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.
Oreščanin V, Nad K, Kukec L, Gajski A, Sudac D, Valković V. Trace element analysis of water and sediment before/after passing a waste water treatment plant. J Trace Microprobe Tech 2002;21:325-34.
Walker GM, Hanna J-A, Allen SJ. Treatment of hazardous shipyard wastewater using dolomitic sorbents. Water Res 2005;39:2422-8.
Ottosen LM, Arevalo E, Stichnothe H, Calmano W. Ferric flocks to remove Zn and Cu from dockyard wastewater. Environ Chem Lett 2006;3:164-8.
Oreščanin V, Nad K, Valković V, Mikulić N, Meštrović O. Red mud and waste base: raw materials for coagulant production. J Trace Microprobe Tech 2001;19:419-28.
Oreščanin V, Tibljas D, Valković V. A study of coagulant production from red mud and its use heavy metals removal. J Trace Microprobe Tech 2002;20:233-45.
Prasad R, Schafran GC. Characterization of tributyltin in shipyard waters and removal through laboratory and full-scale treatment. Water Res 2006;40:453-62.
Arevalo E, Calmano W. Studies on electrochemical treatment of wastewater contaminated with organotin compounds. J Hazard Mater 2007;146:540-5.
Vreysen S, Maes A, Wullaert H. Removal of organotin compounds, Cu and Zn from shipyard wastewaters by adsorption - flocculation: A technical and economic analysis. Mar Pollut Bull 2008;56:106-15.
Oreščanin V, Kollar R, Nad K. The application of the ozonation/electrocoagulation process for the treatment of wastewater from boat pressure washing. J Environ Sci Health A Tox Hazard Subst Environ Eng 2011;46,1338-45.
Oreščanin V, Mikulić N, Lovrenčić Mikelic I, Posedi M, Kampić S, Medunić g. The bulk composition and leaching properties of electroplating sludge prior/following the solidification/stabilization by calcium oxide. J Environ Sci Health A Tox Hazard Subst Environ Eng 2009;44:1282-8.
Oreščanin V, Lovrenčić I, Mikelić L, Lulić S. Applicability of MiniPal 4 compact EDXRF spectrometer for soil and sediment analysis. X-Ray Spectrometry 2008;37:508-11.
Oreščanin V, Ruk D, Kollar R, Lovrenčić Mikelić I, Nad K, Mikulić N. A combined treatment of landfill leachate using calcium oxide, ferric chloride and clinoptilolite. J Environ Sci Health A Tox Hazard Subst Environ Eng 2011;46:323-8.
Pravilnik o graničnim vrijednostima emisija otpadnih voda [Regulations on limit values of the emission of wastewaters, in Croatian]. Narodne novine 87/2010.
Oreščanin V, Kopjar N, Durgo K, Elez L, Findri-Guštek, S, Franekić Colić J. Citotoxicity status of electroplating wastewater prior/after neutralization/purification with alkaline solid residue of electric arc furnace dust. J Environ Sci Health A Tox Hazard Subst Environ Eng 2009;44:273-8.
Durgo K, Horvat T, Oreščanin V, Mikelić L, Franekić Colić J, Lulić S. Cytotoxicity and mutagenicity study of waste and purified water samples from electroplating industries prepared by use of ferrous sulfate and wood fly ash. J Environ Sci Health A Tox Hazard Subst Environ Eng 2005;40:949-57.
Horvat T, Vidaković-Cifrek Z, Oreščanin V, Tkalec M, Pevalek-Kozlina B. Toxicity assessment of heavy metal mixtures by Lemna minor L. Sci Total Environ 2007;384:229-38.
Gajski G, Oreščanin V, Garaj-Vrhovac V. Cytogenotoxicity of sewage sludge leachate before and after calcium oxide based solidification in human lymphocytes. Ecotoxicol Environ Saf 2011;74:1408-15.
Medley CN, Clements WH. Responses of diatom communities to heavy metals in streams: the influence of longitudinal variation. Ecol Appl 1998;8:631-44.
Clements WH, Kiffney PM. The influence of elevation on benthic community responses to heavy metals in Rocky Mountain streams. Can J Fish Aquat Sci 1995;52:1966-77.
Calabrese A, Collier RS, Nelson DA, MacInnes JR. The toxicity of heavy metals to embryos of the American oyster Crassostrea virginica. Mar Biol 1973;18:162-6.