title: Boat pressure washing wastewater treatment with calcium oxide and/or ferric chloride.
abstract: The aim of this study was to investigate the efficiency of (1) chemical precipitation by calcium oxide, (2) coagulation/flocculation by ferric chloride (FC), and (3) the combination these two methods in reducing the toxicity of wastewater generated by boat pressure washing. All three methods gave satisfactory results in the removal of colour, turbidity, Cr, Fe, Cu, Zn, and Pb. The concentrations of heavy metals were lowered below national limits with 1 g of CaO, 2.54 mg of Fe3+ in the form of FeCl3x6H2O, and the combination of 0.25 g of CaO and 5.08 mg of Fe3+ per 50 mL of wastewater. Both CaO (1.50 g per 50 mL of wastewater) and FC proved efficient, but their combination yielded a significantly better performance: 99.41 %, 100.00 %, 97.87 %, 99.09 %, 99.90 %, 99.46 % and 98.33 % for colour, turbidity, Cr, Fe, Cu, Zn, and Pb respectively. For colour, Cr, Cu, Zn, and Pb removal efficiencies increased in the following order: FC<CaO<CaO+FC, while this order for turbidity and Fe was as follows: CaO<FC<CaO+FC. As expected, all three methods increased the concentration of total dissolved solids in the final effluent. Our results suggest that the combined treatment of marina wastewaters with calcium oxide followed by ferric chloride is efficient, cost-effective, and user-friendly.
authors.affiliation: Advanced Energy Ltd., Zagreb, Croatia. vorescan@gmail.com
authors.forename: Višnja
authors.initials: V
authors.lastname: Oreščanin
authors.forename: Robert
authors.initials: R
authors.lastname: Kollar
authors.forename: Karlo
authors.initials: K
authors.lastname: Nađ
authors.forename: Ivanka Lovrenčić
authors.initials: IL
authors.lastname: Mikelić
authors.forename: Nenad
authors.initials: N
authors.lastname: Mikulić
mesh_terms: D017610:Calcium Compounds; D011232:Chemical Precipitation; D002712:Chlorides; D005290:Ferric Compounds; D005427:Flocculation; D019216:Metals, Heavy / Q000302:isolation & purification*; D010087:Oxides; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification
chemical_list: D017610:Calcium Compounds; D002712:Chlorides; D005290:Ferric Compounds; D019216:Metals, Heavy; D010087:Oxides; D014874:Water Pollutants, Chemical; C016538:lime; C024555:ferric chloride