Treatment of Mixer Truck Wash Water of a Ready-mix Concrete Batching Plant Using a Low Cost Modified Sand F

Infrastructure and housing developments require vast quantities of concrete, some of which are supplied by the ready-mix concrete (RMC) batching plant. This industry’s high water demand and wastewater generation have caused significant environmental problems. An RMC batching plant in the southern part of Bali produces liquid waste, which is disposed of into the surrounding mangrove forests after being treated using five sequential unlined wash water ponds and palm fibre. Although the COD value has been decreased from 316.149 mg/l of untreated wastewater to 146 mg/l after treatment, this still has the potential to harm the mangrove biota. On the other hand, the water can still be reclaimed for cleaning purposes or even incorporated into process water. The work aims to design a low cost and simple wastewater recycling process and equipment. Wastewater was collected from the existing settling basin at the RMC batching plant and treated in the laboratory. It was found that the chemical treatment of wastewater using alum did not produce satisfactory results; therefore a physical method was chosen by employing a sedimentation pond and modified slow sand filter. It removed 82.83% of the COD at pH 12.270 and reclaimed 84% wash water or 26.7% total water needed for this industry