Optimization of coagulation pretreatment of raw water rich in natural organic matter

Istraživan je postupak optimiranja modificirane koagulacije pomoću faktorskog plana pokusa i metode odzivne površine na uzorcima podzemne vode. Istovremeno se pratio utjecaj pH vrijednosti uzorka i koncentracija koagulanata na sadržaj otopljenog organskog ugljika kao surogatnog parametra prisutnosti prirodne organske tvari u vodi. Korišteni su anorganski koagulanti željezo(III) klorid i aluminij-sulfat bez dodatka polimernih flokulanata. Učinkovitost uklanjanja prirodne organske tvari analizirana je pomoću računalnog programa Design Expert 7. Rezultati dobiveni regresijskom analizom dali su parametre maksimalnog uklanjanja otopljenog organskog ugljika. Uz korištenje željezo(III) klorida pri koncentraciji od 50 mg∙L-1 i pH vrijednosti 5,15 pokazalo se da je količina uklonjenog otopljenog organskog ugljika 69%.A bench-scale study was conducted to evaluate the effectiveness of enhanced coagulation using full factorial design of experiment and response surface method. The jar tests were performed on groundwater samples. The impact on the concentration of dissolved organic carbon was monitored with prior pH adjustment and by varying coagulant dosage. Inorganic coagulants – ferric chloride and aluminum sulfate were used without the addition of polymer as a flocculant aid. The natural organic matter removal efficiency was analyzed using Design Expert 7. Ferric chloride showed optimal results at the concentration value of 50 mg∙L-1 with prior pH adjustment to 5,15. The dissolved organic carbon removal was 69%