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Design of Precipitation System for the Removal of Total Suspended Solid, Turbidity and Mineral Content from Coal Processing Plant Wastewater

Author Affiliations

  • 1Chemical Engineering Department, University of Indonesia, Kampus UI Depok 16424, INDONESIA

Res.J.chem.sci., Volume 1, Issue (5), Pages 40-47, August,18 (2011)


A precipitation system was designed for the removal of total suspended solid (TSS) from wastewater coming from a coal processing plant (CPP). The wastewater from the studied CPP had a pH in the range of 3.4-3.6 with TSS and turbidity of 1000 and 150 mg·L-1, respectively. The selection and dose optimization of the cationic coagulants (Ferric chloride (FeCland Aluminium sulphate (Al[SO4l3)), inorganic polymer coagulant (Poly Aluminium Chloride (PAC)) and a commercial coagulant (brand name (N8100)) were carried out. The results showed that N8100 at 5 mg·L-1 dose and pH 6-8 gave the best performance with the final wastewater had TSS 10 mg·L-1, Turbidity 3 mg·L-1, Fe 0.11 mg·L-1, Mn and Al each 0.01 mg·L-1 (undetectable). These results were below the limit set by the Indonesian wastewater standard for coal mining industry. The designed precipitation system used for the removal of total suspended solid consisted of equalization pond (960 m), inlet channel with baffles and coagulant-lime control for optimum mixing and three identical sedimentation ponds (each with the lower dredge volume of 105 m and the whole pond volume of 675 m). These ponds retained the sediments for 3 months prior to cleaning. Coagulants N8100, FeCl, Al(SO4 andPAC had the operating costs 10.03 US$/day(lowest) 118.95, 22.06 and 21.77 US$/day, respectively. Besides the low operating cost N8100 had produced least sediments compared to FeCl, Al(SO4)3 and PAC.


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