Mogućnost primene i efikasnost elektrokoagulacione tehnike u preradi podzemne vode sa visokim sadržajem prirodnih organskih materija

Abstract

<p>Osnovni cilj ove disertaciji&nbsp; bio je&nbsp; ispitivanja, mogućnosti primene, efikasnosti i ekonomske&nbsp;isplativosti EKF tehnike u preradi podzemne vode sa visokim sadržajem prirodnih organskih materija&nbsp;i arsena&nbsp; u laboratorijskim uslovima. Predment ispitivanja &nbsp;bio je protočni EKF reaktor horizontalnog&nbsp;toka pločastih elektroda od aluminijuma u bipolarnom režimu rada. EKF reaktor je projektovan,&nbsp;napravljen, a operativni parametri rada reaktora su optimizovani. Mogućnost primene funkcionalnost&nbsp;i nivo efikasnosti uklanjanja POM i arsena iz podzemne vode ispitana je u okviru dve faze&nbsp;<br />istraživanja. U okviru prve faze istraživanja izvr&scaron;ena je optimizacija parametara rada i ispitivanje&nbsp;nivoa efikasnosti EKF reaktora pri uklanjanju huminskih materija iz sintetičkog rastvora&nbsp; Fluka&nbsp;komercijalne huminske kiseline (CAS N_o&nbsp; 1415&nbsp; &ndash;&nbsp; 93&nbsp; &ndash;&nbsp; 6) &nbsp;dok je u drugoj fazi kori&scaron;čena&nbsp; podzemne&nbsp;vode iz akvifera vodosnabdevanja grada Zrenjanina.</p><p>Na osnovu svih rezultata istraživanja može se zaključiti, da se upotrebom kontinualne EKF&nbsp;tehnike energetski efikasno može smanjiti sadržaj&nbsp; prirodnih organskih materija i arsena u podzemnoj&nbsp;vodi.&nbsp; Proces predozonizacije značajno je unapredio efikasnost EKF reaktora ne samo u pogledu&nbsp;efikasnosti uklanjanja prirodnih organskih materija već i u smanjenju specifične potro&scaron;nje električne&nbsp;<br />energije i specifične potro&scaron;nje mase aluminijumskih elektroda. Maksimalno relativno smanjenje&nbsp;UV254&nbsp; apsorbancije, DOC, od oko 82%, 71%, respektivno u odnosu na početne vrednosti UV_254&nbsp;apsorbancije, DOC podzemne vode postignuto je pri dozi ozona od 0.68 mg O3/mg DOC i sledećim&nbsp;operativnim parametrima EKF reaktora:<br />o&nbsp; vrednosti protoka tretiranog rastvora kroz reaktor od 4.3 l/h;<br />o&nbsp; korigovanoj pH vrednosti podzemne vode na 5.0;<br />o&nbsp; rastojanja izmeĎu aluminijumskih elektroda reaktora od 1.2 cm;<br />o&nbsp; vrednosti odnosa A/V reaktora od 0.248 cm^-1;<br />o&nbsp; oprativna gustine struje reaktora 5.78 mA/cm²;<br />o&nbsp; specifičnoj dozi aluminijuma od 75 g Al/m³;<br />o&nbsp; specifičnoj potro&scaron;nji energije reaktora od 1.66 kWh/m³.</p><p>Osnovni nedostak rada EKF reaktora u geometriji kori&scaron;ćenog protočnog EKF reaktora&nbsp;<br />predstavljala je koncentracija rezidualnog aluminijuma u tretiranoj podzemnoj vodi koja je oko 7&nbsp;puta (1.55&nbsp; &plusmn;0.20 mg/l) bila vi&scaron;a od makimalno dozvoljene koncentarcije (0.2 mg/l na osnovu Sl. List&nbsp;SRJ 42-98).&nbsp; Dodatna optimizacija operativnih parametara &nbsp;rada reaktora (vrednost protoka, rastojanje&nbsp;između&nbsp; elektroda) u ovoj fazi istraživanja nije rezultovala smanjenjem koncetracije rezidualnog&nbsp;aluminijuma u tretiranoj podzemnoj vodi.</p>

<p>The aim of this research was to investigate possibility of appliance and the efficiency of&nbsp;electrocoagulation/flotation (ECEF) in the treatment of groundwater with the high concentration of&nbsp;natural organic matter and arsenic under laboratory conditions. A continuous electrocoagulation-electroflotation (ECEF) reactor was designed, built, operated and its operational parameters have&nbsp;been optimised. The influence of the ECEF reactor operational parameters such as, flow rate, A/V&nbsp;ratio, interelectrode distance and current density as&nbsp; well as conductivity and the initial pH of the&nbsp;solution were investigated and optimized in two phases of research. In the first phase of research the&nbsp;performance of the ECEF reactor has been evaluated using a synthetic humic substances solution&nbsp;Fluka (CAS&nbsp; No. 1415-93-6). In the second research phase &nbsp; the performance of the ECEF reactor has&nbsp;been evaluated using groundwater samples which are taken from the City of Zrenjanin groundwater&nbsp;sources.</p><p>All results of this study has showed that ECCF treatment is a&nbsp; promising energy efficient&nbsp;purification technology for the treatment of groundwater containing high concentrations of NOM and&nbsp;arsenic. The processes of groundwater ozonation before ECEF treatment has shown positive effect&nbsp;on NOM electrocoagulation/flotation removal efficiency as well as has shown positive effect on&nbsp;reduction of ECEF reactor specific electric energy and aluminum electrode consumption. The highest&nbsp;NOM removal according to UV₂₅₄ absorbance and DOC was 82% and 71%, respectively, (relative to&nbsp;raw groundwater) as well as arsenic removal efficiency of 85% (6.2 &micro;g As/l), meeting the drinking&nbsp;water standards of 10 &micro;g/l was achieved with ozone doze of 0.68 mg O3/mg DOC and the following&nbsp;reactor operation parameters: current density 5.78 mA/cm², applied potential 17 V, inter electrode&nbsp;distance 1.2 cm, flow rate 4.3 l/h, A/V ratio 0.248 cm^-1, initial groundwater pH value 5.0. The&nbsp;specific reactor electric energy and electrode consumption were 1.66 kWh/m3 and&nbsp; 75 g Al/m³,&nbsp;respectively.</p><p>The basic lack of the continuous ECEF reactor used in this research was residual concentration of&nbsp;aluminium in the treated groundwater which was 7 times higher (1.55&nbsp; &plusmn;0.20 mg Al/l) than the&nbsp;maximum allowed concentration according to the Serbian low (0.2 mg Al/l ). Additional optimization&nbsp;150&nbsp;of the reactor operational parameters flow rate, electrode distance and ozone doze in this phase of&nbsp;research didn&rsquo;t result in the reduction of the residual aluminum concentration of treated groundwater.</p>