Rawatan untuk air sisa adalah salah satu masalah utama yang dihadapi oleh
pengusaha kilang minyak sawit. Salah satu industri kilang minyak sawit terdapat di
Sungai Kecil, Nibong Tebal, Pulau Pinang. Kilang kelapa sawit di Malaysia
mengalami kepekatan COD, warna, kekeruhan, pepejal terampai dan nitrogen
berammonia yang tinggi dalam efluen yang akhir selepas rawatan biologi yang
melebihi had pelepasan piawai. Tujuan kajian ini adalah untuk mengenal pasti
kesesuaian penggunaan batu kapur mentah (LS) dan batu kapur kalsin (CLS) sebagai
media turasan berkos rendah bagi pasca rawatan efluen terawat dengan
menggunakan turasan kasar mendatar. Rawatan fiziko-kimia yang digunakan dalam
kajian ini telah dipilih berbanding kaedah lain kerana lebih ringkas, mudah
diselenggara dan mudah bagi kawalan kualiti. Kolam akhir bagi rawatan efluen
kilang minyak sawit adalah kolam penyudah dimana efluen terus dilepaskan ke
dalam sungai. Efluen dalam kolam penyudah telah dipilih menjadi sampel dalam
kajian ini. Julat kepekatan minima dan maksima bagi kekeruhan, COD, warna,
pepejal terampai dan nitrogen berammonia dalam kolam penyudah adalah
masing-masing 200 - 650 NTU, 2,200 – 3,300 mg/L, 3,000 – 5,000 PtCo, 400 - 730 mg/L
dan 190 – 300 mg/L. Saiz partikel bagi batu kapur iaitu 4, 12 dan 20 mm;kadar
aliran seperti 20mL/min, 60mL/min, dan 100mL/min; dan suhu iaitu 400 ˚C, 600 ˚C
dan 800 ˚C, telah digunakan dalam kajian ini. Hasil menunjukkan partikel media
bersaiz kecil (4mm) lebih berkesan daripada partikel bersaiz besar (20 mm) kerana
partikel bersaiz kecil mempunyai luas permukaan yang lebih tinggi yang menyebabkan
kapasiti penjerapan tinggi. Selain itu, kadar aliran rendahmenyebabkan masa
penepuan tinggi, manakala kadar aliran tinggi memendekkanmasa penepuan turus
dan menunjukkan penyingkiran yang kurang berkesan. Kajianmenunjukkan bahawa
batu kapur kalsin pada suhu 800 ˚C mempunyai kecekapan penyingkiran yang paling
tinggi bagi kekeruhan, COD, warna, pepejal terampai dannitrogen beramonia
(66%, 50%, 52%, 60%, 75%, masing-masing) pada media turasan bersaiz kecil (4 mm)
dan pada kadar aliran 20 mL/min berbanding batu kapur kalsin pada suhu berbeza dan
juga batu kapur mentah. Hasil kelompok menunjukkan dos optimum bagi batu kapur
kalsin pada suhu 800 ˚C untuk menyingkir kekeruhan, COD, warna, pepejal terampai
dan nitrogen beramonia (69.23%, 48.23%, 40.13%, 70.81%, 50%, masing-masing) adalah
85 g dos batukapur; manakala masa pengenapan optimum adalah 5 jam. Kecekapan
penyingkiran paling tinggi diperolehi pada keadaan berasid bagi semua parameter,
tetapi NH3-N disingkirkan dengan berkesan pada pH 10 (58.17%) bagi batu kapur kalsin
pada suhu 800 ˚C. Data penjerapan keseimbangan untuk kekeruhan, COD, warna,
pepejal terampai dan nitrogen beramonia (0.959, 0.916, 0.935, 0.909, 0.977,
masing-masing) lebih padan dengan isoterma Langmuir berbanding isoterma Freundlich
kerana nilai R2 lebih tinggi.
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Treatment of wastewater is one of the major problems faced by palm oil mill
operators. One of the palm oil mill industries in Sungai Kecil Nibong Tebal, Pulau
Pinang, Malaysia is experiencing a high concentration of turbidity, COD, colour,
suspended solid and ammoniacal nitrogen in the final effluent after biological
treatment that exceeds the standard discharge limit. The purpose of the present study
is to investigate the suitability of using raw and calcinated limestone as low cost
filter media for the treatment of treated effluent by using horizontal roughing filter.
The physico-chemical treatment adopted in this study is preferred over other methods
because of its simplicity, easy maintenance and quality control. The last treatment
pond of palm oil mill effluent is the polishing pond where wastewater is directly
discharged to the river. The polishing pond was selected for sampling in this study.
The minimum and maximum concentrations of turbidity, COD, colour, suspended
solid, and ammoniacal nitrogen in the polishing pond were 200 - 650 NTU, 2,200 –
3,300 mg/L, 3,000 – 5,000 PtCo, 400 - 730 mg/L, and 190 – 300 mg/L respectively.
The parameters used in this study were particle sizes of limestone of 4, 12 and 20
mm, flowrates of 20 mL/min, 60 mL/min, and 100 mL/min and temperatures of 400
˚C, 600 ˚C and 800 ˚C. Results indicated that a smaller particle size of limestone (4
mm) was more effective than a larger particle size of limestone (20 mm) because
smaller sized particles of filter media have higher surface area which leads to high
adsorption capacity. In contrast, a low flow rate (20mL/min) results in higher column
saturation time, while higher flow rate results in shorter column saturation time and
shows low removal efficiency. The study indicated that calcinated limestone at 800
˚C has the highest removal efficiency for turbidity, COD, colour, SS and NH3-N
(66%, 50%, 52%, 60% and 57% respectively) at smaller sized filter media (4 mm)
and lower flow rate (20 mL/min) compared to calcinated limestone at different
temperature and raw limestone. The batch results showed that the optimum dosage of
calcinated limestone at 800 ˚C for removing turbidity, COD, colour, SS and NH3-N
(69.23%, 48.23%, 40.13%, 70.81%, 50% respectively) was 85 g, whereas the
optimum settling time was 5 hours. High removal efficiency was obtained in acidic
phase for all parameters, but NH3-N was removed efficiently at pH 10 (58.17%) for
calcinated limestone at 800 ˚C. The equilibrium adsorption data for turbidity, COD,
colour, SS and NH3-N (0.959, 0.916, 0.935, 0.909, 0.977 respectively) was wellfitted
with the Langmuir isotherm compared to that of Freundlich isotherm, indicated
by high R2 value for small sized calcinated (800 ˚C) limestone.
Treatment of palm oil mill effluent from polishing pond using calcinated limestone roughing filter_Arezoo Fereidonian Dashti_A9_2017_MYMY