Modeling Jambo wastewater treatment system to predict water re-use options

Abstract

The harmful nature of chemicals used in the tannery industries and the disposal of wastes from facilities is well documented. In this study, Jambo tannery which is located in Busia District, (Uganda) with a daily processing capacity of 6.6 tonnes of hides and skin utilises 20 m³ of water to produce 17 m³ of wastewater/day. The generated wastewater is treated on site in the wastewater treatment plant whose performance was assessed. The main objective of this study was twofold: (i) to investigate how processes can be efficiently improved and optimized for environmental safety, and (ii) to develop Dev C⁺⁺ programme to implement Brown’s model for determining water quality usage of the effluent of the factory. Specifically, wastewater parameters measured were temperature (T), electro conductivity (EC), pH, total suspended solids (TSS), total dissolved solids (TDS), biological oxygen demand (BOD5), chemical oxygen demand (COD), total phosphorus (TP), total chromium (TCr), chromium hexavalent (Cr⁶⁺) and chromium trivalent (Cr³⁺). The results of the tannery wastewater were far from the National Environment Management Authority (NEMA) standards in Uganda for COD (100), BOD5 (50), TP (10), TC (2.0), CH (0.05), TSS (100), TDS (1200), EC (1500) and pH (6.0-8.0). It can therefore be concluded that the performance of the wastewater plant is not satisfactory in the current state. The effluent quality is therefore not currently suitable for release in the environment and re-use for Agricultural and Domestic purposes as per National Environmental Management Authority (NEMA) Standards 1995. However, with improvements in the WWTP unit operations, it could be improved, re-used for irrigation. As such, a model was developed to model wastewater system to predict re-use options especially for agriculture. The study clearly showed that the use of the model and the developed C⁺⁺ computer programme in predicting the re-use options of the wastewater treatment system was a success and can be applied to other wastewater treatment system as well as improving and managing the existing one.

 Key words: Wastewater treatment, tannery effluent, water standards, water quality, environment safety.