Investigating the treatability of prepared food industry wastewater using the chemical process of coagulation and flocculation
Subject Areas : Water and wastewater technology
Mitra Gholami Moghadam
1
,
Fariba Ostovar
2
,
Mohadese Tavakoli
3
1 - MSc in Civil-Environmental Engineering, Higher Education Research Institute of ACECR, Rasht, Iran
2 - PhD in Analytical Chemistry, Environmental Research Institute of ACECR (Academic Center for Education, Culture and Research), Rasht, Iran
3 - Research expert, Environmental Research Institute of ACECR (Academic Center for Education, Culture and Research), Rasht, Iran
Keywords: Wastewater, prepared food industry, coagulation and flocculation, jar test, iron (III) chloride, COD,
Abstract :
This research aims to investigate the treatability of prepared food industry wastewater using the chemical process of coagulation and flocculation. Ferric chloride (FeCl3) coagulant was used in this process along with polyacrylamide and lime flocculant aids. In order to investigate the mutual effect of the parameters affecting the treatment process, the design of experiments (DOE) software with the central composite model (CCD) was used. Effecting factors on the coagulation and flocculation process such as FeCl3 coagulant concentration in the concentration range of 500-2000 mg/L, initial pH in the range of 5-10, lime and polyelectrolyte with the concentration ranges of 25-100 mg/L and 0.5-2.5 mg/L respectively were evaluated by Jartest device. Chemical oxygen demand (COD) analysis was chosen as the target test to determine the optimal values. Comparison of optimal conditions of single agent and mutual effect of data using experiment design software, an optimal value of pH equal to 7.5, FeCl3 coagulant concentration of 1250 mg/L, and coagulants of lime and polyelectrolyte with concentrations of 60 and 1.5 mg/L respectively, showed COD removal efficiency of 94.15%. Statistical analysis showed that the F-value equal to 19.48 indicates the good agreement of this model with the laboratory results. Also, P-values less than 0.050 indicate the significance of the test. By comparing the laboratory and the predicted results, a good correlation between the results was observed. Finally, the results of this research showed that it is possible to treat the wastewater of the food industry using FeCl3 coagulant, and the treated wastewater meets the standards of discharge to agricultural lands for fields irrigation
