Coagulation of landfill leachate by FeCl 3 : process optimization using Box–Behnken design (RSM (original) (raw)
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DESALINATION AND WATER TREATMENT
The aim of this study is to assess the performance of an industrial effluent steel industrial wastewater (SIWW) highly loaded with ferric salts from Maghreb Steel Company as coagulant for stabilized landfill leachate treatment. Response surface methodology and central composite design were applied to optimize the coagulation-flocculation process and to model the relationships between independent variables (coagulant dose and effluent pH) and responses (chemical oxygen demand (COD) and turbidity removal, and sludge production). Quadratic polynomial models developed for these responses indicated that the optimum conditions were 8 mL/L of SIWW at pH 2.75. These results showed good agreement between experimental and model predictions. 55.43% and 87.55% of COD and turbidity removal, respectively and with 19 mL/L of sludge production from treatment of this leachate by coagulation-flocculation using a SIWW-based coagulant were demonstrated. Accordingly, it is concluded that SIWW can be used as an effective and alternative coagulant for the pre-treatment of stabilized landfill leachate by a coagulation-flocculation process.
Journal of Sustainable Development, 2009
The effect of a coagulation process with ferrous sulfate as a coagulant on COD, apparent color and turbidity was evaluated using response surface methodology (RSM). A jar test method was used for the pre-treatment of mature landfill leachate of the Pulau Burung Sanitary Landfill, Malaysia. The results of response surface methodology (RSM) showed that ferrous sulfate was most efficient under alkaline conditions and with a coagulant dosage 10 g/l. At the optimum setting for coagulant dosage was 10 g/l and pH 11.7, resulted in maximum of (22%) in COD, (42%) in apparent color, and (31%) in turbidity. It was observed that the COD, apparent color and turbidity reductions decreased with pH and FeSO 4 levels beyond the optimum conditions. This paper illustrates the usefulness of experimental design in running experiments and optimization.
2015
Coagulation–flocculation is a relatively simple physical–chemical technique in treatment of old and stabilized leachate which has been practiced using a variety of conventional coagulants. Polymeric forms of metal coagulants which are increasingly applied in water treatment are not well documented in landfill leachate treatment. In this research, capability of poly-aluminum chloride (PACl ) in the treatment of stabilized leachate from Qazvin Landfill Site, Iran was studied. The removal efficiencies for chemical oxygen demand (COD), turbidity, color and total suspended solid (TSS) obtained using PACl were compared with those obtained using alum as a conventional coagulant. Central composite design (CCD) and response surface method (RSM) were applied to optimize the operating variables including coagulant dosage and pH. Quadratic models were developed for the four responses (COD, turbidity, color and TSS). The results of this study indicated that the optimum conditions were PACl dosag...
Avicenna Journal of Environmental Health Engineering, 2019
Landfill leachate is highly polluted and generated as a result of water infiltration through solid waste produced domestically and industrially. This study investigated the applicability of the response surface methodology (RSM) to optimize the removal performances of chemical oxygen demand (COD), color, and suspended solids (SS) from landfill leachate by coagulation process using Tin tetrachloride pentahydrate. The leachate samples were collected from Alor Pongsu Landfill (APLS) in Perak, Malaysia. Before starting the experiments, general characterization was carried out for raw leachate samples to investigate their physical and chemical properties. The effects of the dosage and pH of SnCl 4 on the removal performances were evaluated as well. An ideal experimental design was performed based on the central composite design (CCD) by RSM. In addition, this RSM was used to evaluate the effects of process variables and their interaction toward the attainment of their optimum conditions. The statistical design of the experiments and data analysis was resolved using the Design-Expert software. Further, the range of coagulant dosage and pH was selected based on a batch study which was conducted at 13 000 mg/L to 17 000 mg/L of SnCl 4 and pH ranged from 6 to 10. The results showed that the optimum pH and dosage of SnCl 4 were 7.17 and 15 g/L, respectively, where the maximum removal efficiency was 67.7% for COD and 100% for color and SS. The results were in agreement with the experimental data with a maximum removal efficiency of 67.84 %, 98.6 %, and 99.3%, for COD, color, and SS, respectively. Overall, this study verified that the RSM method was viable for optimizing the operational condition of the coagulation-flocculation process.
Treatment of Landfill Leachate through Coagulation Process
Landfill leachate can be defined as a liquid that passes through the municipal solid waste (MSW) landfill and has extracted dissolved and suspended matter from it. The generation of leachate is a major problem for MSW landfills and causes significant threat to surface water and groundwater. Special care is required for efficient treatment and disposal. In addition, landfill leachate is complex waste water with considerable variation in both quality and quantity. The composition and concentration of pollutants are influenced by the types of waste deposited, hydro geological factors and more significant by the age of the landfill site. In general, leachate is highly contaminated with organic contaminants measured as chemical oxygen demand (COD), biochemical oxygen demand (BOD) and also with high ammonium nitrogen concentration. The main focused of this research is to investigate the performance of chemical treatment by coagulation process and to compare the efficiency of coagulants on removal of COD and TSS with standard tools in leachate samples which was collected from Rajbondh landfill in Khulna. The collected leachate samples were tested in the laboratory through the standard methods to measure the relevant parameters. The characteristics of leachate were: pH=8.6; BOD5=142.1 mg/L; COD=5760 mg/L; Temperature=28.7ºC; Electric Conductivity=5.67µs/cm; TS=17000 mg/L; TDS=16600 mg/L; TSS=400 mg/L; Turbidity=336 NTU; Color=17800 pt-co; Alkalinity=1700 mg/L; Salinity=2800 mg/L; T.C.=740; F.C.=300. The coagulation of leachate was accomplished by a technique consisted of Poly-Aluminum Chloride (PAC), Aluminum Sulphate (Al 2 (SO 4) 3 .18H 2 O) as Alum and Ferrous Sulphate (FeSO 4) in various dosages and different pH values (2, 5, 7 and 9). Results showed that the efficiency for COD removal by PAC at pH=9 and 2500 mg/L of coagulant dose, by Alum at pH=9 and 2500 mg/L of coagulant dose, by Ferrous Sulphate at pH=7 and 2000 mg/L of coagulant dose. The COD removal efficiency for PAC, Alum and Ferrous Sulphate were 81.82, 75 and 85.71% respectively. Results also showed that efficiency for TSS removal by PAC that was obtained at pH=5 and 2500 mg/L concentration of coagulant dose, by alum at pH=7 and 2500 mg/L concentration of coagulant dose and by ferrous sulphate at pH=9 and 2000 mg/L of coagulant dose. The TSS removal efficiency for PAC, Alum and ferrous sulphate are 46.15, 60 and 72.73% respectively. In this study carried out the COD and TSS removal efficiency both were better for ferrous sulphate. To depict the performance of used chemical coagulations then compared to the standards leachate discharge which are available in the literature.
Dosage and pH optimization on stabilized landfill leachate via coagulation-flocculation process
MATEC Web of Conferences, 2018
Treatment on the generated landfill leachate is crucial as it can cause serious toxicological effects and environmental hazards, particularly when the unfavorable contaminants are left accumulated for a long period of time. The purpose of this study was to determine the optimum coagulant dosage of polyaluminium chloride (PAC) in selected dosage ranges (2250-4500 mg/L) and to analyse the ideal pH of leachate sample (pH 3-10). PAC was tested on stabilized leachate taken from Simpang Renggam Landfill Site (SRLS), by investigating the percentage removals of five significant parameters, which were suspended solids, chemical oxygen demand (COD), ammonia, and heavy metals (iron (Fe) and chromium (Cr)). The removal efficiency was determined by a series of experiments using jar test. From the obtained results, it was found that 3750 mg/L and pH 7 were the optimum conditions for PAC dosage and sample pH, respectively. The conventional optimization test showed satisfactory results for suspende...
Effective removal of contaminants in landfill leachate membrane concentrates by coagulation
Chemosphere, 2017
Leachate membrane concentrates containing high concentrations of organics and trace toxic compounds pose a major threat to the environment, and their treatment is an urgent issue. In this work, various coagulants were used to treat leachate membrane concentrates. Appropriate pH values for treatments with FeCl2, FeSO4, polyaluminum chloride, and FeCl3 were 3, 5, 5, and 4, respectively. FeCl3 achieved the highest total organic carbon (TOC) removal efficiency. The effect of the various anions in ferric coagulants [FeCl3, Fe2(SO4)3, and Fe(NO3)3] on the TOC removal efficiency was negligible. The main organics remaining in the leachate membrane concentrates after coagulation were humic and fulvic acids. The conditions for coagulation with FeCl3 were optimized using the response surface method (RSM). The highest TOC, chemical oxygen demand (COD), and chromaticity reduction efficiencies, 81%, 82%, and 97%, respectively, were achieved at pH 4 using FeCl3 (5 g L(-1)) and polyacrylamide (PAM;...
International Journal of Environmental Engineering, 2017
A coagulation and flocculation treatment method was applied on partially stabilised leachate of Matang landfill. The interactions and effects of dose and pH on the removal of suspended solid (SS), colour and chemical oxygen demand (COD) were investigated, analysed and optimised through RSM. The optimal condition obtained from the satisfactory mathematical model was 0.24 g/L Fe and 4.94 of poly iron chloride (PHI) dose and pH, respectively. Confirmatory experiment indicates good agreement between model prediction and experimental value. Therefore, RSM is an appropriate statistical tool in the optimisation of PHI coagulation and flocculation process.
Treatment of Landfill Leachate using Coagulation
Commercial/ conventional coagulant was used for the removal of COD and turbidity from landfill leachate containing COD 2451 mg/L. Coagulation studies were performed with lime and alum by varying parameters such as pH and coagulant dose. The experimental study shows that coagulation with calcium hydroxide and alum can remove up to 69% and 54% COD from the leachate. The optimum process variables of this coagulation study were found for calcium hydroxide and alum as pH 8 and 6; and coagulant dosage 25 g/L and 15 g/L, respectively.