Exploring zero discharge potentials for the sustainability of a bottle washing plant

Abstract

The beverage industry which requires large amounts of good quality water in their processes is a major contributor to the problem of excessive pumping from existing aquifers in Thailand. In view of a government restriction on groundwater withdrawal, an overall water management plan was drawn for the sustainability of a softdrink plant in Bangkok which depends solely on a deepwell source for its water needs. Technologies that can recover water for reuse, minimize raw water input and consequently lead to zero discharge were identified. The overall water balance drawn for this plant revealed that 76% of the raw water consumed daily ends up in the biological wastewater treatment plant (WWTP). A large portion (40%) of this wastewater is generated from the bottle-washing units. By employing microfiltration for polishing of the WWTP effluent, the plant can recover process water for reuse such that, groundwater input is reduced by 40% and liquid discharged to the receiving water by 56%. There are two proposed strategies for recovering rinse water from the bottle-washing units. A microfiltration-reverse osmosis system will purify the rinse water for reuse in the bottle washing process, thereby reducing raw water consumption further to 58% and the liquid discharge by 81.5%. On the other hand, a dual filter media-ion exchange system can reduce raw water input to 57% and the liquid discharge by 80.5%.