Water reuse for the bottled water industry

The bottled water industry uses a machine specifically designed for the washing of its containers (19-L capacity) and generates 6-L wastewater/container. This effluent can be used for watering of green areas and car washing. The objectives of the present work were to characterize the effluent and to propose a specific treatment to enable reuse of the effluent from the container washing machine. The analysis of water quality identified the following problems: high pH (10.0), high biochemical oxygen demand (50 mg/L), high concentration of free residual chlorine (3.15 mg/l), alkalinity (207 mg/l as CaCO₃) and hardness (38.8 mg/l as CaCO₃). These parameters must be reduced in order to comply with the Mexican standards for water reuse (NOM-003-ECOL-1997), and to protect the washing equipment against corrosion and incrustations. The water can be used for the watering of green areas after pH adjustment and Biological Oxygen Demand (BOD₅) removal. If special equipment is used for car washing, it is necessary to reduce the concentration of calcium and magnesium using a strong cationic resin. Following these recommendations the specific industry installed a treatment system with pH adjustment, dual filtration (sand-anthracite) and adsorption system with activated carbon. The effluent is now used for watering of green areas and for car washing with garden hoses.