The daily emission of heavy metals into the environment is the result of human activity, most often industry, mining, inadequate disposal and waste incineration, as well as application of pesticides and artificial fertilizers. Such anthropogenic sources significantly pollute water in nature, therefore is necessary to find an ecologically and economically suitable method for heavy metals removal from water. In this diploma thesis, the possibility of using solid waste/by-products (olive pits, olive pomace pellets, remains of sea urchin, cherry pits and sour cherry pits) from local plants for food production and processing as biosorbents in the treatment of wastewater contaminated with zinc (co = 193.9 mg/L) was investigated. Zinc sorption was carried out by a batch process during 24 h, with solid/liquid ratios in the range S/L = 0.25/50 - 2.5/50. All tested biosorbents showed a certain potential for purifying zinc-contaminated water. The highest removal efficiency for all biosorbents was achieved at the highest S/L ratio of 2.5/50, as follows: 69.5% for cherry pits, 46.8% for olive pits, 35.8% for the remains of sea urchin, 29.0% for olive pomace pellets and 26.8% for cherry pits. Despite the high removal efficiency of ≈ 70% on cherry pits, the residual zinc concentration of 59.1 mg/L is higher than the maximum permissible concentration of 2 mg/L, according to the Croatian legislation for the discharge of treated water into the public sewage system and into natural recipients. Future research should be focused on reducing zinc concentration below the prescribed value. Using solid waste/by-products for the stated purpose would reduce its original amount that could end up in a landfill, and by burning saturated biosorbents under controlled conditions, it would be possible to obtain energy from waste. Such a way of using waste would reduce the total costs of water treatment and contribute to the principles of sustainable development and zero waste.