The Effect of Operating Conditions on the Removal of Natural Organic Matter from Water by Coagulation and Floculation

Podzemna voda Istočne Hrvatske karakteristična je po povećanim koncentracijama organskih tvari, arsena, mangana, željeza te amonijaka te promjenjivim senzorskim svojstvima - mutnoći, boji, okusu i mirisu vode. Promjena boje vode povezano je s povećanjem prirodnih organskih tvari u vodi. Prirodne organske tvari su kompleksna smjesa organskih spojeva, a nastaju biološkom razgradnjom biljnog ili životinjskog materijala u okolišu. Podzemna voda mora proći kroz postupke prerade kako bi bila spremna za konzumiranje. Nakon prerade, kvaliteta voda se kontrolira i usklađuje s propisanim pravilnikom. Jedna od uspješnih metoda koja se primjenjuje pri uklanjanju prirodnih organskih tvari je primjena koagulacije i flokulacije. To je fizikalno-kemijski proces koji se temelji na destabilizaciji, aglomeriranju i taloženju čestica suspendiranih ili otopljenih tvari. Kod obrade vode koagulacijom i flokulacijom, ključno je izabrati odgovarajući koagulant s kojim će učinkovitost uklanjanja biti najveća. Koagulanti koji su se koristili u izradi ovog diplomskog rada su \(FeCl_{3}\) te polielektrolit. U ovom radu ispitivan je utjecaj procesnih parametara na uklanjanje prirodnih organskih tvari iz vode koagulacijom i flokulacijom. Procesni parametri koji su praćeni su koncentracija organskih tvari, suspendirane tvari, boja, ukupna tvrdoća i vodljivost te potencijal nastanka trihalogenmetana.Groundwater in Eastern Croatia is characterized by increased concentrations of organic matter, arsenic, manganese, iron and ammonia. The consequence of increased concentrations is a change in the sensory characteristics of water, ie turbidity, color, taste and smell of water. The change in color of water is associated with an increase in natural organic matter in the water. Natural organic substances are a complex mixture of organic compounds, and are formed by the biodegradation of plant or animal material in the environment. Groundwater must go through treatment processes to be ready for consumption. After all steps, the water quality is controlled and harmonized with the prescribed regulations. One of the successful methods used in the removal of natural organic matter is the application of coagulation and flocculation. It is a physico-chemical process based on destabilization, agglomeration and precipitation of particles of suspended or dissolved substances. In coagulation and flocculation, it is crucial to choose the right coagulant with which the removal efficiency will be greatest. The coagulants used in the preparation of this thesis are \(FeCl_{3}\) and polyelectrolyte. In this master's thesis, the influence of process parameters on the removal of natural organic substances from water by coagulation and flocculation was investigated. The process parameters monitored were suspended solids, color, total hardness and conductivity, and the potential for trihalogen methane formation was determined by measuring absorbances