Treatment Of Partially Stabilized Andfill Leachate Using Composite Coagulant Derived From Prehydrolyzed Iron And Tapioca Starch

Olahan larut lesapan sebelum pelepasan adalah penting bagi kesejahteraan alam sekitar. Terdapat pelbagai kaedah olahan dan pemilihan yang sesuai adalah bergantung kepada ciri-ciri larut lesapan tersebut. Antara kaedah yang selalu digunakan dan mudah adalah proses penggumpalan. Aplikasi penggumpalan-pengelompokan dalam pengurangan bahan pencemar daripada larut lesapan telah terbukti keberkesannanya. Walaubagaimana pun penggunaan bahan penggumpal kimia secara tidak langsung memberi kesan kepada kesihatan kehidupan organisma. Dalam mengurangkan kesan tersebut, penggantian bahan penggumpal kimia dengan bahan semulajadi (tepung ubi kayu (TF)) boleh diadaptasikan. Gabungan bahan penggumpal kimia dan semulajadi sebagai penggumpal komposit boleh memudahkan proses kerja dan menawarkan pelbagai kelebihan. Berbanding penggunaan besi klorida (IC), prahidrolisis besi (PHI) telah dipilih kerana ianya menawarkan lebih banyak kelebihan berbanding penggunaan besi klorida sahaja. Matlamat kajian ini adalah untuk menyiasat kebolehan bahan penggumpal komposit yang diperbuat daripada gabungan prahidrolisis besi dan tepung ubi kayu (PHITF) terhadap larut lesapan separa stabil melalui proses penggumpalan-pengelompokan. Kebolehannya dalam menyingkirkan pepejal terampai (SS), warna, Keperluan Oksigen Kimia (COD) dan ammonia dikaji. Larut lesapan separa stabil dari tapak pelupusan Matang (MLS) dan tapak pelupusan Kuala Sembeling (KSLS) telah digunakan dalam kajian ini. PHITF, PHI, PHI+TF, TF dan IC telah diuji secara berasingan bagi perbandingan kebolehannnya. Proses optimum adalah berdasarkan cara konvensional dan menerusi Kaedah Sambutan Permukaan (RSM). Melalui ujian jar, basicity terbaik adalah bagi PHI adalah 0.1 dan nisbah berat ke berat (w/w) PHITF yang terbaik adalah 0.7. Pada keadaan optimum (dos: 0.2 g/L Fe dan pH=4.71) PHITF, penyingkiran adalah 94.7%, 91.3%, 48.7% dan 6.6% bagi SS, warna, COD dan ammonia. Masing-masing pengoptimuman secara RSM, menunjukkan kebolehan PHITF adalah selari dengan PHI, PHI+TF (dua penggumpal) dan IC (besi klorida) terutama bagi penyingkiran SS, warna dan COD. PHITF mengurangkan 64% pengunaan dos daripada dos IC. Pembentukkan flok dan enap cemar adalah melalui perhubungan partikel dan penuteralan cas. Oleh itu, menghasilkan flok dan enap cemar yang lebih baik berbanding penggunaan PHI, PHI+TF dan IC. Applikasi PHITF keatas larut lesapan dari tapak pelupusan (KSLS) yang berbeza menghasilkan 96%, 91%, 69% dan 4% penyingkiran bagi SS, warna, COD dan ammonia. Ini menunjukkan PHITF boleh diaplikasikan untuk olahan larut resapan dari tapak pelupusan yang berbeza. Berdasarkan kajian, bolehlah disimpulkan bahawa PHITF boleh menjadi bahan penggumpal yang berpotensi dalam olahan larut lesapan separa stabil ________________________________________________________________________________________________________________________ Treatment of leachate before discharge is crucial to ensure the safety of the environment. Various treatment methods are available and choosing the most suitable means depends on the characteristics of the leachate. One of the most commonly adopted method is by using a coagulation process. Application of coagulation-flocculation in reducing pollutant from leachate was proven to be effective. However the use of chemical coagulant will indirectly affect the health of living organisms, thus to reduce the effect, substituting the chemical coagulant with natural material (tapioca flour (TF)) can be adapted. A combination of chemical and natural coagulant as a composite coagulant is able to simplify the process and offer many benefits. Instead of using iron chloride (IC), prehydrolyzed of iron chloride (PHI) was chosen as it offers more advantages than those offered by iron chloride alone. The aim of this study is to investigate the capability of composite coagulant made from prehydrolyzed iron and tapioca flour (PHITF) on partially stabilized leachate in a coagulation/flocculation process. The performance of this combination in removing suspended solids (SS), colour, Chemical Oxygen Demand (COD), and ammonia were investigated. Partially stabilized leachate from Matang landfill (MLS) and Kuala Sembeling landfill (KSLS) were used in this study. PHITF, PHI, PHI+TF, TF and IC were tested separately for to compare their performances. The optimization process of PHITF for pH and dose has been carried out based on conventional and response surface methodology (RSM) methods. Through a jar test, the best basicity of PHI was 0.1 and the best PHITF weight to weight (w/w) ratio was 0.7. PHITF (0.7) is characterized as acidic (pH 1.34), low conductivity (0.291 μS/m), high molecular weight (11600 KDa) and low charge density (0.245 mV). At optimum condition (dose=0.2 g/L Fe and pH=4.71) of PHITF, the removals were 94.7% for SS, 91.3% for colour, 48.7% for COD, and 6.6% for ammonia. An optimization by using RSM revealed that the performance of PHITF was at par with that of PHI, PHI+TF and IC especially on SS, colour, and COD removals. PHITF reduced 64% usage of dose from IC dose. The formation of floc and sludge of PHITF is through particle bridging and charge neutralization.. Thus, resulted in better floc and sludge formation of PHITF compared to those resulted from PHI, PHI+TF (dual coagulant) and IC (iron chloride). Application of PHITF on leachate for different landfills (KSLS) has resulted in 96%, 91%, 69% and 4% removals for SS, colour, COD, and ammonia respectively. This indicate the applicability of PHITF for the treatment of leachate from different sites of landfill. Based on the study, it can be concluded that PHITF can be a potential coagulant for the treatment of partially stabilized leachate