Sains Malaysiana 36(1): 45-52 (2007)

Characterisation of The Leaching Behaviour of Coal Fly

Ash with Tank Leaching Test Method

(Pencirian Sifat Larut Resap Abu Terbang Arang Batu dengan

Kaedah Ujian Larut Resap Tangki)

Khoo Kok Siong & Lim Ai Ling

Pusat Pengajian Fizik Gunaan, Fakulti Sains & Teknologi

Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia

Sukiman Sarmani

Pusat Pengajian Sains Kimia & Teknologi Makanan

Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia

ABSTRACT

Characterisation of the leaching behaviour of coal fly ash from Tenaga Nasional Berhad (TNB) by using tank leaching test method has been reported. The leachability of the constituents such as major elements and toxic metals in the coal fly ash was studied. Eight renewed leachant solutions after 6 hours, 1, 2, 5, 8, 21, 36 and 64 days were investigated after filtration. The parameters namely pH, cumulative release regarding the major elements and toxic metals to duration were presented. The results showed that the pH solutions increased from pH 4 to neutral and remained stable during the test. It might have resulted from the large buffering capacity of the coal fly ashes. Five major elements namely Al, Ca, K, Mg and Na were detected with Ca concentration in the leachant solutions was the highest for all samples. Toxic metals such as As, Ba, Co, Cr, Mn, Ni, Pb, Se and Zn were found and the test showed consistent results on the As, Ba, Mn, Se and Zn in leachant solutions. The findings also showed that some of the toxic metal concentrations namely As, Ba, Cr, Pb and Se exceeded the maximum allowance of the guideline of drinking water quality in Malaysia and WHO. Obviously, proper waste management has to be applied in this scenario.

Keywords: Coal fly ash; tank leaching test; major elements; toxic metals

ABSTRAK

Pencirian bagi sifat larut resap abu terbang arang batu dari Tenaga Nasional Berhad (TNB) dengan kaedah ujian larut resap tangki telah dilaporkan. Kebolehan larut resap juzuk misalnya unsur-unsur major dan logam toksik dalam abu terbang arang batu telah dikaji. Lapan larutan luluh larut yang diperolehi selepas 6 jam, 1, 2, 5, 8, 21, 36 dan 64 hari telah dianalisis setelah penapisan. Parameter-parameter seperti pH, pembebasan kumulatif unsur major serta logam toksik terhadap tempoh masa telah dipersembahkan. Keputusan menunjukkan bahawa larutan pH meningkat dari pH 4 ke neutral dan kemudian berada dalam keadaan stabil sepanjang ujian. Hal ini mungkin hasil daripada kapasiti penampan yang beasr bagi abu terbang arang batu. Lima unsur major seperti Al, Ca, K, Mg dan Na telah dikesan dalam larutan luluh larut dengan kepekatan Ca adalah tertinggi bagi semua sampel. Logam toksik seperti As, Ba, Co, Cr, Mn, Ni, Pb, Se dan Zn juga dikesan dan ujian ini menunjukkan bahawa As, Ba, Mn, Se dan Zn dalam larutan adalah konsisten. Kajian juga menunjukkan bahawa sebahagian daripada kepekatan logam toksik seperti As, Ba, Cr, Pb dan Se telah melampaui had maksimum kualiti air minum yang digariskan oleh Malaysia dan WHO. Jelas sekali, pengurusan sisa yang sesuai perlu digunakan dalam senario ini.

Kata kunci: Abu terbang arang batu; ujian larut resap tangki; unsur major; logam toksik

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