Pretreatment of Olive oil Wastewater by Coagulation-Flocculation Method and Xanthan Production

In this research, the production of xanthan biopolymer in two substrates of olive mill wastewater (OMW) and pre-treated OMW by coagulation -flocculation methods was investigated. Aluminum, iron ions, and lime have been used as coagulants . The use of 4 g/L FeCl3 has caused the highest removal efficiency of COD and PPH about 24 and 31% respectively. Considering the reasonable price of lime and its effect in creating alkalinity the combination of various coagulants with lime was also investigated. The results show that the combination increases the pollutant removal efficiency by two folds and also reduces the amount of coagulant consumption. For example, the combination of 4 g/L of lime with 3 g/L of FeCl3 removes 48 and 65 percent of COD and PPH, respectively. In order to investigate the effect of reducing the concentration of PPH on the xanthan production , the growth of the microorganism Xanthomonas campestris and the production of xanthan in different concentrations of raw OMW and pre-treated OMW were investigated. The results show that the pre-treatment process increases the xanthan production. So that the maximum amount of xanthan produced in raw OMW at the concentration of 40% is equal to 4 g/L, and this much in pre-treated OMW is 13 g/L at a concentration of 70%. Therefore, the use of pre-treatment methods and the reduction of toxic biological compounds in OMW, in addition to the significant increase in the amount of xanthan produced, also leads to a decrease in the dilution of the wastewater.