PHYSICAL CHARACTERIZATIONS OF PRE AND POST TREATMENT SYSTEMS OF WASTEWATER: THE CASE OF HAWASSA SOFT DRINKS INDUSTRY, ETHIOPIA

Abstract

The quality of water is a function of either or both natural and anthropogenic activities. Wastewater usually contains various pollutants, depending on what it was used for. This study was conducted to assess the pre and post soft drink industry wastewater systems and also to evaluate the effectiveness of the available and designed soil texture treatment systems at Hawassa Millennium Pepsi Cola Industry. Samples for analysis were taken at incoming water (potable water) (S1), influent (pretreatment) (S2, S3 and S4) and effluent (treated water) (S5, S6, S7 and S8) where the three effluents were discharges from the designed filtration units and one was from the existing plant. Selected seven physical quality parameters were examined by using standard methods. For most physical quality parameters the high vales at S4 influent and S5 effluent sites and low values at S2influent and S8 effluent sites were obtained. The mean result obtained from S4 influent and S5 effluent sites were pH 9.43±1.11 and 8.74±0.59, EC 1928.8±583.06 and 1801.2±507.35 µS/cm, turbidity 87.26±39.19 and 79.52±46.65 NTU, TSS 97.8±28.66 and 87±23.9 mg/L and TDS 1228.7±371.4 and 1162.14±362 mg/L respectively. One way analysis of variance (ANOVA) and the pair comparisons of group means showed significant difference (p<0.05) for most examined physical water quality parameters at most sample sites. The value of TSS 11.04 % was the highest removal efficiency at existing treatment system and the average concentrations of EC, TS, TD and TSS of the effluent from the system were significantly higher than the acceptable ranges of the discharge limits set by EEPA and WHO. However, comparatively better efficiency result values were recorded at soil texture treatment systems. The high efficiency value of turbidity 49.8 % and TSS 37.42 % were obtained at SC soil texture filtration system. The highest filtration rate 104.4 L/hr was recorded at the LS soil texture and lowest average value of 17.6 L/hr was obtained at the SC soil texture filtration system. Therefore, the result indicated the bottle washing process was significantly polluting the input water and provides more polluted influent to the treatment systems than the soft drink processing; SC soil texture has the better effect on reducing the influent physical quality than SCL, LS and the existing plant