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This paper discussed the experimental performance of a solar still with cylindrical hollow fins that were integrated to a black painted stainless-steel basin. The cover of the solar still was made of transparent polythene film, while the frame was made of polyvinyl chloride (PVC). Mild steel cylindrical hollow pipes of 0.035 m diameter were used as fins in the solar still. The performance of this solar still (PSSCHF) was compared with the performance of a conventional solar still (PSS1) which was made of similar fabrication materials, but without using fins in its basin. Each solar still basin contained water with the depth of 1 cm that was collected from a pond located at the Universiti Sains Malaysia (USM) campus. Both PSSCHF and PSS1 solar stills were exposed to similar climatic conditions within the same locality at USM during the experiments. The purpose of using the fins in the basin of PSSCHF was to absorb more heat from solar irradiance. The PSSCHF attained a maximum productivity of 4.49 L/m2.d, whereas the PSS1 obtained a maximum water production of 3.97 L/m2.d. The quality of fresh water produced from the solar stills met the World Health Organization potable water standards.

Polycyclic aromatic hydrocarbons (PAHs) are the toxic and persistent micro-pollutants recalcitrant to biodegradation. Photo-Fenton process is a commonly adopted advanced oxidation process. Advanced oxidation processes generate highly reactive hydroxyl radicals (OH·) which completely mineralise the organic contaminants. This study aims to find the efficiency of photo-Fenton oxidation process in the removal of PAHs and COD from landfill leachate, and investigate its effect on 16 PAHs according to their number of aromatic rings. Experiments were designed using central composite design, a module of response surface methodology (RSM) in the Design-Expert software. pH, Fe2+ concentration, H2O2 concentration, reaction time and UV intensity were the five experimental variables which were optimised and modeled successfully. The statistical analysis proved that all the variables have significant effect on the model. The value of R2 (0.94) showed a high reliability in the estimation of chemical oxygen demand and polycyclic aromatic hydrocarbons removal efficiency. Optimum experimental conditions of pH 6.5, Fe2+ 1.1 g/L, H2O2 concentration 5.5 g/L, reaction time 40 min and UV intensity 13.5 W resulted in the maximum chemical oxygen demand and polycyclic aromatic hydrocarbons removal efficiency of 84.43% and 92.54%, respectively. Validation was carried out by conducting additional set of experiments, and the small gap between observed and predicted values confirmed that central composite design is the effective tool to optimise the photo-Fenton oxidation process in the degradation of chemical oxygen demand and polycyclic aromatic hydrocarbons.

Sludge management is an integral process of an effluent treatment plant (ETP). This study aimed at using the electro-Fenton (EF) process for pretreatment of a cattle-based slaughterhouse ETP sludge to enhance biogas production from anaerobic digestion. EF-oxidation experiments were conducted in 0.5 L beakers with mild-steel electrodes, to study the effect of factors, viz., H2O2 concentration, current density and reaction time on soluble chemical oxygen demand (sCOD) concentration, soluble extracellular polymeric substances (sEPS) concentration and volatile suspended solids (VSS) removal efficiency. This was followed by the quantification of biogas production from the raw and pretreated sludge in anaerobic digestion (AD). Experimental conditions for the EF process were optimized using response surface methodology (RSM). At optimized experimental conditions, EF pretreatment resulted in an increase in sCOD and sEPS concentrations, from 0.91 g/L to 6.1 g/L and 0.18 g/L to 1.4 g/L, respectively. VSS removal efficiency was 68.1%. Batch anaerobic digestion studies demonstrated an enhancement in the specific biogas yield, from 110 NmL/g-VS to 460 NmL/g-VS.

In this paper, the synthesis, characterization, and comparative performance of Black-TiO2 and manganese-doped TiO2 (Mn-TiO2) nanoparticles for photocatalytic removal of phenolic compounds from agro-industrial effluent known as treated palm oil mill effluent (TPOME) are reported. The Black-TiO2 nanoparticles were synthesized via a green synthesis approach using a renewable chemical, glycerol as a reducing agent. The Mn-TiO2 nanoparticles were synthesized via the wet impregnation method using potassium permanganate (KMnO4) as a precursor. Experimental results revealed that both types of TiO2 nanoparticles, Black-TiO2 and Mn-TiO2 nanoparticles were anatase phase with a particle size range from 30–80 nm, improved visible light absorption and narrow bandgap of 2.96 and 2.12 eV, respectively. The improved visible light absorption was ascribed to the presence of Ti3+ defect states in Black-TiO2 nanoparticles and the substation of Mn into TiO2 matrix in Mn-TiO2 nanoparticles. The improved visible light absorption led to the enhanced photocatalytic performance of Black-TiO2 and Mn-TiO2 nanoparticles. The former was able to remove 48.17% whereas the latter removed 39.11% of 224.85 mg/L of phenolic compounds from TPOME under 180 min of visible light irradiation. The Black-TiO2 and Mn-TiO2 nanoparticles showed 2.2-fold and 1.7-fold higher performance, respectively, than the Pure-TiO2 nanoparticles. The Black-TiO2 nanoparticles exhibited superior photocatalytic performance, and the highest reaction rate constant (Kapp = 0.31127) was achieved which is two-fold higher than the one obtained by Pure-TiO2 nanoparticles (Kapp = 0.14733). The recyclability test showed that Mn-TiO2 nanoparticles were more stable indicated by their negligible loss (1.55%) of photoactivity after five repeated cycles.

Issues: Dye-containing wastewater not effectively managed is among the major contributors to water contamination. It is considered a major threat to public health and the environment. Thus, it must be handled properly before discharging into the environment. This chapter discusses the performance evaluation of the sequential batch reactor (SBR) system in managing dyes. It further complied and analyzed the impact of several environmental and operational parameters on the system in dye degradation. The various variables such as cycle time, hydraulic and sludge retention times, aeration, agitation, pH, dissolved oxygen, redox potential, feeding, temperature, hydrodynamic shear force, etc. are described. Major advances: Due to their complicated structure and synthetic root source, dyes are often regarded as one of the most difficult parts of textile wastewater to process. Environmental contamination emanating from toxic dye processing by dyeing industries continues to be a challenge. All through dye degradation, a variety of methods have been used, with various levels of efficacy, which may be attributable to differences in dye properties, discharge conditions, technical potentialities, regulatory obligations, and financial thoughtfulness. Recently, the usage of SBR in dye degradation has continuously received attention from scientists. It is widely preferred in dyes degradation because it is an efficient process. More so, taking advantage of the high SBR versatility, the control parameters can be changed appropriately and the decolorization potential can be recovered. Owing to its operational versatility, shock load resistance, and high biomass retention, this chapter emphasized SBR application and efficiency for dye treatment in the context of environmental conservation. The chapter further stressed the effects of environmental and operational parameters during dyes degradation. In recent decades, dye degradation has been successfully regulated by optimizing a lot of valuable environmental and operational parameters. They assist in the comprehension of bio-flocculation structure, properties, and mechanisms. These optimization strategies for environmental/operational parameters thus pave the route for the production of fewer by-products. The application of RSM to physicochemical dye degradation processes could result in better design and optimization. Researchers focusing on dye degradation, physicochemical processes, and RSM can find the outcome of this chapter extremely beneficial. Looking at the environmental aspect and considering the high content of hazardous intermediate metabolites found in dyes, the SBR system combined with other treatment technologies are more efficient for dye degradation. The content of this chapter is expected to improve readers’ fundamental literacy, direct research scholars, and be integrated into upcoming laboratory experiments on SBR systems for dye wastewater treatment.

In this study, palm oil mill effluent (POME) treated by ultrasonication at optimum conditions (sonication power: 0.88 W/mL, sonication duration: 16.2 min and total solids: 6% w/v) obtained from a previous study was anaerobically digested at different hydraulic retention times (HRTs). The reactor biomass was subjected to metagenomic study to investigate the impact on the anaerobic community dynamics. Experiments were conducted in two 5 L continuously stirred fill-and-draw reactors R1 and R2 operated at 30 ± 2 °C. Reactor R1 serving as control reactor was fed with unsonicated POME with HRT of 15 and 20 days (R1-15 and R1-20), whereas reactor R2 was fed with sonicated POME with the same HRTs (R2-15 and R2-20). The most distinct archaea community shift was observed among Methanosaeta (R1-15: 26.6%, R2-15: 34.4%) and Methanobacterium (R1-15: 7.4%, R2-15: 3.2%). The genus Methanosaeta was identified from all reactors with the highest abundance from the reactors R2. Mean daily biogas production was 6.79 L from R2-15 and 4.5 L from R1-15, with relative methane gas abundance of 85% and 73%, respectively. Knowledge of anaerobic community dynamics allows process optimization for maximum biogas production.

This work investigated the performance of two solar stills with similar polythene film cover and black painted stainless steel basin. One was a passive solar still and the other named active solar ...

The aim of this study was the production of high surface area activated carbon (AC) under optimized synthesis conditions from Mangosteen Peels (MP) waste using a single step ZnCl2 activation process. The influence of the various activation parameters such as impregnation ratio, impregnation time, carbonization time, and carbonization temperature on surface area and pore characteristics of synthesized AC was investigated. The AC prepared under optimized conditions showed BET surface area, average pore diameter, and total pore volume of 1621.8 m2/g, 4.4 nm, and 1.805 cm3/g, respectively. The optimized synthesis conditions were as follows: 1:4 impregnation ratio, 600 °C calcination temperature, and 30 min calcination time. The characteristics of the optimized AC were analyzed using nitrogen adsorption-desorption isotherm, scanning electron microscopy, pore structural analysis, Fourier transformed infrared spectroscopy and X-Ray diffraction analysis. The adsorption capacity of activated carbon prepared under optimized conditions for methylene blue was 1193 mg/g. Equilibrium data was best fitted to the Langmuir isotherm, while adsorption kinetics was favorably described by the pseudo-second-order kinetic model. The findings reveal the feasibility of mangosteen peel waste to be used as a potential and cheap precursor for the preparation of high surface area mesoporous AC.

Recent trends in adsorption of Chromium (Cr), Copper (Cu), Lead (Pb) and Mercury (Hg) in wastewater using (i) carbonaceous materials including activated carbon (AC) and biochar (BC), and (ii) nanomaterials including nano zero-valent iron (nZVI) and MXenes have been discussed in this paper. It has been found that adsorption capacity depends largely on the adsorbent modification technique, initial pH of wastewater, dosage of adsorbent, contact time and initial concentration of the pollutants. The pH value ranges for maximum removal of Cr, Cu, Pb and Hg have been reported as 2-4, 5-6, 5-8 and 3-8, respectively. Up to 99% removal of metals has been reported using AC, BC, nZVI and MXene. The mechanism involves the reduction and chemical adsorption of metals. AC and BC have a higher surface area (up to 5000 m

An alternative method of electrochemical oxidation was employed to degrade persistent compounds in the form of antibiotics using strong oxidizing agents such as hydroxyl ions. A 24 factorial design was employed to check the effect of four factors namely pH, current density, electrolysis time and electrolyte concentration set at their high (+) and low (-) levels on the antibiotics (amoxicillin, ciprofloxacin and erythromycin) degradation in water. The response was obtained in the form of COD (chemical oxygen demand) removal. A prediction model was developed to predict the values of COD removal. Later the main effect, contribution and interactions were studied with Design Expert Software 7.0. About 89.5% COD removal was obtained when pH and time were set at their high level and the other two factors at their low level. It was determined that the pH when set at high level (pH 9) had the most effect (24.68) and contribution (43.6) in the degradation process and hence the removal of COD. This technology of electrochemical oxidation can be employed in industries to efficiently remove pharmaceuticals, paints, dyes and other organic compounds.

Anaerobic digestion (AD) appears to be a popular unit operation in wastewater treatment plant to treat waste activated sludge (WAS) and the produced methane gas can be harvested as renewable energy. However, WAS could inhibit hydrolysis stage during AD and hence pre-treatment is required to overcome the issue. This paper aimed to study the effect of electrochemical pre-treatment (EP) towards efficiency of AD using titanium coated with ruthenium oxide (Ti/RuO2) electrodes. The investigation has been carried out using in-house laboratory batch-scale mesophilic anaerobic digester, mixed under manipulation of important operating parameters. Optimization was performed on EP using response surface methodology and central composite design to maximize sludge disintegration and dewaterability. By operating at optimal conditions (pH 11.65, total solids 22,000 mg/L, electrolysis time 35 min, current density 6 mA/cm2, and 1000 mg/L of sodium chloride), the pre-treated WAS in terms of mixed liquor volatile suspended solids (MLVSS) removal, soluble chemical oxygen demand (sCOD), capillary suction time (CST) reduction, and extracellular polymeric substance (EPS) were 38%, 4800 mg/L (increased from 935 mg/L), 33%, and 218 mg/L, respectively. Following AD, the volatile solids (VS) removal and chemical oxygen demand (COD) removal by EP were enhanced from 40.7% and 54.7% to 47.2% and 61.5%, respectively, at steady-state. The biogas produced from control and electrochemical pre-treated WAS were in the ranges of 0.12 to 0.17 and 0.2 to 0.24 m3/kg VSfed, respectively, and the volume of biogas produced was 44–67% over the control. Based on the results obtained, suitability of EP for WAS prior to AD was confirmed.

The potassium (K) and sodium (Na) elements in banana are needed for hydration reaction that can enhance the strength properties of concrete. This research aims (a) to determine the material engineering properties of banana skin ash (BSA) and concrete containing BSA, (b) to measure the strength enhancement of concrete due to BSA, and (c) to identify optimal application of BSA as supplementary cement materials (SCM) in concrete. The BSA characterization were assessed through X-ray fluorescence (XRF) and Blaine’s air permeability. The workability, compressive strength, and microstructures of concrete containing BSA were analysed using slump test, universal testing machine (UTM) and scanning electron microscope (SEM). A total of 15 oxides and 19 non-oxides elements were identified in BSA with K (43.1%) the highest and Na was not detected. At 20 g of mass, the BSA had a higher bulk density (198.43 ± 0.00 cm3) than ordinary Portland cement (OPC) (36.32 ± 0.00 cm3) indicating availability of large surface area for water absorption. The concrete workability was reduced with the presence of BSA (0% BSA: > 100 mm, 1% BSA: 19 ± 1.0 mm, 2%: 15 ± 0.0 mm, 3% BSA: 10 ± 0.0 mm). The compressive strength increased with the number of curing days. The concrete microstructures were improved; interfacial transition zones (ITZ) decreased with an increase of BSA. The optimal percentage of BSA obtained was at 1.25%. The established model showed significant model terms (Sum of Squares = 260.60, F value = 69.84) with probability of 0.01% for the F-value to occur due to noise. The established model is useful for application in construction industries.

Polycyclic aromatic hydrocarbons (PAHs) are mutagenic and carcinogenic contaminants made up of fused benzene rings. Their presence has been reported in several wastewater streams, including produced water (PW), which is the wastewater obtained during oil and gas extraction from onshore or offshore installations. In this study, ferrate (VI) oxidation was used for the first time for the treatment of 15 PAHs, with the total concentration of 1249.11 &mu, g/L in the produced water sample. The operating parameters viz., ferrate (VI) dosage, pH, and contact time were optimized for maximum removal of PAHs and chemical oxygen demand (COD). Central composite design (CCD) based on response surface methodology (RSM) was used for optimization and modeling to evaluate the optimal values of operating parameters. PAH and COD removal percentages were selected as the dependent variables. The study showed that 89.73% of PAHs and 73.41% of COD were removed from PW at the optimal conditions of independent variables, i.e., ferrate (VI) concentration (19.35 mg/L), pH (7.1), and contact time (68.34 min). The high values of the coefficient of determination (R2) for PAH (96.50%) and COD (98.05%) removals show the accuracy and the suitability of the models. The results showed that ferrate (VI) oxidation was an efficient treatment method for the successful removal of PAHs and COD from PW. The study also revealed that RSM is an effective tool for the optimization of operating variables, which could significantly help to reduce the time and cost of experimentation.

Antibiotics are considered emerging contaminants that may cause substantial detrimental effects on the environment. The severe threat is the development of antibiotic resistance due to its frequent consumption. This review presents the feasibility of anaerobic digestion (AD) in eliminating antibiotics and antibiotic-resistant genes (ARGs) from the environment. This review concludes that anaerobic membrane bioreactor (AnMBR) is the most productive technology for antibiotics (sulfamethoxazole, sulfadiazine, trimethoprim, clarithromycin, erythromycin, ciprofloxacin, ofloxacin, cefalexin, cephradine) and ARGs removal (sul1, sul2, tetO, tetW, ermF, ermB, blaNDM-1, blaCTX-M-15, blaoxa-48, blaoxa-1). Inhibition to AD in terms of biogas or methane production upon antibiotics exposure has been observed for sulfamethoxazole (>25 mg/l), tetracycline (>1 mg/l), ofloxacin (>10 mg/l), ciprofloxacin (>80 mg/l), sulfamerazine (>90 mg/l), tylosin (>130 mg/l) and ceftiofur (>10 mg/l). This review also fortifies those microorganisms belonging to phylum Proteobacteria, Firmicutes, Chloroflexi, Bacteroidetes, Thermotogae, Euryarchaeota, Elusmicrobia, Chlorobi, Spirochaetes, Synergistetes, and Actinobacteria are important for stable performance of AD in terms of antibiotics removal and bioenergy production. However, the effects of antibiotics (individual and combined) on bioenergy production and microbial compositions have not been extensively investigated for AnMBR. Thus, further research must focus on these research gaps. In addition, AnMBR can be integrated with microbial fuel cells (MFCs) to enhance antibiotics and ARGs removal and mitigate membrane fouling issues while simultaneously producing bioelectricity and chemicals. Hence, future studies must examine their combined performance for antibiotic wastewater treatment. Additionally, mesophilic and thermophilic anaerobic digesters are exceptional in eliminating major ARGs (tetracyclines, sulfonamides, macrolides, fluoroquinolones, trimethoprim, beta-lactamase, aminoglycosides, florfenicol) from both biosolids (sludge) and manure. Nevertheless, forthcoming research must investigate their combined performance especially by using activated carbon and nano zero-valent iron (NZVI) in eliminating ARGs and enhancing bioenergy production.

In order to retain a high concentration of activated sludge in the wastewater treatment plant, the dense activated sludge is entrapped into the polyvinyl alcohol (PVA) cryogel beads. For protecting the entrapped activated sludge biomass from the inhibitory effect exerted by recalcitrant pollutant, i.e., 4-chlorophenol (4-CP), the novel PVA cryogel beads with external surface covered by the powdered activated carbon (PAC) were successfully synthesized in this study. The synthesis was achieved by extruding the biomass-PVA polymeric matrix into the gelatin solution containing PAC. The maximum PAC density on the external surface of cryogel beads was calculated to be in the range of 938–978 mg/m2. The PAC distributed on the external surface of cryogel beads was found to possess a higher 4-CP adsorption capacity than the beads with homogenized PAC. These cryogel beads were also capable of shielding the activated sludge biomass entrapped within beads from being directly exposed to the inhibitory effect of 4-CP via adsorption by PAC distributed on the external surface. Thus, only low concentration of 4-CP was diffused into the beads and biodegraded to achieve a total removal of 4-CP. This beneficial effect was later confirmed could last for more than 20 cycles of uses in removing 4-CP via the simultaneous adsorption and biodegradation processes.

Used engine oil (UEO) is recognized as a hazardous waste produced during engine servicing. Its disposal in an environmentally friendly manner is a big challenge. This paper presents the experimental results of an investigation of the effects of UEO on slump and hardened concrete properties. Three concrete groups; 100% cement (OPC) concrete, concrete with 60% OPC + 40% fly ash and concrete with 80% OPC + 20% rice husk ash were prepared. Each of the groups composed of a control mix and a mix with 0.15% dosage of UEO (this dosage was selected from previous studies). Slump measurement of fresh concrete confirmed that a small dosage of UEO reasonably improves the slump of concrete. Lignosulfonate molecule (a common class of water reducing admixture) consists of aromatic rings containing one of the ionic groups viz., OH−, COO−, SO32−. The chemical composition of used engine oil showed the presence of 37% SO3 content that may be the reason for the plasticizing effect. Used engine oil caused variation in the compressive strength in the range of ±20% as compared to the control mix. The compressive strength at 28, 56, and 180 days of 100% OPC concrete with UEO reduced by about 17%. In general, a small dosage of used engine oil caused a substantial reduction in coefficient of oxygen permeability and porosity of all concrete mixes, which is an indicator of enhanced long-term durability.

The construction sector is among the fastest growing sectors in Malaysia; it consumes a vast amount of natural resources and produces a massive volume of construction and demolition waste. The waste is collected in a decentralised manner by sub-contracted companies. It is challenging to obtain reliable information on the amount of construction waste generated, because it is hard to determine its exact quantity and composition. Therefore, this study proposes a quantitative construction waste estimation model for residential buildings according to available data collected from the Construction Industry Development Board, Malaysia. In the development of this model, a theoretical investigation of the construction procedure and the construction waste generation process was conducted. The waste generated rate was determined as 25.79 kg m−2 for new residential constructions, which translates into about 553,406 t of anticipated waste annually.

In this study IrO2 (Iridium oxide) was coated onto a titanium plate anode from a dilute (50 mg/10 ml) IrCl3×H2O salt solution. Coating was done at high temperature (550∘C) using thermal decomposition. Surface morphology and characteristics of coated surface of Ti/IrO2 anode were examined by FESEM and XRD. The coated anode was applied for electrochemical removal of organic pollutants from synthetic water samples in 100 mL compartment of batch electrochemical cell. About 50% COD removal was obtained at anode prepared with low Ir content solution while 72% COD removal was obtained with anode prepared at high Ir content. Maximum COD removal was obtained at 10 mA/cm2 current density.

Palm oil mill effluent (POME) is a complex wastewater that consists of high concentration of chemical oxygen demand (COD) and insoluble organic solids. Anaerobic digestion has been successfully used in treating POME due to its low cost and ability to produce biogas. Nevertheless, biogas production can be enhanced by increasing the solubility of organic compounds during anaerobic treatment. To improve organic matter solubilization in POME, this study focuses on investigating the applicability of low frequency ultrasonication as a pretreatment to anaerobic digestion. Experiments were statistically designed by central composite design (CCD) and response surface methodology (RSM) was used to examine the impacts of independent variables (i.e., ultrasonication density, ultrasonication time and total solids concentration) on treatment performance in terms of organic matter solubilization and concentration of soluble chemical oxygen demand (SCOD). Analysis of variance (ANOVA) showed both models to be significant with Prob > F

Recently, research interest has shifted to the development of effective remediation technologies for treated palm oil mill effluent (TPOME) due to the failure of the existing treatment methods to comply with the standard discharge limits. Photocatalytic technology has been recognized as an extremely attractive and sustainable technology for the remediation of TPOME. However, inefficient harvesting of visible or solar light, very low remediation efficiency under visible light, incomplete recovery of the photocatalyst after the treatment, lack of property-performance relationship, and lack of process understanding as well as parametric optimization are the major challenges which hinder the practical application of photocatalytic technology for the remediation of TPOME. Many investigations have been carried out to overcome the existing challenges and enhance the overall remediation efficiency of TPOME. This review provides an in-depth and critical analysis of the recently developed strategies to countermeasure the limitations and improve the overall performance of photocatalytic technology for the remediation of TPOME with respect to the preparation of visible light active photocatalyst, strategies to eliminate the need for the recovery of photocatalyst, and parametric optimization of the photocatalytic process. Various properties of the photocatalysts were reviewed and their correlation with the photocatalytic performance for the remediation of TPOME was evaluated. Also, the specific removal rate (mg of COD removed/g catalyst h) was calculated to provide an inclusive and quantitative comparison of individual studies using various photocatalysts, which are barely deliberated in the published literatures. Prospective research needs for resolving the major challenges and improving the competency of photocatalytic technology for practical application in remediation of TPOME are suggested accordingly. This review will enhance our understanding of the photocatalytic technology for the remediation of TPOME and extend the boundary towards the practical application of this technology on an industrial scale.

This study was conducted to explore the effectiveness of tea waste (TW) biochar (BC) as an adsorbent for the oxidizable organic contaminants measured as chemical oxygen demand (COD) in produced water (PW). BCs were prepared by modifying the TW with single (pre-pyrolysis) and combined (pre and post pyrolysis) treatments using phosphoric acid and hydrogen peroxide solutions. Based on FTIR, XPS, XRD and BET characterizations, the combined modified BC had higher oxygen-containing functional groups (-OH and -COOH), surface area (82 ± 0.50 m2/g) and pore volume (0.08 ± 0.001 cm 3/g) compared to single modified BC (60 ± 0.50 m2/g, 0.02 ± 0.002 cm 3/g). The Langmuir monolayer adsorption model best fitted both BCs with separation factor R L