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Landfill leachate can threaten the environment and human life. Therefore, this study aims to investigate the efficiency of ozone (O3 ), O3 with zirconium tetrachloride (O3 /ZrCl4 ) and O3 with tin tetrachloride (O3 /SnCl4 ) in remediating the stabilised anaerobic landfill leachate (SAL) from Alor Pongsu, Perak. Hydroxyl radical (OH•) is an important oxidising agent in the ozonation process. Its presence was tested using tert-Butyl alcohol. Results showed that using ZrCl4 and SnCl4 in ozonation boosted the generation of hydroxyl radical, thereby enhancing the oxidation process and pollutant removal inside the sample. The O3 /ZrCl4 mix at chemical oxygen demand (COD) to ZrCl4 ratio of 1:1.5, pH 8-9 and 90 min reaction time resulted in the highest reduction rates of COD and colour at 91.9% and 99.6%, respectively. All results demonstrated that the optimum performance occurred at alkaline conditions (pH > 8), proving that OH radicals primarily oxidised the pollutants through an indirect reaction pathway. The biodegradability (biochemical oxygen demand/COD) ratio was also considerably improved from 0.02 (raw) to 0.37 using O3 /ZrCl4 , compared with using O3 alone and using O3 /SnCl4, which only recorded 0.23 and 0.28, respectively, after the treatment. The study demonstrated that O3 /ZrCl4 was the most efficient combination.

This study was conducted to evaluate the effect of the toxicity levels of the coagulation and flocculation process on raw and treated leachate using acute toxicity tests. Tin tetrachloride (SnCl4 ) and the Jatropha curcas (JC) seed was used as coagulant and coagulant aid to remove concentrated Suspended Solids, SS (534 mg/L), colour (19,297 Pt-Co), and Chemical Oxygen Demand COD (4,188 mg/L) in a stabilised landfill leachate. The toxicity effects on local red tilapia fish (Oreochromis niloticus) were investigated, which involved three main steps, namely acclimatisation, range-finding test, and short-term definitive test. The presence of JC seed (0.9 g/L) as a flocculant reduced the dosage of SnCl4 from 11.1 to 8.5 g/L and exhibited good removals of 99.78, 98.53, and 74.29%, respectively, for SS, colour, and COD. The toxicity test indicated that only 5 fishes died in the first 12 hours for the treated sample compared to 7 deaths for untreated leachate. In 96 hours, a total of 42 and 31 mortality rates were noted for the raw and treated leachate samples, respectively. The treated sample could reduce the toxicity effects to the tested tilapia fish and is safe to be discharged at appropriate dilution concentrations.

The removal of concentrated colour (around 5039 Pt–Co) and chemical oxygen demand (COD; around 4142 mg L−1) from matured landfill leachate through a novel combination of humic acid extraction and coagulation with natural oil palm trunk starch (OPTS) was investigated in this study. Central composite design from response surface methodology of Design Expert-10 software executed the experimental design to correlate experimental factors with desired responses. Analysis of variance developed the quadratic model for four factors (e.g. coagulant dosage, slow mixing speed and time and centrifugation duration) and two responses (% removal of colour, COD). The model confirmed the highest colour (84.96%) and COD (48.84%) removal with a desirability function of 0.836 at the optimum condition of 1.68 g L−1 coagulant dose, 19.11 rpm slow mixing speed, 16.43 minutes for mixing time and 35.75 minutes for centrifugation duration. Better results of correlation coefficient ( R2 = 0.98 and 0.96) and predicted R2 (0.94 and 0.84) indicates the model significance. Electron microscopic images display the amalgamation of flocs through bridging. Fourier transforms infrared spectra confirmed the existence of selected organic groups in OPTS, which eventually signifies the applied method.

Stabilised leachate usually contains lower concentration of organic compounds than younger leachate; it has low biodegradability and generally unsuitable for biological treatment. The effectiveness of tetravalent metal salts in a coagulation-flocculation (C–F) process is still inclusive. Application of natural coagulants as an alternative to the chemical could reduce chemical usage, is less costly, and environmentally friendly. Hence, the objective of the current research is to examine the possibility of reducing the amount of Tin (IV) chloride (SnCl4) as a primary coagulant by adding Jatropha curcas (JC) as a flocculant as a sole treatment through the C–F process in treating concentrated suspended solids (SS) (547 mg/L), colour (19,705 Pt–Co) and chemical oxygen demand (COD) (4202 mg/L) in stabilised landfill leachate. The work also aims to evaluate the sludge properties after treatment. Functional groups, such as carboxylic acids, hydroxyl and amine/amino compounds (protein contents), were detected in the JC seed to facilitate the C–F process by neutralising the charge pollutant in water and cause the possibility of hydrogen bonding interaction between molecules. The combination of JC seed (0.9 g/L) as a flocculant reduced the dosage of SnCl4 as a coagulant from 11.1 g/L to 8.5 g/L with removals of 99.78%, 98.53% and 74.29% for SS, colour and COD, respectively. The presence of JC improved the sludge property with good morphology; the particles were in a rectangular shape, had clumps and strong agglomeration. These properties of sludge proved that JC seed could enhance the adsorption and bridging mechanism in the C–F procedure.

Severe environmental pollution could occur in water bodies which serve as the discharge sites for improperly treated palm oil mill effluent (POME). This is because POME increases the chemical oxygen demand (COD) and suspended solids (SS) of the water body. This issue is addressed by investigating the use of raw and calcined limestone (800 °C) in a horizontal roughing filter to eliminate SS from POME in this work. The horizontal roughing filter was designed using various sizes of limestone (4 mm, 12 mm, and 20 mm) at various filtration rates (20, 60, and 100 mL/min). In order to model the experimental design, a method achieving ideal process conditions and optimum values of process variables, central composite design (CCD), and response surface methodology (RSM) were employed. From the column study conducted, a higher SS removal (75%) was obtained at a lower flow rate together with a smaller-sized (4 mm) calcined limestone (LS). The statistical analysis produced an SS removal model with considerable probability values (0.000). The Langmuir and Freundlich isotherms were also used to characterize the adsorption equilibrium during the removal of SS. However, the Langmuir isotherm proved to best fit the data.

Water pollutant removal by biomass adsorbent has been considered innovative and cost-effective, and thus commendable for application in industry. However, certain important aspects have been overlooked by researchers, namely the efficiency in the operation time and pollutant removal. In this research, landfill leachate samples with organic components were treated using a bentonite-enriched sawdust-augmented sequencing batch reactor (SBR) process. By modifying the pH, the sawdust samples were categorized into three groups: the acidic, the alkaline, and the neutral. To bentonite samples, the pH-adjusted sawdust was added at 10%, 20%, and 30% amounts by mass, respectively. At the optimum aeration rate of 7.5 L/min and contact period of 22 h, the treatment achieved 99.28% and 95.41% removal of chemical oxygen demand (COD) and NH3-N with bentonite, respectively. For both pollutants, in the presence of sawdust, the removal was only reduced by about 17% with the contact period reduced to 2 h, which was a considerable achievement.

Wastewater treatment is a key challenge in the textile industry. The current treatment methods for textile wastewater are insufficient or ineffective for complex dyes generated from the textile industry. This study evaluated the performances of two novel inorganic coagulants with high cationic charges, namely, titanium tetrachloride (TiCl4) and zirconium tetrachloride (ZrCl4). They were utilised to treat textile industry wastewater. Both coagulation processes were performed under the same experimental operational conditions. Turbidity, suspended solids (SS), colour, chemical oxygen demand (COD) and ammonia were measured to assess the efficiencies of the coagulants. Results indicated that ZrCl4 and TiCl4 exhibited high potentials for textile wastewater treatment. ZrCl4 presented high removal efficiency in COD and SS, whereas TiCl4 showed excellent removal in ammonia. Keywords: Textile wastewater, Coagulation, Titanium tetrachloride, Zirconium tetrachloride

A large volume of concentrated leachate is generated from leachate treatment via reverse osmosis. Concentrated leachate is a dark brown solution with high levels of pollutants. Treating concentrated leachate is extremely difficult, and thus, a combined treatment system is suggested. In the present study, concentrated landfill leachate was treated using a combined treatment technique that included electro-ozonation and a composite adsorbent augmented sequencing batch reactor (SBR) process. Central composite design and response surface methodology were utilized to investigate experimental data. Reaction time (30–120 min) and ozone concentration (40–120 mg/L) were selected as the independent variables. At an optimum reaction time (96.9 min) and ozone dosage (120.0 mg/L), the removal efficacies of chemical oxygen demand (COD), color, and nickel were 64.8%, 90.4%, and 52.9%, respectively, at original pH (7.3), as well as current and voltage of 4 A and 9 V, respectively. Ozone utilization ranged from 0.3 kg to 1.4 kg COD removed per kg ozone consumed. After treatment at optimum electro-ozonation performance, concentrated leachate was transferred to the powdered composite adsorbent (P-BAZLSC) augmented SBR reactor (PB-SBR). PB-SBR improved the removal efficiency for COD, color, and nickel from 64.8% to 88.2%, from 90.4% to 96.1%, and from 52.9% to 73.4%, respectively.

Recycled paper mill effluent (RPME) contains high levels of organic and solid compounds, causing operational problems for anaerobic biological treatment. In this study, a unique modified anaerobic inclining-baffled reactor (MAI-BR) has been developed to treat RPME at various initial chemical oxygen demand (COD) concentrations (1000–4000 mg/L) and hydraulic retention times (HRTs) (3 and 1 day). The COD removal efficiency was decreased from 96 to 83% when the organic loading rate (OLR) was increased from 0.33 to 4 g/L day. Throughout the study, a maximum methane yield of 0.25 L CH4/g COD was obtained, while the pH fluctuated in the range of 5.8 to 7.8. The reactor performance was influenced by the development and distribution of the microbial communities. Based on the next-generation sequencing (NGS) analysis, the microbial community represented a variety of bacterial phyla with significant homology to Euryarchaeota (43.06%), Planctomycetes (24.68%), Proteobacteria (21.58%), Acidobacteria (4.12%), Chloroflexi (3.14%), Firmicutes (1.12%), Bacteroidetes (1.02%), and others (1.28%). The NGS analysis showed that the microbial community was dominated by Methanosaeta concilii and Candidatus Kuenenia stuttgartiensis. This can be supported by the presence of filamentous and spherical microbes of different sizes. Additionally, methanogenic and anaerobic ammonium oxidation (ANAMMOX) microorganisms coexisted in all compartments, and these contributed to the overall degradation of substances in the RPME.

Coagulation behaviour of titanium tetrachloride (TiCl4) was investigated to treat leachate from Alor Pongsu landfill in regard to reduction in suspended solids (RSS), colour (Rc) and chemical oxygen demand (RCOD) and heavy metals. The studied factors were including pH (4, 7 and 10), TiCl4 dosage (800 mg/L, 1000 mg/L and 1200 mg/L) and chitosan dosage (0 mg/L, 250 mg/L and 500 mg/L). The results indicated that the highest RSS was 92.02 % at the pH 4, 1200 mg/L of TiCl4 and without chitosan addition. Furthermore, highest RC was 82.80% at experimental condition of 1200 mg/L TiCl4 and 500 mg/L chitosan with pH 4, while highest RCOD of 71.92 % was achieved at the same condition but pH 10. The produced sludge was characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) equipped with Energy Dispersive X-Ray (EDX). The results of this study indicated that TiCl4 is a promising coagulant for wastewater treatment.

This paper investigates the response of sewage sludge and red gypsum mixture under different compaction degree conditions in terms of hydraulic conductivity and unconfined compressive strength (UCS). The UCS and hydraulic conductivity assessments were undertaken using UCS machine and column test using the constant head method, respectively. Five samples were compacted to various degree of compaction (60, 70, 75, 80 and 85%) and percolated with distilled water for six months. The leachate samples from the column test were collected and analyzed at pre-determined days of 1, 3, 7, 14, 28, 42, 56, 75, 90, 120, 150 and 180. The UCS of samples increased with increasing degree of compaction, attributed to the increased number of contact and interparticle interaction between the particles. The degree of compaction appears to affect the initial hydraulic conductivity for the first three days of the experiment, however, gradually stabilize at 10-6 cm/s after 75 days for all samples. The concentration of leached metals and chemical oxygen demand (COD) is below the regulated limit that could affect the environment. The recommended degree of compaction is beyond 80% to achieve the required compressive strength of 345 kPa.

The aim of this study is to investigate the performance of combined solar photo-catalyst of titanium oxide/zinc oxide (TiO2/ZnO) with aeration processes to treat petroleum wastewater. Central composite design with response surface methodology was used to evaluate the relationships between operating variables for TiO2 dosage, ZnO dosage, air flow, pH, and reaction time to identify the optimum operating conditions. Quadratic models for chemical oxygen demand (COD) and total organic carbon (TOC) removals prove to be significant with low probabilities (

The current study investigated the performance of combined ozonation and zirconium tetrachloride (ZrCl4) for an anaerobic stabilized landfill leachate treatment. The effectiveness of ZrCl4 dosage [COD0/ZrCl4 ratio (g/g)], pH variation, and reaction time during ozonation were evaluated to obtain the optimal operational conditions of ozone (O3)/ZrCl4 oxidation process. The maximum removal efficiencies for chemical oxygen demand (COD) and color were 88 and 100 %, respectively, at 1/2 g zirconium tetrachloride dosage (COD0/ZrCl4), pH 6, and 90 min reaction time, whereas 79 % removal for ammonia (NH3–N) was obtained at pH 11. Biodegradability (BOD5/COD) was improved from 0.07 to 0.09 and 0.34 after treatment with O3 alone and O3/ZrCl4, respectively. Treatments using ozonation alone and zirconium alone were performed and compared with the results obtained from the treatment with the new catalytic ozone method (O3/ZrCl4). The new oxidation method (i.e., O3/ZrCl4) obtained better removal efficiencies for organic substances and ammonia and this method reported better biodegradability ratio compared with other related processes. The O3/ZrCl4 process is also more efficient than O3/Fenton and O3/persulfate for stabilizing leachate treatment.

Industrial wastewater has often shown to pose a serious environmental threat if not properly treated before discharges. In a similar vein, textile wastewater may degenerate the environment due to the high content of chemical substances, suspended solids and a very conspicuous intense color among other things. An attempt has therefore been made in this study to classically optimize the removal of color, suspended solids (SS) and chemical oxygen demand (COD) using natural clinoptilolite (CPL). By applying 8 g of CPL of (75–250) μm particle sizes, at a low and acidic pH of 2–3, for 100 min contact time and agitation of reaction at 150 rpm, the pollutant removals were: 89% of color, 90% of SS and 79% of COD. However, a very negligible increase in color, only up to 90% (i.e., less than 1%), but a reasonable removal in SS (up to 96%) was obtained when the media dosage was increased to 10 g. The kinetics of the adsorption of pollutants was studied.

In this study, a sequential batch reactor (SBR) with different types of fibers was employed for the treatment of poultry slaughterhouse wastewater. Three types of fibers, namely, juite fiber (JF), bio-fringe fiber (BF), and siliconised conjugated polyester fiber (SCPF), were used. Four SBR experiments were conducted, using the fibers in different reactors, while the fourth reactor used a combination of these fibers. The treatment efficiency of the different reactors with and without fibers on biochemical oxygen demand (BOD), chemical oxygen demand (COD), ammonia-nitrogen (NH3-N), phosphorus (P), nitrite (NO2), nitrate (NO3), total suspended solids (TSS), and oil-grease were evaluated. The removal efficiency for the reactors with fibers was higher than that of the reactor without fibers for all pollutants. The treated effluent had 40 mg/L BOD5 and 45 mg/L COD with an average removal efficiency of 96% and 93%, respectively, which meet the discharge limits stated in the Environmental Quality Act in Malaysia.

In this study, three start-up techniques of modified anaerobic inclining-baffled reactor (MAI-BR) were performance to understand the effect of inoculum source and effluent recycle on the treatment of recycled paper mill effluent (RPME). Flocculant anaerobic sludge from a palm oil mill pond and digested anaerobic sludge from a sewage treatment plant were inoculated in the first and second start-up/phase1, respectively. Results show that high chemical oxygen demand (COD) removals of 93 and 88% were achieved in the first and second start-up/phase1, respectively. The amount of methane produced in the second start-up/phase1 within 15 d was doubled as compared to the amount produced in the first start-up, with a higher methane content of 79% (as compared to 62% in the first start-up). This result indicated that the inoculum source has a significant effect on the reactor performance. The results in the second start-up/phase2 also showed that COD removal and methane production increased up to 94% and 0.52...

This study was carried out to compare the performance of different oxidation processes, such as solar photo-Fenton reaction, solar photocatalysis by TiO2, and the combination of the two for the treatment of petroleum wastewater from Sohar Oil Refinery by a central composite design with response surface methodology. The degradation efficiency was evaluated in terms of chemical oxygen demand (COD) and total organic carbon (TOC) reductions. Solar photocatalysis by the TiO2/Fenton method improved the performance of the photocatalyst at neutral pH for petroleum wastewater without the need to adjust the pH during this treatment. Under acidic conditions, the solar photo-Fenton process is more efficient than solar TiO2photocatalysis while it is less efficient under alkaline conditions. The TiO2dosage and pH are the two main factors that improved the TOC and COD reductions in the solar photocatalysis using combined TiO2/Fenton and the solar TiO2photocatalysis processes while the pH and H2O2concentration are the two key factors that affect the solar photo-Fenton process.

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.

Landfill leachate generation is one of the main problems from sanitary landfill. Chemical oxygen demand (COD), ammoniacal nitrogen (NH3-N), and color are among the most problematic parameters in stabilized leachate. In this regard, dedicated treatment facilities are required before leachate can be discharged into the environment. The performance of the combined ozonation (O3) and zirconium tetrachloride (ZrCl4) to treat two types of stabilized leachate was investigated during this study. Leachate samples were collected from an anaerobic stabilized leachate (Alor Pongsu Landfill Site, APLS) and semi-aerobic stabilized leachate (Pulau Burung Landfill Site, PBLS). Zirconium tetrachloride dosage was determined as 1 g/1 g (COD/ZrCl4 ratio) and then added to the leachate samples with 60 min ozonation at natural leachate pH (8). COD, color, and NH3-N were removed from the APLS sample at 33%, 70%, and 53% rates, respectively, whereas 48%, 75%, and 69%, respectively, from the PBLS samples. Ozone consumption was also calculated with the highest value (3.81 Kg O3/ Kg COD) reported in PBLS, whereas the lowest value (2.32 Kg O3/ Kg COD) was reported in APLS. Biodegradability of (BOD5/COD) was investigated and improved from 0.07 to 0.08 for the APLS samples and 0.05 to 0.11 for the PBLS samples after leachate oxidation. Results showed that the performance of O3/ZrCl4 oxidation is more efficient in treating semi-aerobic stabilized leachate than anaerobic stabilized leachate Moreover, the combined method proved to be more efficient in remediating leachate compared with ozone and zirconium treatment alone.

This study evaluated the performance of sequencing batch reactor (SBR) with and without the fibers of poultry slaughterhouse wastewater (PSWW). The fibers act as attachment materials to the suspended solids, which are considered as pollutant in PSWW. PSWW contains high-pollutant concentrations. Experiments were conducted using two 60 L laboratory SBR reactors at room temperature (25 °C) and pH 7±0.5. The removal percentage of SBR with and without the fibers was compared in terms of chemical oxygen demand and biological oxygen demand. The removal percentage of SBR with fibers showed higher overall performance, which was approximately 90%. Meanwhile, the removal of SBR without fibers achieved an average percentage of about 70%, which was slightly lower compared with SBR reactor with fibers.

At the ambient temperatures, the influence of operating conditions on persulfate (S2O8) oxidation of real textile wastewater was investigated for the removal of color, suspended solids (SS) and chemical oxygen demand (COD). The effects of oxidant dosage, initial solution pH and contact time were studied in a series of batch experiments using persulfate (PS) oxidant as sodium persulfate. Oxidant dose was defined by an oxidant/contaminant (PS/COD) molar ratio, varied from 1/1-10/1. Although parameter removals increased with the oxidant dose, especially for color and SS, a PS/COD molar ratio of 4/1 (6720mg/L) was adopted in a bid to use fewer chemicals. The pH was varied from 2-11, with pH of between 2 and 3 being the optimum. At 360minutes contact time, the removals of color, SS and COD were 84%; 71% and 32% respectively. Although relatively effective, especially for color removal, results show that the reactions might have been inhibited at ambient temperatures as shown by the particularly low removal of COD.

As textile wastewater is a major source of surface water pollutants when not sufficiently treated prior to discharge, strict disposal regulations were set and monitored by environmental authorities. As such, continuous research is necessary in textile wastewater remediation. In this study, real textile wastewater samples were directly collected from the wastewater discharge point of a manufacturer in Prai, Malaysia. Various particle sizes of clinoptilolite were applied to treat the wastewater in a series of batch experiments at a predetermined dosage, pH, and contact time. Removal of three main parameters [i.e. color, suspended solids (SS), and chemical oxygen demand (COD)] was monitored. The removal rates of color, SS, and COD were 47.9, 48, and 37.4%, respectively, at particle sizes larger than 2 mm and then increased to 91, 96, and 62%, respectively, at particle sizes of 75–250 μm. The highest COD removal of 70% was also achieved at particle sizes smaller than 75 μm. These findings indicate tha...

Three start-up techniques were investigated to evaluate the suitability of the bench-scale modified anaerobic inclining-baffled reactor (MAI-BR) for the treatment of recycled paper mill effluent (RPME) and to achieve an improved understanding of the inoculum to substrate ratio (ISR). The ISR ratios used were 3.53, 1.17, and 10.63 g volatile suspended solids (VSS)/g chemical oxygen demand (COD) for the first, second, and third start-ups, respectively. On a 30-d duration, the first start-up succeeded in removing 72% of the COD with an effluent pH of 6.2 and a methane production of 0.076 L/d. The second start-up was considered unfavorable after 16 d because of low methane production and effluent pH level. The third start-up with a 21-d duration was the best because of its 87% COD removal, 6.82 effluent pH, and 0.164 L/d methane production. The effluent volatile fatty acid (VFA)/alkalinity ratios were concurrently varied as 0.56, 0.45, and 0.034 for the first, second, and third start-ups, respectively...

The performance of modified anaerobic inclining-baffled reactor (MAI-BR) treating recycled paper mill effluent (RPME) was investigated by varying the influent chemical oxygen demand (CODin) concentration from 1000 to 4000 mg/L, and the hydraulic retention time (HRT) from 3 to 1 day, corresponding to an organic loading rate increase from 0.33 to 4 g COD/L day. Throughout 126 days of operation, a maximum removal efficiency of up to 96% of chemical oxygen demand (COD) and 99% of biological oxygen demand, methane (CH4) yield of 0.259 L CH4/g COD, and a stable effluent pH of 6.5 were achieved. Furthermore, the compartmental performance showed that most of the organic substrates were removed in the initial two compartments, resulting in low pH and alkalinity levels and a high concentration of volatile fatty acids. Overall, the results showed that the MAI-BR successfully treated RPME, and the performance was affected by the variation of HRT more than the CODin.

Sustainability of the environment has become a focus; hence the need for improvement and monitoring of textile waste water discharges, for which major concern is color. Color in textile dyeing and finishing effluents is as a result of large amounts of dye stuffs left during the dyeing stages and inefficient dyeing processes often resulting in unfixed forms. Waste water from Textile and dyeing industries contain many pollutants, making it high in organic and inorganic chemical content, total organic carbon (TOC), chemical oxygen demand (COD), and especially, strong color. It is thus difficult to be degraded by the conventional methods; hence the use of the advanced oxidation processes (AOPs). The advanced oxidative process is certainly not a very new treatment method as it has been studied and used extensively; however, hope remains for possible improvement, hence this review. AOPs are being researched more with a view to improve on the treatability of effluents and the hope to use the method for the complete mineralization of dyes. Although they are very effective in complete mineralization of pollutants, AOPs may be very expensive when used solely.

Leachate is a liquid produced from the biodegradation of solid waste in landfill and is normally referred as highly polluted wastewater. Various treatment methods are available and it is highly depended on the characteristics of the leachate. One of the common and simplest methods is using coagulation process. The application of pre-hydrolyzed coagulants in coagulation process is well known for water and wastewater treatment. However, information on the application of pre-hydrolyzed coagulants, especially pre-hydrolyzed iron (PHI), in partially stabilized leachate treatments is not well documented. This study examined the application of PHI on the partially stabilized leachate by determining the optimum basicity ratio, pH, and dose through the removals percentage of suspended solid (SS), color, and chemical oxygen demand (COD). Laboratory jar tests revealed that the optimum PHI basicity ratio, pH, and dosage were 0.1, 5, and 0.2 g/L Fe, respectively. The optimum removals of SS, color, and COD were...

Leachate is a major pollution source associated with municipal solid waste landfill. This study was carried out to evaluate the effectiveness of various techniques in treating mature landfill leachate generated from landfill in Malaysia, a tropical country. Treatment processes such as biological, ion exchange, coagulation–flocculation, adsorption, advanced oxidation processes (AOPs), and flotation were analyzed. The efficiency of each process was analyzed based on chemical oxygen demand (COD), color, and NH3-N percentage removals. Ion exchange treatment via cationic/anionic sequence achieved the best removal of color (96.8%), COD (87.9%), and NH3-N (93.8%) from leachate as compared with other treatment methods. Coagulation–flocculation and AOPs were successful for COD and color removals from leachate. However, both could not treat NH3-N effectively. Biological treatment could remove NH3-N (71%) effectively, but it was poor in terms of COD (29%) and color (22%) removals. Adsorption via a new carbon...

The characterization of landfill leachate has been well established. However, its biodegradation properties have not been well reported. Therefore, this research was undertaken to investigate the biodegradability of semi-aerobic sanitary landfill and the ratio of the biological oxygen demand (BOD) to chemical oxygen demand (COD) BOD5/COD, COD fraction on leachate from Pulau Burung landfill Site (PBLS). These parameters are important as they may provide appropriate and suitable treatment for this kind of leachate. In this research, leachate from two different ponds were studied i.e., the raw leachate from leachate collection pond and the leachate effluents of the treatment plant'. Five different measurement points were tested for each pond to understand the characterization for leachate. The soluble and particulate organic compound was separated by filtration using a 0.45μm pore size membrane filter. The results indicated that leachate in PBLS has low BOD5/COD ratio. The total COD (TCOD) ranged from 2040mg/L to 3160mg/L. The Biodegradable COD (BCOD), unbiodegradable COD (UBOD), soluble biodegradable (RBCOD), particlulate biodegradable (SBCOD), particulate inert (UPCOD), and soluble inert (USCOD) ranged from 53%-67%, 33%-47%, 38%-46%, 9%-25%, 12%-26%, and 18%-25%. This indicates, the leachate in Pulau Burung Landfill Site have different of COD fraction behavior compare with domestic wastewater. In which, leachate have low SBCOD, but relatively high in others COD fraction compare with domestic wastewater.

Treatment of recalcitrant landfill leachate was carried out using hydrogen peroxide (H2O2) and potassium permanganate (KMnO4). The treatment performance was reported in terms of colour, chemical oxygen demand (COD) and ammoniacal nitrogen (NH4-N). The effect of oxidant dosages and pH was determined and optimum conditions were determined considering the removal of parameters of interest. The optimum dosage of both oxidants was similar in terms of COD removal; however, H2O2 gave better removal (42 %) and similar results were obtained for NH4-N (24 %). KMnO4 proved better in terms of colour with a reduction of 74 % compared to 43 % by hydrogen peroxide at pH 7. Acidic conditions (pH 2–5) proved conducive towards the removal of all parameters with the exception of COD removal by KMnO4 that exhibited a low removal at pH 5 and increased with increasing pH. The COD reduction at pH 3 was ~38 % for KMnO4 and H2O2, whereas the reduction in NH4-N was 22 and 28 % for KMnO4 and H2O2, respectively. The COD and NH4-N removal performance of H2O2 was better compared with KMnO4; however, consistently higher colour removal was obtained for KMnO4.

One of an anaerobic stabilized landfill leachate in Malaysia underwent ozonation process. The sample rich in chemical oxygen demand (COD) was collected from Alor Pongsu Landfill Site, Perak (APLS). This site has been operating since year 2000. The leachate also contains other pollutants that exceeded the standard discharge limit for wastewater effluents. The effectiveness of ozone (O3) dosage, pH variation, and reaction time during ozonation was evaluated to measure the performance of O3 and determine the maximum operational conditions for this treatment. The maximum removal efficiency for COD was 50% at an ozone dosage of 31 g/m3, natural of pH 8.5, and reaction time of 60 min. The biodegradability ratio (BOD5/COD) improved from 0.08 to 0.23 after treatment with O3. The ozonation method has enhanced the biodegradability ratio and resulted high percentage removal of COD. This improvement showed that oxidation has a great potential to remediate recalcitrant pollutant wastes, such as landfill leachate.

Generally, the rainwater has low concentration of pollutants, whereby it is applicable for domestic water supply. Due to the low concentration of pollutants, further treatment such as adsorption is necessary to treat the harvested rainwater as an alternative source of drinking water supply. Therefore, this research has been carried out to determine the quality of rainwater from different types of locations, which are; rural residential area, urban residential area, agricultural area, industrial area, and open surface. The rainwater sampling was carried out from September 2014 to December 2015. The parameters that have been analysed during the sampling process are chemical oxygen demand (COD), turbidity, heavy metals, and Escherichia coli (E.coli). The sampling results show that the rainwater provides low concentration of contaminants. Thus, it has high potential to be used as alternative source of potable and non potable water supply with a suitable treatment. Due to that, an experimental work contained o...

Leachate production from landfilling contributes crucial pollutants to the environment. This study examined the potential of tin (IV) chloride as coagulant that involved charge neutralization and sweep flocculation mechanisms. The negative charge of leachate is neutralized by adding tin (IV) chloride as cationic coagulant which resulted precipitation and swept most of the colloids and dissolved solids that entrapped in the settling as hydrous oxide floc. Parameters such as suspended solid (SS) content, color, and chemical oxygen demand (COD) were analyzed using standard jar test procedures. The best condition was observed at pH 8, with removal efficiencies of 75.99 %, 99.29 % and 98.36 % for COD, SS, and color, respectively. At optimum dosage, tin (IV) chloride successfully removed 98.40 % for color, 99.54 % for SS and 71.53 % for COD. These results indicated the satisfactory performance of tin (IV) chloride. Hence, tin (IV) chloride is a potential coagulant for the treatment of Alor Pongsu Landfill leachate.

Anaerobically treated palm oil mill effluent (POME) used as an infant in the aerobic sequencing batch reactor (SBR). Three different treatments such as 15 g/L zeolite, municipal wastewater (MWW) and combining zeolite and municipal wastewater in comparing with the only aeration used in a lab scale batch study. Spectrophotometric analysis carried out for chemical oxygen demand (COD), ammonia nitrogen, total suspended solids, colour and total phosphorus as target characteristics of raw and treated POME. Zeolite and MWW augmented SBR contain POME + zeolite + MWW had significantly more performance compared with POME (blank) in all analyzed target factors. The results of this study indicate that MWW has significantly higher influence in decontamination of POME in comparing with zeolite. Combining zeolite and MWW in aerobic SBR could meet Malaysian environmental discharge for POME in 22 hours.

Leachate is a critical problem of sanitary landfills because it contains high organic matter and hazardous compounds that can generate negative environmental effects. The high chemical oxygen demand (COD) and color of the leachate necessitates its treatment before it can be released to the water body. Thus, an investigation into the performance of advanced oxidation processes (AOPs) was conducted using a combination of ozone (O3) with zirconium tetrachloride (ZrCl4) as catalyst in stabilized landfill leachate treatment. Such leachate was collected from the Alor Pongsu Landfill site (APLS), Perak, Malaysia. COD and color parameter were used as indicators to examine the effect of O3/ZrCl4 dosage, pH, and contact time. The experiment was run under gas flow rate of 1,000 mL/min±10% and temperature below 15 °C. The maximum removal obtained for COD and color were 88% and 100%, respectively. This outcome was achieved at 27 g/m3 ozone dosage, pH 6, 90 min reaction time, and dosage ratio of 1:2 (COD g: ZrCl4 g). T...

The purpose of this research is to analyse the biodegradability of leachate from Pulau Burung sanitary landfill (PBSL). PBSL is a semi-aerobic landfill which applies Fukuoka Method to reduce the amount of CH4 and enhance the stability of landfill compared to anaerobic types. This study compares two types of leachate, namely young and stabilized. In the present study, the fractions of biodegradable chemical oxygen demand (COD) which has significant value as a contaminant parameter was investigated. Aeration method was applied in examine the biodegradable COD fraction in both leachates while the BOD5/COD ratio was determined in order to analyse the quality of landfill. The results indicate that the stabilized leachate contains 15.15% of biodegradable COD while young leachate contains 25.16%, respectively. The BOD5/COD ratio for stabilized leachate shows 0.089 and categorized as ‘matured’ or ‘stable’ landfill while the BOD5/COD ratio for young leachate shows higher value (0.103) which verified the landfill a...

This study investigated the effects of O3 and O3/H2O2/Fe 2þ in the advanced oxidation processes (AOPs) on the biodegradable and soluble characteristics of semi-aerobic stabilized solid waste leachate. The biodegradability (BOD5/chemical oxygen demand, COD) ratio improved from 0.034 to 0.05 and 0.1 following O3 and O3/H2O2/Fe 2þ , respectively. Fractions of biodegradable COD(bi) (24%), non-biodegradable COD(ubi) (76%), soluble COD(s) (59%), biodegradable soluble COD(bsi) (38%), non-biodegradable soluble COD(ubsi) (62%), and particulate COD (PCOD) (41%) in stabilized leachate were also investigated. The fraction of COD(bi) increased to 28 and 36% after applying O3 and O3/AOPs, respectively. COD(S) increased to 59% after O3 and to 72% after O3/AOPs, whereas COD(bsi) increased to 38 and 51% after O3 and O3/AOPs, respectively. The removal efficiency of COD(S) was obtained at 5% after O3 alone and improved to 51% following ozone-based AOPs, whereas the removal efficiency of PCOD improved from 25% after O3 to 71% after ozone-based AOPs.

Ozonation, combined with the Fenton process (O(3)/H(2)O(2)/Fe(2+)), was used to treat matured landfill leachate. The effectiveness of the Fenton molar ratio, Fenton concentration, pH variance, and reaction time were evaluated under optimum operational conditions. The optimum removal values of chemical oxygen demand (COD), color, and NH(3)-N were found to be 65%, 98%, and 12%, respectively, for 90 min of ozonation using a Fenton molar ratio of 1 at a Fenton concentration of 0.05 mol L(-1) (1700 mg/L) H(2)O(2) and 0.05 mol L(-1) (2800 mg/L) Fe(2+) at pH 7. The maximum removal of NH(3)-N was 19% at 150 min. The ozone consumption for COD removal was 0.63 kg O(3)/kg COD. To evaluate the effectiveness, the results obtained in the treatment of stabilized leachate were compared with those obtained from other treatment processes, such as ozone alone, Fenton reaction alone, as well as combined Fenton and ozone. The combined method (i.e., O(3)/H(2)O(2)/Fe(2+)) achieved higher removal efficiencies for COD, color, and NH(3)-N compared with other studied applications.

Inorganic and organic pollutants continue to pose major problems in receiving water bodies. To overcome such problems, a new composite adsorbent material combining excellent properties of activated carbon, zeolite, and low cost adsorbents, that is, limestone and rice husk ash, was fabricated. The study also determined the capability of the new composite media to remove contaminants from semiaerobic stabilized landfill leachate. The process of identifying the optimum composition of the new adsorbent was carried out using batch technique. Further, isotherm study and regeneration of the media were investigated. Results indicated that there was favorable adsorption by both Langmuir and Freundlich isotherms. However, Langmuir isotherms were slightly better fitted for ammonia, chemical oxygen demand (COD), and color removal in terms of regression coefficients (R2). According to the Langmuir model, adsorption capacity of ammonia, COD, color, and iron reached 37.59 mg/g, 22.99 mg/g, 43.67 Pt-Co/g, and 0....

Stabilized leachate generated from an aged sanitary landfill is typically classified as nonbiodegradable. The ion exchange technique has been rarely used for the treatment of stabilized landfill leachate, particularly for the removal of color and nonbiodegradable substances (measured as chemical oxygen demand [COD]). Thus, this study was undertaken to examine the effectiveness of anion-exchange resin (i.e., INDION FFIP MB) in removing color and COD from stabilized semi-aerobic landfill leachate in Malaysia. To predict the performance of the process, the effects of anion exchanger dosage, shaking speed, contact time, and pH on pollutant removal efficiency were investigated. Adsorption of color and COD was realistically explained through Langmuir and Freundlich isotherms. Adsorption kinetics mechanism was studied using reaction-based models. The anionic resin efficiently removed 91.2% color and 69.4% COD at pH 3 and removed only 69.4% color and 60.3% COD at pH 9. The color and COD adsorption data w...

In this research, two types of sequencing batch reactors (SBRs) with 8 h of cycle times, namely non-powdered activated carbon (NPAC-SBR) and powdered activated carbon (PAC-SBR), were used for the treatment of raw leachates at Kulim and Pulau Burung landfill sites. To test the performance of SBRs, phenols, total iron, zinc, ammonia, nitrite, nitrate, color, suspended solids, chemical oxygen demand, biochemical oxygen demand, and total dissolved salts removal efficiencies and sludge volume index (SVI) were studied at both sites. The rates of phenols removal, for instance in NPAC-SBRs and PAC-SBRs at Kulim, were 25% and 55%, respectively, whereas those at Pulau Buring were 94.81% and 97.75%, respectively. PAC as adsorbent in PAC-SBRs enhanced the removal efficiencies of the aforementioned pollutants from leachates at both sites. In addition, PAC as adsorbent decreased the SVI values at Kulim (59.7 mL/g) and Pulau Burung (91.4 mL/g) leachates and improved the nitrification and denitrification processes.

The sequencing batch reactor (SBR) process was used for the treatment of raw landfill leachate. Optimum preliminary parameters of leachate/activated sludge ratio, powdered activated carbon (PAC) dosage, and settling time were studied. Optimum obtained parameters (mixing ratio of 10%, PAC dosage of 10 g/L, and settling time of 1.5 h) were applied on two types of SBRs, namely, non-powdered and powdered activated carbon (NPAC and PAC, respectively). Consequently, the effect of factors, the aeration rate and contact time, on both NPAC and PAC reactors were studied. Response surface methodology was used for the design, analysis, and optimization of the experiments. Removal efficiencies of ammonia (NH3-N), color, chemical oxygen demand (COD), total dissolved salts (TDS), and sludge volume index (SVI) were measured for 13 experiments. Based on the obtained results, the optimum aeration rate and contact time for both NPAC and PAC reactors were 2 and 1 L/min and 5.56 and 5.5 h, respectively. Better performance (in...

This study evaluated the performance of swim-bed reactors combined with a novel acrylic fiber carrier biofringe conventional activated sludge (AS + BF) and the only conventional activated sludge (AS) reactors for the treatment of semi-aerobic landfill leachate. Partially stabilized leachate was characterized and termed as resistant to biodegradation due to high concentration of refractory compounds. Experiments were conducted using two 10 L laboratory-scale swim-bed reactors in parallel at room temperature (25 °C) and pH 7.0 ± 0.5. The removal performance of AS + BF and AS alone in treating leachate was compared in terms of chemical oxygen demand (COD), biological oxygen demand (BOD 5 ), total kjehldahl nitrogen (TKN), ammonia nitrogen (NH 4 –N), nitrite, nitrate, PO 4 3− , colour and suspended solids (SS). Sludge reduction was achieved in AS + BF reactor. Swim bed BF efficiently removed nitrite, nitrate and phosphorus from leachate; however, the removal performance was not significant for COD and ammonia nitrogen.

FeCl 3 coagulation and dissolved air flotation (DAF) were combined to assess the success of these techniques for the treatment of semiaerobic landfill leachate. Treatment parameters (i.e.; flow rate, coagulant dosage, pH and injection time) were optimized via response surface methodology (RSM) using central composite design (CCD) to yield the maximum removal of turbidity, chemical oxygen demand (COD), color and ammonia nitrogen (NH 3 -N). Model-determined optimum conditions were tested to confirm the predicted results. Initial concentrations of turbidity (259 FAU), COD (2010 mg/L), color (4000 PtCo) and NH 3 -N (1975 mg/L) were reduced by 50%, 75%, 93% and 41%, respectively. These experimental results were consistent with those predicted by the model. The optimum operating conditions for coagulation and DAF were 599.22 mg/L of FeCl 3 at pH 4.76 followed with saturator pressure of 600 kPa, flow rate 6 L/min and injection time of 101 s.

Three types of sequencing batch reactors (SBRs) were used in the treatment of landfill leachate in Kulim, Malaysia. These SBRs were a non-powdered activated carbon SBR (NPAC-SBR), powdered activated carbon SBR (PAC-SBR), and double react-settle SBR (DRS-SBR). Powdered activated carbon was used to augment the SBR process in the PAC and DRS reactors. The first two reactors operate on five conventional phases (i.e., fill, react, settle, draw, and idle), whereas the third operates on seven phases (i.e., fill, react I, settle I, react II, settle II, draw, and idle). Raw landfill leachate was treated in 20 experiments. The PAC- and DRS-SBRs exhibited better performance, improved sludge characteristics, and superior aeration energy savings compared with the NPAC-SBR. Results for mean sludge volume index, total dry solids in sludge, saved aeration energy, removed ammonia, chemical oxygen demand, color, and total dissolved salts were 334.4 mL/g, 1.06%, 0%, 89.4%, − 42.9, 10.2%, and 35.9% , respectively, for the NPAC-SBR, and 27.5 mL/g, 2.01%, 64.03%, 85.5%, 50.4, 45%, and 38.3%, respectively, for the DRS-SBR. The PAC-augmented DRS-SBR exhibited a significant improvement in the treatment of landfill leachate compared with the NPAC-SBR.

This study analyzes and compares the results of leachate composition at the semi-aerobic Pulau Burung Landfill Site (PBLS) (unaerated pond and intermittently aerated pond) and the anaerobic Kulim Sanitary Landfill in the northern region of Malaysia. The raw samples were collected and analyzed for twenty parameters. The average values of the parameters such as phenols (1.2, 6.7, and 2.6 mg/L), total nitrogen (448, 1200, and 300 mg/L N-TN), ammonia-N (542, 1568, and 538 mg/L NH3-N), nitrite (91, 49, and 52 mg/L NO2−-N), total phosphorus (21, 17, and 19 mg/L), BOD5 (83, 243, and 326 mg/L), COD (935, 2345, and 1892 mg/L), BOD5/COD (0.096,0.1124,0.205%), pH (8.20, 8.28, and 7.76), turbidity (1546, 180, and 1936 Formazin attenuation units (FAU)), and color (3334, 3347, and 4041 Pt Co) for leachate at the semi-aerobic PBLS (unaerated and intermittently aerated) and the anaerobic Kulim Sanitary Landfill were recorded, respectively. The obtained results were compared with previously published data and data from the Malaysia Environmental Quality Act 1974. The results indicated that Pulau Burung leachate was more stabilized compared with Kulim leachate. Furthermore, the aeration process in PBLS has a considerable effect on reducing the concentration of several pollutants. The studied leachate requires treatment to minimize the pollutants to an acceptable level prior to discharge into water courses.

Chemical oxygen demand (COD) and ammoniacal nitrogen have always been the crucially problematic parameters in landfill leachate treatment. This study was conducted to investigate the adsorption properties of ammoniacal nitrogen and COD in semi-aerobic leachate from the Pulau Burung landfill site on zeolite, activated carbon and a new composite media in terms of adsorption isotherm and kinetic. The results show that all adsorbents fitted well with both Langmuir and Freundlich isotherms (R2 > 0.9) for ammonia adsorption. A comparison study indicated that the adsorption capacity of composite adsorbent towards ammoniacal nitrogen was higher than zeolite and activated carbon and comparable to activated carbon for COD. Findings from a kinetic study indicated that the adsorption of ammonia on new composite adsorbent and zeolite follow almost all kinetic models such as pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion model, although pseudo-second-order was the most dominant. COD adsorption fitted well with the pseudo-second-order kinetic model, while activated carbon obeys the pseudo-first-order and intra-particle models.

Advanced oxidation processes (AOPs) such as Fenton, electro-Fenton and photo-Fenton have been applied effectively to remove refractory organics from landfill leachate. The Fenton reaction is based on the addition of hydrogen peroxide to the wastewater or leachate in the presence of ferrous salt as a catalyst. The use of this technique has proved to be one of the best compromises for landfill leachate treatment because of its environmental and economical advantages. Fenton process has been used successfully to mineralize wide range of organic constituents present in landfill leachate particularly those recalcitrant to biological degradation. The present study reviews the use of Fenton and related processes in terms of their increased application to landfill leachate. The effects of various operating parameters and their optimum ranges for maximum COD and color removal are reviewed with the conclusion that the Fenton and related processes are effective and competitive with other technologies for degradation of both raw and pre-treated landfill leachate.

The treatability of stabilized sanitary landfill leachate via synthetic anion exchange resin (INDION FFIP MB) was investigated. An ideal experimental design was conducted based on central composite design using a response surface methodology to assess individual and interactive effects of critical operational variables (i.e., anionic dosage; contact time; shaking speed) and pH on treatment performance in terms of color, chemical oxygen demand (COD), suspended solid (SS), and turbidity removal efficiencies. Optimum operational conditions were established as 30.9 cm 3 anionic dosage, 90 min contact time, 150 rpm shaking speed, and pH 3.1. Under these conditions, the color, COD, SS, and turbidity removal efficiencies of 91.5, 70.3, 93.1, and 92.4% were experimentally attained and were found to fit well with the prediction model. According to these results, stabilized leachate treatment using INDION FFIP MB could be an effective alternative in the administration of color, COD, SS, and turbidity problems of landfill leachates.

Coagulation–flocculation as a relatively simple physical–chemical technique was applied in this work. Polymeric forms of metal coagulants which are increasingly applied in water treatment are not well documented in leachate treatment. This study examined poly-aluminum chloride (PAC) and aluminum sulfate (alum) in treating a partially stabilized leachate, and compared attained results in respect to the removal of chemical oxygen demand (COD), turbidity, color and total suspended solid (TSS). Series of coagulation–flocculation tests were carried out to optimize the coagulant dose, pH, and operating conditions (speed and time for rapid and slow mixing). Optimum coagulant dose (OpCD) and pH were respectively found at 1.9 g/L and 7.5 for PAC, and 9.4 g/L and 7 for alum. A concurrent optimization of speed and time of mixing resulted in a considerable enhancement in COD removal: 84.50% and 56.76% for alum and PAC, respectively. Using PAC, almost complete removals for physical parameters of leachate (turbidity: 99.18%, color: 97.26%, and TSS: 99.22%) were achieved; whereas alum showed inferior removal (turbidity 94.82%, color 92.23%, and TSS 95.92%). However, results revealed PAC is not as efficient as alum for COD elimination, where the alum dose (9.4 g/L) was about fivefold that of PAC (1.9 g/L).