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A massive quantity of Elaeis guineensis (oil palm) trunk biomass, containing a significant amount of natural starch, is available in Malaysia as bio-waste because of annual replantation. The efficient extraction of this starch (carbohydrate polymer) would be worthwhile concerning the environmental sustainability and economy through conversion to bio-resources. This study investigated the effectiveness of the bisulphite steeping method for starch synthesis from oil palm trunk (OPT) bio-waste. The central composite design (CCD) of Design-Expert software executed an experimental model design, data analysis, evaluated the impacts of process variables and their interaction through response surface methodology to optimize the bisulphite steeping method for starch synthesis. The developed quadratic models for four factors (strength of sodium bisulphite solution, steeping hour, mixing ratio with the bisulphite solution and ultra-pure water) and one response (%Yield) demonstrated that a significant starch yield (13.54%) is achievable employing 0.74% bisulphite solution, 5.6 steeping hours, for 1.6 and 0.6 mixing ratio with the bisulphite solution and ultra-pure water respectively. Experimental outcomes were consistent with the predicted model, which eventually sustains the significance of this method. Malvern Zetasizer test revealed a bimodal granular distribution for starch, with 7.15µm of hydrodynamic size. Starch morphology was determined by scanning electron microscopy. X-ray diffraction investigation exhibits an A-type model, specifying persistent characteristics, while FTIR confirms the presence of hydroxyl, carboxylic, and phenolic groups like other cereal starches. Implication StatementMalaysia is the 2nd largest palm oil exporter of the world and produced 20.5 million metric tons of crude oil with 2.13 metric tons of palm kernel oil annually. Therefore, a massive quantity of palm oil trunk (OPT) biomass (110 million tons by 2020) is available annually as biowaste during the replanting activities. This huge volume of bio-waste is a severe environmental burden regarding the disposal issue. Modification of bio-wastes into a beneficial form (only 22% currently) would be sustainable for both the environment and the country's economy by diminishing the solid waste dumping challenges.Naturally OPT contains about 20% of lignin, 70% of cellulose, and a significant amount of starch, which is a is a carbohydrate polymer. Efficient extraction of starch from OPT bio-waste could ensure a potential reuse towards sustainable waste management and at the same time various application of starch i.e. as natural coagulant for wastewater and leachate treatment, food source, adhesive for particle boards etc.Even though several studies applied various methods for starch extraction from natural sources rather the current study aims to investigate the effectiveness of the novel bisulfite steeping method for the synthesis of natural starch from the OPT biomass and process optimization by applying the central composite design (CCD), from response surface methodology (RSM). The impacts and interaction of process variables were evaluated by RSM to optimize the starch yield. The developed quadratic model demonstrated that this method could achieve 13.54% starch yield, which is higher than previous studies.Therefore, implementation of this study outcomes will ascertain the reuse of OPT bio-waste reducing waste load from this sector and maximize the natural starch extraction for further implication of numerous economic activities.

In this study, the performance of limestone and anthracite coal filter media in treating Fe2+ adsorption from groundwater is evaluated. A breakthrough curve analysis is conducted to provide information on the prediction of operation life span and determine the break point and ineffective point of both filter media. The failure of both filter media as adsorbents can be measured through breakthrough curve analysis. Results show that limestone can receive Fe2+ loading at a concentration of 0.43 mg/L for a longer time (210 h) than that of anthracite (10 h). The breakpoint of the limestone column (40 h) is longer than that of the anthracite column (0.5 h). The performance of the breakthrough curve of both filter media is evaluated using Thomas, Yoon–Nelson and Adam Bohart models. The experimental data of both filter media reveal that the Yoon–Nelson and Thomas models contribute higher r2 to Fe removal than that of the Adam Bohart Model. Thus, the adsorption of Fe onto limestone and anthracite coal is influenced by interphase mass transfer and chemical reaction kinetics. Therefore, anthracite coal is not recommended as filter media because of its failure to function as a good filter medium and shorter life span than that of limestone.

Old landfill leachate is normally rich in colloidal particles, has low organic compound, poor biodegradability and hard to be biologically treated. The suspended particles are generally dispersed, ...

In this study, the response surface methodology (RSM) and artificial neural network (ANN) were employed to study the adsorption process of 2,4-dichlorophenoxyacetic acid (2,4-D) by using modified hydrogel, i.e., activated carbon poly(dimethylaminoethyl methacrylate) (AC/PDMAEMA hydrogel). The effect of pH, the initial concentration of 2,4-D and the activated carbon content on the removal of 2,4-D and adsorption capacity were investigated through the face-centered composite design (FCCD), optimal design and two-level factorial design. The response surface plot suggested that higher removal of 2,4-D and adsorption capacity could be achieved at the higher initial concentration of 2,4-D and lower pH and activated carbon content. The modeling and optimization for the adsorption process of 2,4-D were also carried out by different design methods of RSM and different training methods of ANN. It was found that among the three design methods of RSM, the optimal design has the highest accuracy for the prediction of 2,4-D removal and adsorption capacity (R2 = 0.9958 and R2 = 0.9998, respectively). The numerical optimization of the optimal design found that the maximum removal of 2,4-D and adsorption capacity of 65.01% and 65.29 mg/g, respectively, were obtained at a pH of 3, initial concentration of 2,4-D of 94.52 mg/L and 2.5 wt% of activated carbon. Apart from the optimization of process parameters, the neural network architecture was also optimized by trial and error with different numbers of hidden neurons in the layers to obtain the best performance of the response. The optimization of the neural network was performed with different training methods. It was found that among the three training methods of the ANN model, the Bayesian Regularization method had the highest R2 and lowest mean square error (MSE) with the optimum network architecture of 3:9:2. The optimum condition obtained from RSM was also simulated with the optimized neural network architecture to validate the responses and adequacy of the RSM model.

Ozonation, combined with suitable catalyst represents an interesting option in removing poorly degraded pollutants from stabilized landfill leachate. Therefore, this study aimed to eliminate chemic...

This study investigates the effectiveness of sludge in coagulation-flocculation treatment for suspended solids (SS) removal from landfill leachate using Tin (IV) chloride and Jatropha curcas seed (...

In the last three decades, pharmaceuticals research has increased tremendously to offer safe and healthy life, though it emerged as a new threat to the environment. These pharmaceutical residues pose a threat to the public health, and ecological balance, particularly in surface water located in agricultural catchments are facing more serious challenges. If these pharmaceutical residues left untreated could contaminate soil, water and may lead to serious outbreaks. However, many conventional treatments are integrated into wastewater treatment plants (WWTP’s), but there is a lack of dedicated treatment in eliminating pharmaceutical residues. Thus, dedicated on-site treatment at source (such as Hospitals and pharmaceutical industries) is essentially needed before discharging effluent to sewers or water bodies. Furthermore, the potential impact of pharmaceutical compounds even in trace concentration is more severe than the other pollutants present in the environment. In contrast, very limited knowledge about how such compounds and their kinetics directly impacts the environment and long-term impacts on humans. Traces of antibiotic compounds in the aquatic environment lead to resistant bacterial strains, exhibit threat to organisms and human health, hence affecting treatment. The recent literature reported that the pharmaceutical residues enter the environment in trace level. But, in long terms, these pharmaceuticals, even in trace concentration, has a potential threat to human health and terrestrial ecosystem. In this review article, we summarize the pharmaceutical residues potential to cause disease outbreaks in community and eco-toxicological impacts on aquatic organisms. Herein, we have reviewed the literature (1996–2020) to draw worldwide attention on rising pharmaceutical residues in the environment and associated impacts, disease outbreaks and eco-hazards.

This paper investigates the potential use of anthracite coal to remove Fe, Mn, UV254, and colour from pre-ozonated groundwater using batch experiment studies. Pre-ozonated groundwater samples were prepared in a laboratory to present the actual characteristics of groundwater samples. General characteristics for anthracite, as well as for groundwater samples, were examined. The influences of anthracite dosage, pH, agitation speed, and contact time on the reduction of tested parameters were discussed. Also, three adsorption isotherms (Langmuir, Freundlich, and Temkin), as well as kinetics models, were evaluated. Results demonstrated that the maximum removal of Fe (67%) occurred at 100 g of anthracite dosage, and no significant removal of Mn was observed. In addition, anthracite was capable of removing UV254 and colour using a dosage of 100 g. However, the maximum removal efficiency of colour was 76% using the same anthracite dosage of 100 g. The optimum shaking speed of 300 rpm resulted in the maximum removal efficiency of all parameters. The optimum pH was 7, which resulted in the maximum removal efficiency of Fe (40%), Mn (7%), UV254 (43%), and colour (50%). The optimum contact time was 90 min for all parameters with a dosage of 100 g which resulted in the removal efficiency of 54%, 52%, and 70% for Fe, Mn, UV254, and colour. The adsorption and kinetics models were well fitted with the experimental results. Overall, this study demonstrated that anthracite could be a good practical option for groundwater treatment. The strong iron (Fe) and manganese (Mn) concentrations; is one of the big groundwater issues, causing reddish and blackish in the groundwater. Batch experimental works have been undertaken to investigate the applicability of anthracite as an alternative adsorbent to remove Fe, Mn, UV254, and colour from pre-ozonated groundwater. The application of ozone alone was less effective to remove these pollutants. At the optimum pH value of 7 and 90 minutes of contact time, the adsorption and kinetics models were fit well with the experimental results. The study demonstrated that ozonation with anthracite could be a good practical option for groundwater treatment.

The performance of limestone and anthracite coal were evaluated for the removal of pollutants from groundwater. The physical and chemical properties of two filter materials were characterised through X-Ray diffraction (XRD), X-Ray fluorescence (XRF), field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR). XRD analysis showed that the main peaks of calcite (CaCO3) are the predominant phase of limestone, whereas quartz and graphite are the crystalline phase of anthracite coal. The presence of calcium oxide (CaO) as the major composition indicated that limestone demonstrates a good ability for cation exchange. FTIR spectrum analysis showed that the functional groups present on the limestone surface are mostly hydrophilic groups, and anthracite exhibits hydrophobic characteristic. Limestone has the potential to adsorb heavy metal pollutants, whereas anthracite has the capability to adsorb organic pollutants. Therefore, the two filter materials can be used as alternatives to remove pollutants in treating groundwater.

Hospital wastewater (HWW) is one of the largest sources of pharmaceutical release. The present paper proposes the sustainable and controllable hospital wastewater treatment method based on the phot...

The high-strength leachate produced from sanitary landfill is a serious issue around the world as it poses adverse effects on aquatic life and human health. Physio-chemical technology is one of the promising options as the leachate normally presents in stabilized form and not fully amendable by biological treatment. In this research, the effectiveness of natural zeolite (clinoptilolite) augmented electrocoagulation process (hybrid system) for removing high-strength ammonia (3,442 mg/L) and color (8,427 Pt-Co) from naturally saline (15 ppt) local landfill leachate was investigated. A batch mode laboratory-scale reactor with parallel-monopolar aluminum electrodes attached to a direct current (DC) electric power was used as an electrocoagulation reactor for performance enhancement purpose. Optimum operational conditions of 146 g/L zeolite dosage, 600 A/m2 current density, 60 min treatment time, 200 rpm stirring speed, 35 min settling duration, and pH 9 were recorded with up to 70% and 88% removals of ammonia and color, respectively. The estimated overall operational cost was 26.22 $/m3 . The biodegradability of the leachate had improved from 0.05 to 0.27 in all post-treatment processes. The findings revealed the ability of the hybrid process as a viable option in eliminating concentrated ammonia and color in natural saline landfill leachate. PRACTITIONER POINTS: Clinoptilolite was augmented on the electrocoagulation process in saline and stabilized landfill leachate (15 ppt). The high strength NH3 -N (3,442 mg/L) and color (8,427 Pt-Co) were 70% and 88% removed, respectively. The optimum conditions occurred at 140 g/L zeolite, 60 mA/cm2 current density, 60 min, and final pH of 8.20. The biodegradability of the leachate improved from 0.05 to 0.27 after the treatment. This hybrid treatment was simple, faster, and did not require auxiliary electrolyte.

This paper investigates the potential use of sequential treatment using ozonation–adsorption and adsorption–ozonation processes for stabilized landfill leachate treatment. Zeolite was used as adsorbent due to its novel composition of naturally hydrated aluminosilicate minerals. Preliminary tests were conducted to determine the optimum conditions of ozone and zeolite. Results demonstrated that the usage of ozonation as a post-treatment for adsorption could effectively remove 92%, 82%, and 75% of colour, COD, and NH4–N, respectively. In addition, the application of ozonation as a pre-treatment showed a good removal for colour, COD, and NH4–N with a removal efficiency of 93%, 80%, and 71%, respectively. Also, an improvement in biodegradability of the leachate was achieved after ozonation/adsorption and adsorption/ozonation which increases the BOD5/COD ratio from 0.016 to 0.195 and 0.194, respectively, where the maximum BOD5/COD in the raw leachate was 0.02. This is attributed to the oxidation of high molecular weight organics in the sample. A combined treatment leads to a removal of inorganic and small non-biodegradable organic molecules, which decreases the COD and further improve the BOD5/COD ratio. This study demonstrates that the application of ozonation as a pre- and post-treatment with zeolite is an effective treatment method that can improve the treatment of stabilized landfill leachate .

Landfills are the main option for waste disposal all over the world. Most of the landfill sites across the world are old and are not engineered well to prevent contamination of the underlying soil and groundwater by the toxic leachate. The present study examines the potential use of raw zeolite and heated activated zeolite in the reduction of COD, NH3-N, and colour from leachate. Zeolite was activated using different temperatures at 150 °C, 200 °C, and 250 °C for 3 h. General characterization was conducted for raw zeolite and heat-activated zeolite to investigate the influence of temperature on zeolite properties. Batch experiments were conducted at the optimum dosage of zeolite and pH. Results demonstrated that the optimum dosage of raw zeolite was 10 g with 53.1%, 22.5% and 46% reduction of NH3-N, COD, and colour, respectively. The optimum pH for NH3-N was 7 with a percentage removal of 55.8% while better reduction of COD and colour was obtained at pH 4 with a percentage removal of 24.3% and 73.8%, respectively. Also, the optimum temperature tested was at 150 °C, where the optimum dosage using activated zeolite heated at 150 °C was 10 g, resulted in the maximum reduction of NH3-N, COD, and colour of 45.1%, 11.8% and 43.7%, respectively. The optimum dosage of activated zeolite heated at 200 °C and 250 °C, which was 25 g. This indicates that the use of the activated zeolite heated at 150 °C can achieve the optimum removal at a lower cost which is applicable for a larger scale of wastewater treatment. In addition, it was found that the capacity of the zeolite before and after heat activation was 41.30 cmol/kg and 181.90 cmol/kg, respectively. The adsorption isotherm analysis reveals that both Freundlich and Langmuir isotherms were in agreement with experimental data. However, the Freundlich isotherm model was more favourable than Langmuir isotherm to evaluate the adsorption equilibrium of the three pollutants as verified by the high R2 values.

This paper investigates the suitability of limestone to attenuate Fe and Mn from pre-ozonated groundwater samples using batch study and fixed column bed. The effects of limestone dosage, shaking speed, contact time, and pH on the removal efficiency of Fe and Mn are discussed. Pre-ozonated groundwater samples were prepared to present actual samples from Pintu Geng water treatment plant. A general characterization for groundwater as well as for limestone was conducted. In addition, the breakthrough and exhaustion points for limestone were determined. Results showed that limestone has good potential to remove more than 90% of Fe and Mn at optimum dosage of 40 g. The removal percentage for both metals was also affected by changing the contact time, where the maximum removal of Fe and Mn was observed at 90 and 120 minutes, respectively, at pH 8 and shaking speed of 350 rpm. The breakthrough time and exhaustion time of Fe were 40 hours and 210 hours, respectively. However, faster breakthrough time (30 minutes) and exhaustion time (16 hours) were observed for Mn sorption. The findings showed that an integrated ozone-limestone adsorption process significantly enhanced the removal of Fe and Mn up to 99.5% and 92%, respectively.

The current review aims at improving the understanding on the treatment frameworks related to poultry slaughterhouse wastewater (PSWW) treatment efficiency. Technologies used for nutrient and organ...

Leachate generation is among the main challenging issues that landfill operators must handle. Leachate is created when decomposed materials and rainwater pass through the waste. Leachate carries many harmful pollutants, with high concentrations of BOD, COD, colour, heavy metals, ammoniacal nitrogen (NH3-N), and other organic and inorganic pollutants. Among them, COD, colour, and NH3-N are difficult to be completely eliminated, especially with a single treatment. They should be handled by appropriate treatment facilities before being safely released into the environment. Leachate remediation varies based on its properties, the costs of operation and capital expenditures, as well as the rules and regulations. Up until now, much scientific and engineering attention was given to the development of comprehensive solutions to leachate-related issues. The solutions normally demand a multi-stage treatment, commonly in the form of biological, chemical, and physical sequences. This review paper discussed the use of contemporary techniques to remediate landfill leachate with an emphasis on concentrated COD, colour, and NH3-N levels with low biodegradability that is normally present in old landfill or dumping grounds in developing countries. A semi-aerobic type of landfill design was also discussed, as this concept is potentially sustainable compared to others. Some of the challenges and future prospects were also recommended, especially for the case of Malaysia. This may represent landfills or dumpsites in other developing countries with the same characteristics.

Water shortage has been an issue for urbanized areas. For the Penang state in Malaysia, it is forecast that there will be a significant increase in water demand in the future. Penang authorities in Malaysia are trying to find an alternative water source to overcome the problem, with one of the options being the Perai River catchment. However, the river water quality was found to be polluted and not suitable to be used for water extraction for domestic consumption. This paper aims to study the pollution level variation due to changes in rainfall during the year in the Perai River Basin, and estimate the TMDL of the river in a particular case for BOD, COD, and NH3N parameters. A water quality model was developed for the Perai River, Jarak River and Kulim River using InfoWorks ICM. The year 2016 was selected as a model event due to data availability. BOD, COD and NH3N concentrations were used for TMDL calculation, and the load duration curve approach was used to estimate TMDL. The tidal effect at the downstream of the Perai River was found to impact the data analysis in the river stretch. It was found that pollutant load exceedance was the highest during the rainy season and the problematic pollutant was NH3N. Thus, local authorities need to focus on tidal and seasonal change factors when developing action plans to manage water quality issues in this basin.

This paper examines the environmental impact of the use of compacted sewage sludge:red gypsum (SS:RG) mixture as intermediate landfill cover in terms of yield and quality of leachate as characterised by hydraulic conductivity and leaching behaviour. A series of column tests using the constant head method is carried out by percolating the synthetic leachate through samples that have been compacted at various degrees (60, 70, 75, 80 and 85%). The leachate quality is monitored at pre-determined days for pH, COD, Cu, Fe and Zn. In general, hydraulic conductivity decreases in three stages, in which the first stage is mainly attributed to the particle rearrangement and hydration of calcium silicate hydrate (CSH). The hydration of CSH increases the pH, which causes the heavy metal to precipitate and be entrapped within the matrices of CSH gel, thereby further reducing the porosity and hydraulic conductivity. A minimum of 75% compaction has shown favourable final porosity, hydraulic conductivity, and leachate quality, although a minimum of 80% compaction is recommended in order to achieve a satisfactory compressive strength of greater than 345 kPa for a landfill operation.

Old leachate normally has a low organic compound content, poor biodegradability and is hard to biologically treat. The efficacy of tetravalent metal salts as a coagulant and the application of a natural coagulant as a flocculant in landfill leachate treatment is still inconclusive. Hence, this study aimed to evaluate the potential application of tin tetrachloride (SnCl4) as the main coagulant and the rubber seed (Hevea brasiliensis) (RS) as the natural coagulant aid as the sole treatment in eradicating highly coloured and turbid stabilised landfill leachate present at one of the old local landfills in Malaysia. The standard jar test conducted revealed that SnCl4 was able to eliminate 99% and 97.3% of suspended solids (SS) and colour, respectively, at pH8, with 10,000 mg/L dosages, an average particle size of 2419 d·nm, and a zeta potential (ZP) of −0.4 mV. However, RS was found to be ineffective as the main coagulant and could only remove 46.7% of SS and 76.5% of colour at pH3 with 6000 mg/L dosages, and also exhibited smaller particles (933 d·nm) with ZP values of −6.3 mV. When used as a coagulant aid, the polymer bridging mechanism in RS helped in reducing the SnCl4 concentration from 10,000 mg/L to 8000 mg/L by maintaining the same performances. The presence of 1000 mg/L RS as a coagulant aid was able to remove 100% of SS and 97.6% of colour. The study concluded that RS has the potential to be used together with SnCl4 in treating concentrated leachate with SS and colour.