Secondary treated wastewater of latex processing: reusing for irrigation or treatment by membrane filtration

Many technologies have been developed to treat the rubber effluent, but the quality of the treated effluent after the secondary treatment still does not meet the requirements for releasing it back to water bodies. This treated effluent becomes one of the most challenging problems for the Vietnamese rubber industry. Therefore, the present paper studied two applications as a potential solution for this issue. The first one is an advanced technology using membrane ultrafiltration, for a higher quality of the treated effluent that meets the disposal requirements. The second application is a direct reuse of the effluent for agricultural irrigation. For investigation of the effectiveness of the membrane filtration, a small-scale ultrafiltration apparatus with polyacrylonitrile membrane was used to conduct experiments on synthetic wastewater. The obtained results indicate that the membrane significantly reduced the COD concentration of the treated effluent to a level below the limit of 50 mg/L set by the Vietnamese Regulatory for discharge to water bodies. Kinetics of membrane ultrafiltration was also discussed. For the reuse of the treated effluent for irrigation, the effluent must have no negative impact on the groundwater. In order to investigate this aspect, a large-scale penetration test was conducted using a column filled with soil samples collected from rubber plantations in Binh Duong. The column penetration test results show that the irrigated effluent posed no harmful effect on groundwater. All COD, total nitrogen and phosphorous concentrations at a depth higher than groundwater were lower than the discharge limits for treated wastewater to water bodies.