical adsorption, chemisorption and ion exchange. Cost comparison for PSMC with Amberlite IRC-86 ion exchange resin indicates that the biosorbent has the potential to be developed into a cost effective and environmentally friendly treatment system.
The Bio-ecological Drainage System, or BIOECODS, is an urban drainage system located at the Engineering Campus, Universiti Sains Malaysia. It consists of a constructed wetland as a part of the urban drainage system to carry storm water in a closed system. In this closed system, the constructed wetland was designed particularly for further treatment of storm water. For the purpose of studying the water balance of the constructed wetland, data collection was carried out for two years (2007 and 2009). The results show that the constructed wetland has a consistent volume of water storage compared to the outflow for both years with correlation coefficients (R(2)) of 0.99 in 2007 and 0.86 in 2009.
The research conducted a study on decomposition and biodegradability enhancement of textile wastewater using a combination of electron beam irradiation and activated sludge process. The purposes of this research are to remove pollutant through decomposition and to enhance the biodegradability of textile wastewater. The wastewater is treated using electron beam irradiation as a pre-treatment before undergo an activated sludge process. As a result, for non-irradiated wastewater, the COD removal was achieved to be between 70% and 79% after activated sludge process. The improvement of COD removal efficiency increased to 94% after irradiation of treated effluent at the dose of 50 kGy. Meanwhile, the BOD(5) removal efficiencies of non-irradiated and irradiated textile wastewater were reported to be between 80 and 87%, and 82 and 99.2%, respectively. The maximum BOD(5) removal efficiency was achieved at day 1 (HRT 5 days) of the process of an irradiated textile wastewater which is 99.2%. The biodegradability ratio of non-irradiated wastewater was reported to be between 0.34 and 0.61, while the value of biodegradability ratio of an irradiated wastewater increased to be between 0.87 and 0.96. The biodegradability enhancement of textile wastewater is increased with increasing the doses. Therefore, an electron beam radiation holds a greatest application of removing pollutants and also on enhancing the biodegradability of textile wastewater.
Central composite design (CCD) and response surface methodology (RSM) were employed to optimize four important variables, i.e. amounts of oil, bacterial inoculum, nitrogen and phosphorus, for the removal of selected n-alkanes during bioremediation of weathered crude oil in coastal sediments using laboratory bioreactors over a 60 day experimentation period. The reactors contained 1 kg soil with different oil, microorganisms and nutrients concentrations. The F Value of 26.89 and the probability value (P < 0.0001) demonstrated significance of the regression model. For crude oil concentration of 2, 16 and 30 g per kg sediments and under optimized conditions, n-alkanes removal was 97.38, 93.14 and 90.21% respectively. Natural attenuation removed 30.07, 25.92 and 23.09% n-alkanes from 2, 16 and 30 g oil/kg sediments respectively. Excessive nutrients addition was found to inhibit bioremediation.
This research investigated the effects of co- and counter-current flow patterns on oil-water-solid separation efficiencies of a circular separator with inclined coalescence mediums. Oil-water-solid separations were tested at different influent concentrations and flowrates. Removal efficiencies increased as influent flowrate decreased, and their correlationship can be represented by power equations. These equations were used to predict the required flowrate, Q(ss50), for a given influent suspended solids concentration C(iss) to achieve the desired effluent suspended solids concentration, C(ess) of 50 mg/L, to meet environmental discharge requirements. The circular separator with counter-current flow was found to attend removal efficiencies relatively higher as compared to the co-current flow. As compared with co-current flow, counter-current flow Q(ss50) was approximately 1.65 times higher than co-current flow. It also recorded 13.16% higher oil removal at influent oil concentration, C(io) of 100 mg/L, and approximately 5.89% higher TSS removal at all influent flowrates. Counter-current flow's better removal performances were due to its higher coalescing area and constant interval between coalescence plate layers.
The removal of Reactive Black 5 dye in an aqueous solution by electrocoagulation (EC) as well as addition of flocculant was investigated. The effect of operational parameters, i.e. current density, treatment time, solution conductivity and polymer dosage, was investigated. Two models, namely the artificial neural network (ANN) and the response surface method (RSM), were used to model the effect of independent variables on percentage of dye removal. The findings of this work showed that current density, treatment time and dosage of polymer had the most significant effect on percentage of dye removal (p<0.001). In addition, interaction between time and current density, time and dosage of polymer, current density and dosage of polymer also significantly affected the percentage of dye removal (p=0.034, 0.003 and 0.024, respectively). It was shown that both the ANN and RSM models were able to predict well the experimental results (R(2)>0.8).
Rock filters are an established technology for polishing waste stabilization pond effluents. However, they rapidly become anoxic and consequently do not remove ammonium-nitrogen. Horizontal-flow aerated rock filters (HFARF), developed to permit nitrification and hence ammonium-N removal, were compared with a novel vertical-flow aerated rock filter (VFARF). There were no differences in the removals of BOD5, TSS and TKN, but the VFARF consistently produced effluents with lower ammonium-N concentrations (<0.3 mg N/L) than the HFARF (0.8-1.5 mg N/L) and higher nitrate-N concentrations (24-29 mg N/L vs. 17-24 mg N/L).
This study deals with the overcapacity problem of water treatment plants in Korea, and mainly discusses status, causes, and engineering options. To this end, we first statistically analyze the recent trend of demand, revealing that the demands of small- and mid-size systems are still increasing while that of large-size systems is now decreasing. Since the existing approach to plan capacity implicitly assumes that demand will increase at a regular rate, we estimate excess capacities and system utilizations of large-size systems. From these results it is found that the large-size systems are suffering from serious overcapacity, thus necessitating that engineers make very difficult decisions given that systems are still expanding the capacities of plants due to a lack of awareness of the current demand trend. For other systems where there is a better understanding of the transition of demand, planners have ceased to expand plants or have closed down relatively old plants in efforts to reduce O&M costs. To address this problem, quick recognition of the transition of demand is being highlighted by the concepts of integrated resources management and cybernetics. Therefore, we examined how quickly the new trend of the Seoul case could be precisely recognized and appropriately addressed. Using the Bayesian parameter estimation method, we found that a new trend can be recognized six years after the transition of demand.
Landfill leachate is one of the major contamination sources. In this study, the ability of synthetic ion exchange resins which carry different mobile ion for removing color, chemical oxygen demand (COD), and ammonia nitrogen (NH(3)-N) from stabilized leachate was investigated. The synthetic resin INDION 225 Na as a cationic exchanger and INDION FFIP MB as an anionic exchanger were used in this study. INDION 225 Na was used in hydrogen form (H(+)) and in sodium form (Na(+)), while INDION FFIP MB resin was used in hydroxide form (OH(-)) and in calcium form (Cl(-)) form. The results indicated better removal of color, COD and NH(3)-N by using INDION 225 Na in H(+) as compared with Na(+) form, while no performance differences were observed by using INDION FFIP MB in OH(-) or Cl(-) form. Applying cationic resin followed by anionic resin achieved 97, 88 and 94, percent removal of color, COD and NH(3)-N. The residual amounts were 160 Pt-Co, 290 mg/L and 110 mg/L of color, COD and NH(3)-N respectively.
Perfluorinated compounds such as perfluorooctane sulfonate (PFOS) and perfluorooctane acid (PFOA) have been recognized as emerging environmental pollutants because of their ubiquitous occurrence in the environment, biota and humans. The paper focuses on the distribution, bioaccumulation and toxic effects of PFOS and PFOA in the water. From the available literature, tap and surface water samples in several countries were found to be contaminated with PFOS and PFOA. These compounds were detected globally in the tissues of fish, bird and marine mammals. Their concentrations from relatively more industrialized areas were greater than those from the less populated and remote locations. Blood samples of occupationally exposed people and the general population in various countries were found to contain PFOS and PFOA which suggested a possibility of atmospheric transport of these compounds. There is still a death of information about the environmental pathways of PFOS and PFOA. The presence of these compounds in the tap water, surface water and animal and human tissues indicates their global contamination and bioaccumulative phenomena in the ecosystems.