Semi-aerobic Landfill Leachate Research Articles

The Potential Use of Nephelium lappaceum Seed as Coagulant-Coagulant Aid in the Treatment of Semi-Aerobic Landfill Leachate.

Chemical-based coagulants and flocculants are commonly used in the coagulation–flocculation process. However, the drawbacks of using these chemical materials have triggered researchers to find natural materials to substitute or reduce the number of chemical-based coagulants and flocculants. This study examines the potential application of Nephelium lappaceum seeds as a natural coagulant–coagulant aid with Tin (IV) chloride (SnCl4) in eliminating suspended solids (SS), colour, and chemical oxygen demand (COD) from landfill leachate. Results showed that the efficiency of Nephelium lappaceum was low when used as the main coagulant in the standard jar test. When SnCl4 was applied as a single coagulant, as much as 98.4% of SS, 96.8% of colour and 82.0% of COD was eliminated at an optimal dose of 10.5 g/L and pH 7. The higher removal efficiency of colour (88.8%) was obtained when 8.40 g/L of SnCl4 was applied with a support of 3 g/L of Nephelium lappaceum. When SnCl4 was utilised as a coagulant, and Nephelium lappaceum seed was used as a flocculant, the removal of pollutants generally improved. Overall, this research showed that Nephelium lappaceum seed is a viable natural alternative for treating landfill leachate as a coagulant aid.

Degradation of refractory organic matter in the effluent from a semi-aerobic aged refuse biofilter-treated landfill leachate by a nano-Fe3O4 enhanced ozonation process.

In this study, the transformation and degradation mechanisms of refractory organic matter in biologically treated leachate from a semi-aerobic aged refuse biofilter (SAARB) in a nano-Fe3O4 enhanced ozonation process (nFe3O4-O3) were investigated in batch experiments. A continuous experiment then confirmed the effectiveness of the process for SAARB effluent treatment. In a batch experiment, the effects of influencing factors, including nFe3O4 dosage, O3 dosage and initial pH on the treatment performance of nFe3O4-O3 process, were comprehensively investigated. The results showed that when the nFe3O4 dosage = 6 g L-1, O3 dosage = 0.15 L minute-1 and initial pH = 7, the total organic carbon, absorbance at 254 nm and colour number removal efficiencies were 40.58%, 62.55% and 89.80%, respectively. In addition, most of the humic- and fulvic-like substances in the SAARB effluent were removed, and the condensation degree, aromaticity and humification degree of the organics were substantially reduced. The morphology and elemental valence state analysis showed that the nFe3O4 in the process was relatively stable and could form an nFe3O4-organic complex. Therefore, the probability of organics reacting with hydroxyl radical increased and the oxidation efficiency was enhanced. In the continuous experiment, both the O3 dosage and hydraulic retention time (HRT) were the key influencing factors. The treatment efficiency of the nFe3O4-O3 process was enhanced at a higher O3 dosage and longer HRT. The electrical energy consumption of the continuous nFe3O3-O3 process was calculated to be 17.72 kW h m-3 in SAARB effluent treatment. This study proved the feasibility of biologically treated landfill leachate treatment by the nFe3O3-O3 process.

Potential use of oil palm trunk starch as coagulant and coagulant aid in semi-aerobic landfill leachate treatment

Abstract Landfill leachate is highly polluted wastewater and generated as a result of water infiltration through solid waste produced domestically and industrially. This study investigates the potential use of oil palm trunk starch (OPTS) and crosslinks oil palm trunk starch (C-OPTS) as coagulant and coagulant aid in tandem with polyaluminum chloride (PAC) for the treatment of landfill leachate. As primary coagulant, the optimum pH and dosage for OPTC were 7 and 500 mg/L, respectively. For C-OPTS, the optimum conditions were pH 8.3 and 1,000 mg/L C-OPTS dosage. However, the optimum conditions for PAC were pH 7 and 8,000 mg/L PAC dosage. Results show that OPTS demonstrated superior feasibility as a selective coagulant targeting heavy metals such as Mn (100% removal), Cu (95.6% removal), Zn (100% removal), and PO43− (100% removal), whereas C-OPTS can be employed as both bulk and selective coagulants. On the other hand, C-OPTS prevailed over PAC in Mn, Zn, PO43−, and chemical oxygen demand (COD) removals by huge margins of 100%, 54.8%, 24.3%, and 17.1%, respectively, without any pH adjustments and with optimum dosage 87.5% lower than that of PAC.

The application of crosslinking oil palm trunk starch coagulants for landfill leachate treatment

Coagulation-flocculation has been extensively used as a semi-aerobic landfill leachate treatment, prior to other treatment methods. Polyaluminium chloride (PAC) coagulants is prominent in landfill leachate treatment, however the application of PAC may introduce potentially harmful residuals into the aquatic environment. In this study, crosslinked starch-based coagulants had been produced from oil palm trunk waste (C-OPTS). To date, no attempt has been made to avail crosslinked oil palm trunk starch application in landfill leachate treatment. Based on the results, C-OPTS can be employed as coagulants. Jar test results had ascertained that optimum pH and dosages value for C-OPTS and PAC. Indeed, no pH adjustment was required for C-OPTS and its optimum dosage was only one-eighth of PAC optimum dosage. Therefore, C-OPTS would be an alternative coagulant substituting PAC, depending on leachate condition. The overall findings concluded that C-OPTS were feasible for landfill leachate treatment in terms of coagulation performance and sustainable environmental management.

The application of crosslinking oil palm trunk starch coagulants for landfill leachate treatment

Coagulation-flocculation has been extensively used as a semi-aerobic landfill leachate treatment, prior to other treatment methods. Polyaluminium chloride (PAC) coagulants is prominent in landfill leachate treatment, however the application of PAC may introduce potentially harmful residuals into the aquatic environment. In this study, crosslinked starch-based coagulants had been produced from oil palm trunk waste (C-OPTS). To date, no attempt has been made to avail crosslinked oil palm trunk starch application in landfill leachate treatment. Based on the results, C-OPTS can be employed as coagulants. Jar test results had ascertained that optimum pH and dosages value for C-OPTS and PAC. Indeed, no pH adjustment was required for C-OPTS and its optimum dosage was only one-eighth of PAC optimum dosage. Therefore, C-OPTS would be an alternative coagulant substituting PAC, depending on leachate condition. The overall findings concluded that C-OPTS were feasible for landfill leachate treatment in terms of coagulation performance and sustainable environmental management.

Effect of Modified Micro-Sand, Poly-Aluminium Chloride and Cationic Polymer on Coagulation-Flocculation Process of Landfill Leachate

Sanitary landfill leachate is considered as highly polluted wastewater, if without any treatment and discharge into water system will affect water quality. This study was carried out to assess the treatability of the semi-aerobic landfill leachate via coagulation-flocculation using poly-aluminum chloride (PAC), cationic polymer and modified micro sand. Leachate was collected from Pulau Burung Sanitary Landfill located in Penang, Malaysia. Coagulation-flocculation was performed by using jar test equipment and the effect of pH, dose of coagulant and polymer toward removal of chemical oxygen demand (COD), color and suspended solid (SS) were examined. Micro sand also had been used in this study to compare settling time between coagulation-flocculation process with and without the aid of micro sand. The optimum pH, dose of coagulant (PAC) and dose of polymer (cationic) were achieved at 7.0, 1,000 mg/L and 8 mg/L, respectively. The dose of micro sand used for the settling time process is 300 mg/L. Results showed 52.66 % removal of COD, 97.16% removal of SS and 96.44% removal of color were obtained under optimum condition. The durations of settling time to settle down the sludge or particle that formed during coagulation-flocculation process were recorded at 1 minute (modified sand), 20 minutes (raw micro sand) and 45 minutes (without micro sand).

Potential use of zirconium (IV) chloride as coagulant to treat semi-aerobic leachate treatment

Coagulation-flocculation is the most common chemical treatment method for wastewater treatment. Coagulant acts as neutralising agents for the electrical charges of particles in leachate. ZrCl4, which has never been applied for leachate treatment before, was tested in this research. Standard jar testing was conducted to determine the optimal pH and dosage in removing colour, suspended solids (SSs), ammonia, and organic content [ultraviolet absorbance at 254 nm wavelengths (UV254)] from semi-aerobic landfill leachate. The optimal ZrCl4 dosage and pH were 1,500 mg/L and 4, respectively. These values corresponded to 93.4%, 94.3%, and 97% removals for SS, colour, and UV254, respectively. However, ammonia could not be removed by the coagulant, with only 2.2% of removal at pH 4 and 1,500 mg/L ZrCl4 dosage.

Extraction and application of starch-based coagulants from sago trunk for semi-aerobic landfill leachate treatment.

Malaysia is one of the highest starch producers. In this study, sago starch was utilized as a natural coagulant aid to reduce the dosage of aluminum-based coagulant in leachate treatment. The potential of native sago trunk starch (NSTS) and commercial sago starch (CSS) was evaluated as sole coagulant and coagulant aid in the presence of polyaluminum chloride (PACl) in the removal of color, suspended solids (SS), NH3-N, turbidity, chemical oxygen demand, organic UV254, Cd, and Ni. Leachate was sampled from Pulau Burung Landfill Site, one of the semi-aerobic landfills in Malaysia. The optimum dosage for PACl in the presence of NSTS or CSS as coagulant aid was reduced from 3100 to 2000 mg/L. In the presence of 2000 mg/L PACl with 6000 mg/L NSTS and 2000 mg/L PACl with 5000 mg/L CSS, the removal performance for color, SS, and turbidity are 94.7, 99.2, and 98.9%, respectively. Similar results were obtained with the use of 3100 mg/L PACl alone. Therefore, CSS and NSTS can be used as coagulant aid.

The dependence of the methylation of mercury on the landfill stabilization process and implications for the landfill management

Mercury species and other chemical characteristics of the leachate from anaerobic and semi-aerobic landfills were analyzed to investigate the factors that control mercury methylation during the landfill stabilization process. At the early landfill stage, the total mercury (THg) and the monomethyl mercury (MMHg) released rapidly and significantly, the THg concentration of the semi-aerobic landfill leachate was obviously higher than that of the anaerobic landfill leachate, while compared with the semi-aerobic landfill, the MMHg concentration in the anaerobic landfill was higher. As the landfill time increased, both of THg and MMHg concentration decreased quickly, the THg concentration in the anaerobic landfill was much higher than that in semi-aerobic landfill, while the MMHg concentration in the anaerobic landfill was lower than that in the semi-aerobic landfill. Generally, the concentrations of dimethyl mercury (DMHg) in the anaerobic landfill leachate were slightly higher than in the semi-aerobic landfill leachate during the stabilization process. A significant positive correlation was found between the DMHg concentrations and the pH value in anaerobic landfill leachate, but this correlation was opposite in the semi-aerobic landfill. The oxidative–reductive potential (ORP) condition was found to be the controlling factor of the methylation process during the early stage. However, the chemical characteristics, especially the TOC concentration, appeared to be the dominant factor affecting the methylation process as the landfill time increased.

Application of response surface methodology (RSM) for optimization of semi-aerobic landfill leachate treatment using ozone

The removal efficiencies for chemical oxygen demand (COD), ammoniacal nitrogen (NH3–N), and color, as well as ozone consumption (OC) from the Malaysian semi-aerobic landfill stabilized leachate using ozone reactor, were investigated. Central composite design with response surface methodology was applied to evaluate the interaction and relationship between operating variables (i.e., ozone dosage, COD concentration, and reaction time) and to develop the optimum operating condition. Based on statistical analysis, Quadratic models for the four responses (COD, NH3–N, color, and OC) proved to be significant with very low probability values (<0.0001). The obtained optimum conditions were 70 g/m3 ozone, 250 mg/l COD, and 60 min reaction time. The results obtained by the predicted model were 26.7, 7.1, and 92 % removal for COD, NH3–N, and color, respectively, with 9.42 (kgO3/kg COD) OC. The predicted results fitted well with the results of the laboratory experiment.

Initial Characterization of Semi-aerobic Landfill Leachate Based On Its Biodegradation

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.

Potential of KMnO4 and H2O2 in treating semi-aerobic landfill leachate

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.

The effect of aerobic conditions on the complexation ability between mercury and humic acid from landfill leachate and its implication for the environment

Three-dimensional excitation emission matrix (3DEEM) fluorescence spectroscopy was employed to investigate the structure and characteristics of humic acid (HA) from landfills at different stabilization processes. The results show that the HA in anaerobic landfill leachate stabilized more rapidly than that in semi-aerobic landfill leachate. There were strong interactions between HA and Hg, the S content as well as the oxygen-containing ligands of the HA played a key role in the complexation with mercury. The higher complexation capacity (CL) and stability constant (logK) of HA from anaerobic landfill leachate implies that it is important to strengthen the control of mercury transportation in anaerobic landfills during the early stabilization process. The logK and CL of HA from semi-aerobic landfill leachate increased with the landfill time indicate that control of leachate Hg contamination in the latter stage is of great significance in semi-aerobic landfills.

Preparation of banana frond activated carbon by microwave induced activation for the removal of boron and total iron from landfill leachate

The present work demonstrates the preparation of banana frond derived activated carbon (BFAC) by microwave induced KOH activation for the adsorptive removal of boron and total iron from the semi-aerobic landfill leachate. The physical and chemical properties of BFAC were evaluated by pore structural analysis, scanning electron microscopy and Fourier transform infrared spectroscopy. The effects of adsorbent dosage, contact time, solution pH and temperature on the adsorption performance were examined in a batch mode study. The experimental results manifested that the adsorptive removal of boron and total iron increased with increasing the adsorbent dosage, contact time and temperature, accomplished the adsorptive removal of boron and total iron of 93.56% and 95.14%, respectively. Equilibrium data was best confronted to the pseudo-second-order kinetic model, while the adsorptive removal of boron and total iron onto BFAC was satisfactory described by the Freundlich and Langmuir isotherm models. The findings illustrated the applicability of BFAC as an ideal on-site solution for the adsorptive treatment of boron and total iron from the contaminated landfill leachate.

Batch adsorption of semi-aerobic landfill leachate by granular activated carbon prepared by microwave heating

In this work, tamarind fruit seed derived granular activated carbon (TSAC) was prepared by microwave heating for the adsorptive treatment of semi-aerobic landfill leachate. TSAC was examined by pore structural analysis and determination of surface acidity/basicity. The effects of adsorbent dosage, contact time, and solution pH on the adsorptive removal of color and non-biodegradable constituents, expressed in term of chemical oxygen demand (COD) were quantified. The experimental results manifested that the adsorptive removal of color and COD increased with increasing the adsorbent dosage and contact time, with the adsorptive removal of color and COD of 91.23% and 79.93%, respectively, at the adsorbent dosage of 6mg/200mL and pH 6. The adsorption kinetic was satisfactory fitted to the pseudo-second-order kinetic model. Equilibrium data were favorably described by the Langmuir isotherm model, showing a monolayer adsorption capacity for color and COD of 168.57Pt–Co/g and 64.93mg/g at 30°C, respectively.

Preparation of tamarind fruit seed activated carbon by microwave heating for the adsorptive treatment of landfill leachate: A laboratory column evaluation

The preparation of tamarind fruit seed granular activated carbon (TSAC) by microwave induced chemical activation for the adsorptive treatment of semi-aerobic landfill leachate has been attempted. The chemical and physical properties of TSAC were examined. A series of column tests were performed to determine the breakthrough characteristics, by varying the operational parameters, hydraulic loading rate (5–20mL/min) and adsorbent bed height (15–21cm). Ammonical nitrogen and chemical oxygen demand (COD), which provide a prerequisite insight into the prediction of leachate quality was quantified. Results illustrated an encouraging performance for the adsorptive removal of ammonical nitrogen and COD, with the highest bed capacity of 84.69 and 55.09mg/g respectively, at the hydraulic loading rate of 5mL/min and adsorbent bed height of 21cm. The dynamic adsorption behavior was satisfactory described by the Thomas and Yoon–Nelson models. The findings demonstrated the applicability of TSAC for the adsorptive treatment of landfill leachate.

Preparation of activated carbon from sugarcane bagasse by microwave assisted activation for the remediation of semi-aerobic landfill leachate

This study evaluates the sugarcane bagasse derived activated carbon (SBAC) prepared by microwave heating for the adsorptive removal of ammonical nitrogen and orthophosphate from the semi-aerobic landfill leachate. The physical and chemical properties of SBAC were examined by pore structural analysis, scanning electron microscopy, Fourier transform infrared spectroscopy and elemental analysis. The effects of adsorbent dosage, contact time and solution pH on the adsorption performance were investigated in a batch mode study at 30°C. Equilibrium data were favorably described by the Langmuir isotherm model, with a maximum monolayer adsorption capacity for ammonical nitrogen and orthophosphate of 138.46 and 12.81mg/g, respectively, while the adsorption kinetic was best fitted to the pseudo-second-order kinetic model. The results illustrated the potential of sugarcane bagasse derived activated carbon for the adsorptive treatment of semi-aerobic landfill leachate.

Color and Chemical Oxygen Demand Removal from Mature Semi-Aerobic Landfill Leachate Using Anion-Exchange Resin: An Equilibrium and Kinetic Study

Abstract 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...

The Simulation Study on the Rules of Spatial and Temporal Changes of Total Nitrogen in Semi-Aerobic Landfill Leachate in the Laboratory

Two experimental equipments of semi-aerobic landfill and anaerobic landfill were constructed. The total nitrogen concentrations of leachate (Recorded as CTN) that located at the bottom of equipments were determined periodically (1 or 2 times per week), the variation laws of CTN that located at the bottom of two landfill equipments with time were researched, and the reasons for the differences were also analyzed; During the period that the degradation of the landfill waste came into a relatively stable stage, the leachate that located at each sampling points of upper, middle and lower horizontal sections of the landfill equipments was collected periodically, and the CTN was determined, the CTN data of each point of upper, middle and lower layers were processed by using Surfer software respectively, and the spacial variation characteristics and differences of two landfill equipments were also discussed. The results indicated that the CTN of each point of the semi-aerobic landfill treatment were significantly lower than the corresponding anaerobic landfill treatment, the semi-aerobic landfill treatment could achieve the effective removal of total nitrogen from the leachate, and could accelerate the process of degradation stabilization and balance of total nitrogen in leachate.

Bacterial community composition and abundance in leachate of semi-aerobic and anaerobic landfills

The abundance and phylogenetic composition of bacterial community in leachate of semi-aerobic and anaerobic landfill were compared through real-time polymerase chain reaction and denaturing gradient gel electrophoresis. In semi-aerobic landfill scenario, the bacterial 16S rRNA copy numbers in leachate had no significant reduction from initial stage to stable period. In the scenario of anaerobic landfill, the largest bacterial 16S rRNA gene copy number was found in leachate at initial stage, but it reduced significantly at stable period. Moreover, methane-oxidizing bacteria population in stable period was lower than that in initial period in both two landfill processes. However, semi-aerobic landfill leachate had more methanotrophic bacteria populations than that in the anaerobic one. Furthermore, according to the sequences and phylogenetic analysis, obvious difference could be detected in bacterial community composition in different scenarios. Proteobacteria and bacteroidetes took up a dominantly higher proportion in semi-aerobic landfill leachate. To summarize up, different landfill methods and its landfill ages had crucial impacts on bacterial abundance and composition in leachate of semi-aerobic and anaerobic landfills.