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Coagulation-Flocculation in Leachate Treatment Using Combination of PAC with Cationic and Anionic Polymers

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Coagulation-Flocculation in Leachate Treatment Using Combination of PAC with Cationic and Anionic Polymers Zawawi Daud, Zawawi Daud, Abd Aziz Abdul Latif, Lee Mao Rui/ International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue4, July-August 2012, pp.1935-1940 Coagulation-Flocculation In Leachate Treatment Using Combination Of PAC With Cationic And Anionic Polymers 1 Lee Mao Rui, 2 Zawawi Daud,3 Abd Aziz Abdul Latif F. A. Author is with the Civil Engineering Department, University of Tun Hussein onn, 86400 Parit Raja, Batu Pahat, Johor, Malaysia. (corresponding author to provide phone: 012-6780167; S. B. Author, was with Civil Engineering Department, University of Tun Hussein onn, 86400 Parit Raja, Batu Pahat, Johor, Malaysia T. C. Author is with the Civil Engineering Department, University of Tun Hussein onn, 86400 Parit Raja, Batu Pahat, Johor, Malaysia. Abstract A study was conducted to treat the Heavy metals are a concern due to their adverse effect leachate through coagulation-flocculation. on the environment, through very low concentration Polyaluminium chloride (PAC) was used as of Heavy metals are observed in the methanogenic(Li coagulant with cationic and anionic polymers as et al 2010). coagulant aids. The results were subsequently Leachate composition varies significantly compared with the study in which PAC was used among landfills, depending on waste composition, alone for the treatment. Jar test apparatus was waste age, climate, hydrogeological conditions and used to conduct research work. The results of the land filling technology. The main characteristic of study revealed that the combination of PAC with landfill leachate is high concentration of organic cationic polymer resulted in optimum for matter and as a result, high concentration of BOD and suspended solid (SS) removal of 99.2%, color COD. The management of leachate is among the most removal of 89.8%， COD removal of 59% and important factors to be considered in planning, ammoniacal nitrogen removal of 49%. The designing, operation, and long term management of combination of PAC with anionic polymer resulted municipal solid waste (MSW) landfill (Rivas et al, in optimum for SS removal of 99%, color removal 2004). of 89.4%, COD removal 56% and ammoniacal Leachate treatment technique can be nitrogen 46%. The results of the above classified as combined treatment with domestic combinations were compared with those when sewage, biological treatment and physic-chemical PAC was used alone for the treatment. methods. Selections of the most appreciate method for leachate treatment is very important but often difficult because of the highly variable quantity and quality of keywords—coagulation-flocculation, leachate, landfill leachate (Sartaj et al., 2010, Bashir, et al., coagulant, polymer 2011). Sanitary landfill is defined as a land disposal I. INTRODUCTION site that applies an engineered method of disposing of Landfill leachate is defined as any solid wastes on land in a manner that minimizes contaminated liquid effluent percolating through environmental hazards by spreading the solid wastes deposited waste and emitted within a landfill or dump to the smallest practical volume, and applying and site through external sources, of which its route of compacting cover material at the end of each day. exposure and toxicity often remains unknown. Sanitary landfilling is an acceptable and Throughout recent decades, the wastewater treatment recommended method for ultimately disposing of industry has identified the emission of organic, solid waste. The sanitary landfill is an engineered inorganic and heavy metals compounds due to landfill that requires sound and detailed planning and leachate seepage into the waterways as a risk the specification, careful construction, and efficient natural environments (Ghafari et al., 2010). operation (Al – Abdali et al., 2008, Al – Yaqout et al., Landfill leachate can be a significant 2005). environmental contaminant if it leaves the landfill site, Coagulation-flocculation is a relatively which can occur if the site is designed as a dilute and simple technique that may be employed successfully disperse site, if the landfill is unlined or if the landfill for the treatment of landfill leachate. The removal is lined but the lining fails. Typically, leachate that mechanism of this process mainly consists of charge leaves a landfill site will enter the ground water as a neutralization of negatively charged colloids by contaminant plume, where it is then diluted and also cationic hydrolysis products, followed by transformed by a variety of processes such as sorption, incorporation of impurities in an amorphous chemical precipitation and microbial degradation. hydroxide precipitate through flocculation (Wang et 1935 | P a g e Zawawi Daud, Zawawi Daud, Abd Aziz Abdul Latif, Lee Mao Rui/ International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue4, July-August 2012, pp.1935-1940 al., 2009). aluminum chloride with organic polymers. The iron coagulants include ferric sulfate, ferrous sulfate, ferric II. COAGULATION-FLOCCULATION chloride, ferric chloride sulfate, poly ferric sulfate, and ferric salts with organics polymers (Gurses et al., Coagulation-flocculation has been employed 2003; Casey., 1997). for the removal of non-biodegradable organic compounds and heavy metals from landfill leachate. C. Polyaluminium chloride (PAC) The coagulation process destabilizes colloidal PAC is a group of highly effective coagulants particles by the addition of a coagulant. Coagulation is in water treatment that have replaced a large part of usually followed by flocculation of the unstable traditional aluminous coagulants because of low particle into bulky floccules so that they can settle dosage, high efficiency, low cost and convenient more easily. The general approach for this technique usage. In order to improve the coagulation efficiency includes pH adjustment and involves the PAC as the and to suit different conditions, many sorts of PAC coagulant to overcome the repulsive forces between with different organic polymers has been investigated. the particles (Gnandi et al., 2005; Tatsi et al., 2003). It is more effective coagulation species in In water treatment, coagulation and polyaluminum coagulants due to its strong charge flocculation are still essential components of the neutralization capability, high structure stability and overall suite of treatment processes. From an nanometer molecular diameter (Li et al., 2010; Zhang engineering survey of the quality of water treatment at et al., 2008). water treatment plants, the chemical pretreatment Polymer as a coagulant aids in the treatment prior to filtration is more critical to success than the of water and wastewater. It also used as primary physical facilities at the plant. Coagulation and coagulant for the same treatment. Generally, a little flocculation are useful because the flocculated amount of polymer dosage is enough to reach high particles can reduce fouling by producing more efficiency. Cationic polymer was the most effective permeable deposits (Gnandi et al., 2005; Golob et al., followed by anionic and non-ionic (Zahrim et al., 2005). 2011). The improvement in removal by PAC while The removal of SS, color, COD and using polymers as a coagulant aids was studies by ammoniacal nitrogen form stabilized leachate was varying the PAC dose and adding a fixed dose of a investigated using coagulation with PAC and polymer. The optimal combination of PAC and polymers. pH and coagulant dosage has been observed polymers doses that fixed 2000 mg/L PAC and use 5 to significantly affect to efficiency of coagulation and mg/L for cationic polymer or anionic polymer. All flocculation process. The best conditions for these polymers were in dry form and it were prepared coagulation and flocculation tests on SS, color, COD in 1% solution by using distilled water. and ammoniacal nitrogen removal are evaluated and optimized (pH and coagulant dosage) by a jar test D. Polymers technique. The first, effect of pH values and then Polymers refer to a large variety of natural or coagulant and coagulant aids dosage on the efficiency synthetic, water soluble, macromolecular compounds, was evaluated. The optimum pH for the treatment was which have the ability to destabilize or enhance determined. The study was carried out between the pH flocculation of the constituents of a body of water. values of 2 -12. Desired pH values of leachate were Although natural polymers products have the adjusted by using H2SO4 and NaOH. advantage of being virtually toxic free, the use of synthetic polymers is more widespread (Sun et al., III. MATERIAL 2011). This experiment aims to identify the A. Sampling effectiveness and capabilities of polymers to increase Leachate samples were collected from Pasir the percent removal of suspended solids (SS), color, Gudang sanitary landfill, Pasir Gudang, Johor, COD and ammoniacal nitrogen (NH3N) in the Malaysia. Leachate was collected from the leachate leachate sample. Two types of coagulant aids were collection pond. The sample was the raw sample and it used in this part that was cationic polymer FO4290 SH was without any treatment. and anionic polymer AN934 SH. B. Coagulant IV. COMPOSITION AND CHARACTERISTICS OF The commonly used metal coagulants fall LEACHATE into two general categories: those based on aluminum Leachate tends to percolate downward and those based on iron. The aluminum coagulants through solid waste, continuing to extract dissolved or include aluminum sulfate, aluminum chloride,
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