Teollisuuden jätevedenkäsittelyn optimoinnin tapaustutkimus kestävän kehityksen saavuttamiseksi

Industrial wastewater treatment plants are increasingly facing challenges for demands to meet more stringer discharge limits. Treatment plants that have been designed decades ago are more likely to have challenges to improve effluent quality without capital investments. Optimization can provide a solution to enhance treatment performance as well as to maximize the capability of the existing process performance. This thesis researches the optimization of a chemical treatment process through pH, bentonite and contact time. The studied wastewater sample was originated from real industrial wastewater from metal packaging industry and can be characterized by low pH, aluminium, sulphate, fluoride, COD and surfactants. Laboratory scale jar tests were conducted, and central composite design was used for analysis of the combined effects of pH, bentonite and contact time on pollutant removal. Results showed that pH and bentonite dosing had statistically significant impact to the removal of COD, fluoride, and surfactants from wastewater. Contact time had less significant impact within the studied range. Fluoride removal is dependant of the pH showing non-linear behaviour. Aluminium concentration is highly sensitive to pH where precipitation occurs near neutral condition. The use of multi-response optimization showed that pollutants could not be optimized individually because it would have compromised other parameters and therefore needed to be balanced within the operating window to ensure all key process parameters are complying the regulations.