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
Sampling of urban runoff was carried out in a small catchment, which represents a residential area (3.34 ha) in Skudai, Johor. One hundred and seventeen runoff samples from ten storm events were analysed. Runoff quality showed large variations in concentrations during storms, especially for SS, BOD5 and COD. Concentrations of NO3-N, NO2-N, NH3-N, and P were also high. Lead (Pb) was also detected but the levels were low (<0.001 mg/L). In general, the river quality is badly polluted and falls in Class V based on the Malaysian Interim National Water Quality Standards. Event mean concentrations for all parameters were found to vary greatly between storms. The values (mg/L) were BOD5 (72), COD (325), SS (386), NO3-N (2.5), NO2-N (0.58), NH3-N (6.8), P (3.4), respectively. First flush phenomena were observed for BOD, COD, SS, NO3-N, NH3-N and P. The first 20-30% of the runoff volume evacuated between 20-59% BOD, 15-69% COD, 15-78% SS, 14-49% NO3-N, 14-19% NO2-N, 23-53% NH3-N and 23-43% P.
Matched MeSH terms: Water Pollutants, Chemical/analysis*
Landfills are one of the main point sources of groundwater pollution. This research mainly aims to assess the risk of nitrate [Formula: see text] transport from the unlined landfill to subsurface layers and groundwater using experimental results and the SESOIL model. Samples from 12 groundwater wells downstream of the landfill were collected and analyzed in 2008, 21 years after the landfill construction. The average [Formula: see text] concentration in the wells was 54 mg/L, slightly higher than the World Health Organization ([Formula: see text] 50 mg/L) standards. SESOIL model was used to predict the [Formula: see text] concentration at the bottom of the unsaturated zone. Results indicated that the current mean [Formula: see text] concentration at the bottom of the unsaturated zone is 75 mg/L. the model predicted that the level of NO3 will increased up to 325 mg/L within 30 years. Accordingly, the [Formula: see text] concentration in groundwater wells near the landfill area is expected to gradually increase with time. Although the current risk associated with the [Formula: see text] level might not be harm to adults, however, it might pose severe risks to both adults and infants in the near future due to [Formula: see text] leaching. Urgent mitigation measures such as final cell cover (cap), lining system and vertical expansion should be considered at the landfill to protect the public health in the area.
This paper reviews the related literature reported in 2019 about various types of wastewaters associated with chemical and allied products. The subjects comprise wastewaters produced from various activities in agricultural, chemical, dye, petrochemical, and pharmaceutical. PRACTITIONER POINTS: Bioflocculant chitosan was used for sludge dewatering and the treatment of water and wastewater, and polishing of sanitary landfill leachate. Alkaline lignin-based flocculants were used to achieve excellent color removal for paper mill sludge. Powdered activated coke was used to remove COD (chemical oxygen demand) from chemical industry wastewater effluents.
Zeolites P in sodium (NaP) and potassium (KP) forms were used as adsorbents for the removal of calcium (Ca2+) and zinc (Zn2+) cations from aqueous solutions. Zeolite KP was prepared by ion exchange of K+ with Na+ which neutralizes the negative charge of the zeolite P framework structure. The ion exchange capacity of K+ on zeolite NaP was determined through the Freundlich isotherm equilibrium study. Characterization of zeolite KP was determined using infrared spectroscopy and X-ray diffraction (XRD) techniques. From the characterization, the structure of zeolite KP was found to remain stable after the ion exchange process. Zeolites KP and NaP were used for the removal of Ca and Zn from solution. The amount of Ca2+ and Zn2+ in aqueous solution before and after the adsorption by zeolites was analysed using the flame atomic absorption spectroscopy method. The removal of Ca2+ and Zn2+ followed the Freundlich isotherm rather than the Langmuir isotherm model. This result also revealed that zeolite KP adsorbs Ca2+ and Zn2+ more than zeolite NaP and proved that modification of zeolite NaP with potassium leads to an increase in the adsorption efficiency of the zeolite. Therefore, the zeolites NaP and KP can be used for water softening (Ca removal) and reducing water pollution/toxicity (Zn removal).
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification; Water Pollutants, Chemical/chemistry
The objective of this study was to investigate the performance of employing persulfate reagent in the advanced oxidation of ozone to treat stabilized landfill leachate in an ozone reactor. A central composite design (CCD) with response surface methodology (RSM) was applied to evaluate the relationships between operating variables, such as ozone and persulfate dosages, pH, and reaction time, to identify the optimum operating conditions. Quadratic models for the following four responses proved to be significant with very low probabilities (<0.0001): COD, color, NH3-N, and ozone consumption (OC). The obtained optimum conditions included a reaction time of 210 min, 30 g/m(3) ozone, 1g/1g COD0/S2O8(2-) ratio, and pH 10. The experimental results were corresponded well with predicted models (COD, color, and NH3-N removal rates of 72%, 96%, and 76%, respectively, and 0.60 (kg O3/kg COD OC). The results obtained in the stabilized leachate treatment were compared with those from other treatment processes, such as ozone only and persulfate S2O8(2-) only, to evaluate its effectiveness. The combined method (i.e., O3/S2O8(2-)) achieved higher removal efficiencies for COD, color, and NH3-N compared with other studied applications. Furthermore, the new method is more efficient than ozone/Fenton in advanced oxidation process in the treatment of the same studied leachate.
Matched MeSH terms: Water Pollutants, Chemical/chemistry*
Landfill leachate is a heavily polluted and a likely hazardous liquid that is produced as a result of water infiltration through solid wastes generated industrially and domestically. This study investigates the potential of using psyllium husk as coagulant and coagulant aid for the treatment of landfill leachate. Psyllium husk has been tested as primary coagulant and as coagulant aid with poly-aluminum chloride (PACl) and aluminum sulfate (alum). As primary coagulant, the optimum dosage and pH for PACl were 7.2 and 7.5 g/L, respectively, with removal efficiencies of 55, 80 and 95% for COD, color and TSS, respectively. For alum, the optimum conditions were 11 g/L alum dosage and pH 6.5 with removal efficiencies of 58, 79 and 78% for COD, color and TSS, respectively. The maximum removal efficiencies of COD, color and TSS were 64, 90 and 96%, respectively, when psyllium husk was used as coagulant aid with PACl. Based on the results, psyllium husk was found to be more effective as coagulant aid with PACl in the removal of COD, color and TSS as compared to alum. Zeta potential test was carried out for leachate, PACl, alum and psyllium husk before and after running the jar test to enhance the results of the jar test experiments.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
Mature landfill leachate is typically non-biodegradable and contains high concentration of refractory organics. The aim of this research was to optimize operating parameters in electro-Fenton process, for the removal of recalcitrant organics from semi-aerobic landfill leachate using response surface methodology (RSM). Effectiveness of important process parameters H(2)O(2)/Fe(2+) molar ratio, current density, pH and reaction time were determined, optimized and modeled successfully. Significant quadratic polynomial models were obtained (R(2)=0.9972 and 0.9984 for COD and color removals, respectively). Numerical optimization based on desirability function were employed; in a 43 min trial 94.07% of COD and 95.83% of color were removed at pH 3 and H(2)O(2)/Fe(2+) molar ratio 1, while current density was 49 mA/cm(2). The results indicate that E-Fenton process was an effective technology for semi-aerobic landfill leachate treatment.
Matched MeSH terms: Water Pollutants, Chemical/analysis; Water Pollutants, Chemical/chemistry*
The performance of a carbon-mineral composite adsorbent used in a fixed bed column for the removal of ammoniacal nitrogen and aggregate organic pollutant (COD), which are commonly found in landfill leachate, was evaluated. The breakthrough capacities for ammoniacal nitrogen and COD adsorption were 4.46 and 3.23 mg/g, respectively. Additionally, the optimum empty bed contact time (EBCT) was 75 min. The column efficiency for ammoniacal nitrogen and COD adsorption using fresh adsorbent was 86.4% and 92.6%, respectively, and these values increased to 90.0% and 93.7%, respectively, after the regeneration process.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification; Water Pollutants, Chemical/chemistry
In the present study, Electrochemical Oxidation was used to remove COD and color from semi-aerobic landfill leachate collected from Pulau Burung Landfill Site (PBLS), Penang, Malaysia. Experiments were conducted in a batch laboratory-scale system in the presence of NaCl as electrolyte and aluminum electrodes. Central composite design (CCD) under Response surface methodology (RSM) was applied to optimize the electrochemical oxidation process conditions using chemical oxygen demand (COD) and color removals as responses, and the electrolyte concentrations, current density and reaction time as control factors. Analysis of variance (ANOVA) showed good coefficient of determination (R(2)) values of >0.98, thus ensuring satisfactory fitting of the second-order regression model with the experimental data. In un-optimized condition, maximum removals for COD (48.77%) and color (58.21%) were achieved at current density 80 mA/cm(2), electrolyte concentration 3,000 mg/L and reaction time 240 min. While after optimization at current density 75 mA/cm(2), electrolyte concentration 2,000 mg/L and reaction time 218 min a maximum of 49.33 and 59.24% removals were observed for COD and color respectively.
Matched MeSH terms: Water Pollutants, Chemical/analysis
Suspended solids, colour and chemical oxygen demand (COD) are among the main pollutants in landfill leachate. Application of physical or biological processes alone is normally not sufficient to remove these constituents, especially for leachate with a lower biochemical oxygen demand (BOD)/ COD ratio. The main objective of this research was to investigate the efficiency of coagulation and flocculation processes for removing suspended solids, colour and COD from leachate produced in a semi-aerobic landfill in Penang, Malaysia. A 12-month characterization study of the leachate indicated that it had a mean annual BOD/COD ratio of 0.15 and was partially stabilized, with little further biological degradation likely to occur. Particle size analysis of the raw leachate indicated that its 50th percentile (d50) was 11.68 microm. Three types of coagulants were examined in bench scale jar test studies: aluminium sulphate (alum), ferric chloride (FeCl3) and ferrous sulphate (FeSO4). The effects of agitation speed, settling time, pH, coagulant dosages and temperature were examined. At 300 rpm of rapid mixing, 50 rpm of slow mixing, and 60 min settling time, higher removals of suspended solids (over 95%), colour (90%) and COD (43%) were achieved at pH 4 and 12. FeCl3 was found to be superior to other coagulants tested. At pH 4 and 12, fair removal of suspended solids was observed at a reasonably low coagulant dose, i.e., 600 mg L(-1); hHowever, about 2500 mg L(-1) of coagulant was required to achieve good removals at pH 6. Better removals were achieved at higher temperature. The d50 of sludge after coagulation at pH 4 with a 2500 mg L(-1) FeCl3 dose was 60.16 microm, which indicated that the particles had been removed effectively from the leachate. The results indicate that coagulation and flocculation processes can be used effectively in integrated semi-aerobic leachate treatment systems, especially for removing suspended solids, colour and COD.
Matched MeSH terms: Water Pollutants, Chemical/analysis*
Horizontal subsurface-flow (HSF) constructed wetland incorporating baffles was developed to facilitate upflow and downflow conditions so that the treatment of pollutants could be achieved under multiple aerobic, anoxic and anaerobic conditions sequentially in the same wetland bed. The performances of the baffled and conventional HSF constructed wetlands, planted and unplanted, in the removal of azo dye Acid Orange 7 (AO7) were compared at the hydraulic retention times (HRT) of 5, 3 and 2 days when treating domestic wastewater spiked with AO7 concentration of 300 mg/L. The planted baffled unit was found to achieve 100%, 83% and 69% AO7 removal against 73%, 46% and 30% for the conventional unit at HRT of 5, 3 and 2 days, respectively. Longer flow path provided by baffled wetland units allowed more contact of the wastewater with the rhizomes, microbes and micro-aerobic zones resulting in relatively higher oxidation reduction potential (ORP) and enhanced performance as kinetic studies revealed faster AO7 biodegradation rate under aerobic condition. In addition, complete mineralization of AO7 was achieved in planted baffled wetland unit due to the availability of a combination of aerobic, anoxic and anaerobic conditions.
Matched MeSH terms: Water Pollutants, Chemical/analysis; Water Pollutants, Chemical/isolation & purification*
The Malaysian palm oil industry is a major revenue earner and the country is ranked as one of the largest producers in the world. However, growth of the industry is synonymous with a massive production of agro-industrial wastewater. As an environmental protection and public health concern, the highly polluting palm oil mill effluent (POME) has become a major attention-grabber. Hence, the industry is targeting for POME pollution abatement in order to promote a greener image of palm oil and to achieve sustainability. At present, most palm oil mills have adopted the ponding system for treatment. Due to the successful POME pollution abatement experiences, Malaysia is currently planning to revise the effluent quality standards towards a more stringent discharge limits. Hence, the current trend of POME research focuses on developing tertiary treatment or polishing systems for better effluent management. Biotechnologically-advanced POME tertiary (polishing) technologies as well as other physicochemical methods are gaining much attention as these processes are the key players to push the industry towards the goal of environmental sustainability. There are still ongoing treatment technologies being researched and the outcomes maybe available in a while. However, the research completed so far are compiled herein and reported for the first time to acquire a better perspective and insight on the subject with a view of meeting the new standards. To this end, the most feasible technology could be the combination of advanced biological processes (bioreactor systems) with extended aeration, followed by solids separation prior to discharge. Chemical dosing is favoured only if effluent of higher quality is anticipated.
Matched MeSH terms: Water Pollutants, Chemical/metabolism*
In recent times, surface water resource in the Western Region of Ghana has been found to be inadequate in supply and polluted by various anthropogenic activities. As a result of these problems, the demand for groundwater by the human populations in the peri-urban communities for domestic, municipal and irrigation purposes has increased without prior knowledge of its water quality. Water samples were collected from 14 public hand-dug wells during the rainy season in 2013 and investigated for total coliforms, Escherichia coli, mercury (Hg), arsenic (As), cadmium (Cd) and physicochemical parameters. Multivariate statistical analysis of the dataset and a linear stoichiometric plot of major ions were applied to group the water samples and to identify the main factors and sources of contamination. Hierarchal cluster analysis revealed four clusters from the hydrochemical variables (R-mode) and three clusters in the case of water samples (Q-mode) after z score standardization. Principal component analysis after a varimax rotation of the dataset indicated that the four factors extracted explained 93.3 % of the total variance, which highlighted salinity, toxic elements and hardness pollution as the dominant factors affecting groundwater quality. Cation exchange, mineral dissolution and silicate weathering influenced groundwater quality. The ranking order of major ions was Na(+) > Ca(2+) > K(+) > Mg(2+) and Cl(-) > SO4 (2-) > HCO3 (-). Based on piper plot and the hydrogeology of the study area, sodium chloride (86 %), sodium hydrogen carbonate and sodium carbonate (14 %) water types were identified. Although E. coli were absent in the water samples, 36 % of the wells contained total coliforms (Enterobacter species) which exceeded the WHO guidelines limit of zero colony-forming unit (CFU)/100 mL of drinking water. With the exception of Hg, the concentration of As and Cd in 79 and 43 % of the water samples exceeded the WHO guideline limits of 10 and 3 μg/L for drinking water, respectively. Reported values in some areas in Nigeria, Malaysia and USA indicated that the maximum concentration of Cd was low and As was high in this study. Health risk assessment of Cd, As and Hg based on average daily dose, hazard quotient and cancer risk was determined. In conclusion, multiple natural processes and anthropogenic activities from non-point sources contributed significantly to groundwater salinization, hardness, toxic element and microbiological contamination of the study area. The outcome of this study can be used as a baseline data to prioritize areas for future sustainable development of public wells.
Matched MeSH terms: Water Pollutants, Chemical/analysis*
In this study, chitosan/polyvinyl alcohol/TiO2 nanofiber was fabricated via electrospinning at a pump rate of 1.5 mL/h and voltage 6 kV. Field-emission scanning electron microscopic images showed bead free finer nanofiber. Fourier transform infrared spectra proved the formation of strong bond among chitosan, polyvinyl alcohol and TiO2. X-ray powder diffraction showed that TiO2 became amorphous in the composite nanofiber. Toughness and thermal stability of the chitosan/PVA nanofibrous membrane was increased with addition TiO2. The chitosan/PVA/TiO2 nanofibrous membrane was stable at basic medium. But degraded in acidic and water medium after 93 and 162 h, respectively. The adsorption mechanism of congo red obeyed the Langmuir isotherm model. On the other hand, adsorption characteristic of methyl orange fitted well with both Langmuir and Freundlich isotherm models. The maximum adsorption capacity of the resulting membrane for congo red and methyl orange is 131 and 314 mg/g, respectively. However, a high dose of adsorbent was required for congo red.
Matched MeSH terms: Water Pollutants, Chemical/chemistry
Landfills are a source of groundwater pollution in Gaza Strip. This study focused on Deir Al Balah landfill, which is a unique sanitary landfill site in Gaza Strip (i.e., it has a lining system and a leachate recirculation system). The objective of this article is to assess the generated leachate quantity and percolation to the groundwater aquifer at a specific site, using the approaches of (i) the hydrologic evaluation of landfill performance model (HELP) and (ii) the water balance method (WBM). The results show that when using the HELP model, the average volume of leachate discharged from Deir Al Balah landfill during the period 1997 to 2007 was around, 6800 m3/year. Meanwhile, the average volume of leachate percolated through the clay layer was 550 m3/year, which represents around 8% of the generated leachate. Meanwhile, the WBM indicated that the average volume of leachate discharged from Deir Al Balah landfill during the same period was around 7660 m3/year--about half of which comes from the moisture content of the waste, while the remainder comes from the infiltration of precipitation and re-circulated leachate. Therefore, the estimated quantity of leachate to groundwater by these two methods was very close. However, compared with the measured leachate quantity, these results were overestimated and indicated a dangerous threat to the groundwater aquifer, as there was no separation between municipal, hazardous and industrial wastes, in the area.
Matched MeSH terms: Water Pollutants, Chemical/analysis; Water Pollutants, Chemical/chemistry*
Pollutants put great stress on the environment, especially the aquatic ecosystem; therefore, the ease with which pollutants migrate in water is a subject of global concern. In this study, leachate from landfill that was analyzed with the objective of understanding the potential impact to the environment was tested on Pangasius sutchi. Heavy metals available at various concentrations in raw leachate samples of both closed and active landfills necessitated the determination of their degree of bioaccumulation in this fish species in order to enrich the risk data on toxicity of effluents. Zinc (3.2 µg g(-1)), iron (2.1 µg g(-1)) and chromium (0.24 µg g(-1)) detected in the fish within 96 h of acute exposure is of concern. A histopathology test on excised liver of P. sutchi indicated cellular disruption from normal stain. Heterogeneous effluents like leachate may affect not only groundwater but can endanger aquatic ecosystems, especially in some regions where improper waste disposal and treatment allow the flow of leachate into surface water courses. Though metals might be beneficial to organisms, the extent at which they can accumulate in leachate-exposed fish is a risk and can initiate metal toxicity in aquatic life.
Matched MeSH terms: Water Pollutants, Chemical/toxicity*
Landfilling is a major option in waste management hierarchy in developing nations. It generates leachate, which has the potential of polluting watercourses. This study analysed the physico-chemical components of leachate from a closed sanitary landfill in Malaysia, in relation to evaluating the toxicological impact on fish species namely Pangasius sutchi S., 1878 and Clarias batrachus L., 1758. The leachate samples were taken from Air Hitam Sanitary Landfill (AHSL) and the static method of acute toxicity testing was experimented on both fish species at different leachate concentrations. Each fish had an average of 1.3 ± 0.2 g wet weight and length of 5.0 ± 0.1 cm. Histology of the fishes was examined by analysing the gills of the response (dead) group, using the Harris haemtoxylin and eosin (H&E) method. Finneys' Probit method was utilized as a statistical tool to evaluate the data from the fish test. The physico-chemical analysis of the leachate recorded pH 8.2 ± 0.3, biochemical oxygen demand 3500 ± 125 mg L(-1), COD 10 234 ± 175 mg L(-1), ammonical nitrogen of 880 ± 74 mg L(-1), benzene 0.22 ± 0.1 mg L(-1) and toluene 1.2 ± 0.4 mg L(-1). The 50% lethality concentration (LC(50)) values calculated after 96 h exposure were 3.2% (v/v) and 5.9% (v/v) of raw leachate on P. sutchi and C. batrachus, respectively. The H&E staining showed denaturation of the nucleus and cytoplasm of the gills of the response groups. Leachate from the sanitary landfill was toxic to both fish species. The P. sutchi and C. batrachus may be used as indicator organisms for leachate pollution in water.
Matched MeSH terms: Water Pollutants, Chemical/analysis; Water Pollutants, Chemical/toxicity*; Water Pollutants, Chemical/chemistry
Terrestrial plants as potential phytoremediators for remediation of surface soil contaminated with toxic metals have gained attention in clean-up technologies. The potential of kenaf (Hibiscus cannabinus L.) to offer a cost-effective mechanism to remediate Fe and As from landfill leachate-contaminated soil was investigated. Pot experiment employing soil polluted with treatments of Jeram landfill leachate was conducted for 120 days. Plants were harvested after 8th, 12th, and 16th weeks of growth. Accumulation of Fe and As was assessed based on Bioconcentration Factor and Translocation Factor. Results showed sequestration of 0.06-0.58 mg As and 66.82-461.71 mg Fe per g plant dry weight in kenaf root, which implies that kenaf root can be an bioavailable sink for toxic metals. Insignificant amount of Fe and As was observed in the aerial plant parts (< 12% of total bioavailable metals). The ability of kenaf to tolerate these metals and avoid phytotoxicity could be attributed to the stabilization of the metals in the roots and hence reduction of toxic metal mobility (TF < 1). With the application of leachate, kenaf was also found to have higher biomass and subsequently recorded 11% higher bioaccumulation capacity, indicating its suitability for phytoextraction of leachate contaminated sites.
Matched MeSH terms: Water Pollutants, Chemical/analysis; Water Pollutants, Chemical/pharmacology*; Water Pollutants, Chemical/chemistry
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.
Matched MeSH terms: Water Pollutants, Chemical/chemistry*