Industrial Strength Reuse: Utilizing MBR+RO To Reduce Water Consumption By 70 Percent At A Tractor Manufacturing Facility

Membrane bioreactor (MBR) treatment has been applied to the industrial wastewater produced by the coating process at Kubota Industrial Equipment (KIE) in Jefferson, GA, as well as domestic wastewater from the office building. By adding a reverse osmosis (RO) skid downstream of the MBR, the effluent can be recycled. The total treated effluent is reused for the coating pre-treatment process; 27,000 gal/day is reused for the manufacturing process, reducing the need of public water from 37,000 to 10,000 gal/day (70% reduced by water reuse). The total reuse cycle can be seen in Figure 1. This system saves on total water consumption as well as operational costs incurred by water use in the coating process. The total wastewater is a combination of domestic grey water from the office building and pre-treated wastewater from the tractor coating process, that can produce up to 23,000 mg/L of BOD and 9,360 mg/L TSS. Industrial wastewater is pre-treated for oils and heavy metals by coagulation and pH adjustment, followed by a gas energy mixing system where solids and liquids are separated by flotation. The pre-treated industrial wastewater and office building grey water are then combined in an equalization tank and subjected to MBR. MBR treatment is accomplished in conjunction with an AO biological treatment with a single recycle from the membrane tank to the anoxic tank. Kubota microfiltration flat sheet submerged membrane units are employed in the membrane tank. BOD and TSS are treated by MBR to near non-detect levels; however total dissolved solids require further treatment. Therefore, the MBR effluent is treated by dual stage RO that can accomplish a reduction in electrical conductivity up to 99% (619 µS/cm influent, 4.75 µS/cm effluent). See a detailed illustration of the process flow in Figure 2. When MBR is combined with RO, the total effluent can be recycled and utilized. At KIE, the MBR plus RO process has been in operation for eight years and reduces manufacturing water consumption by 70% and decreases annual water costs by $50,000. This presentation will detail the industrial wastewater treatment and subsequent water reuse at the KIE plant in Jefferson, GA.