Designing a Latex Effluent Treatment System Using Acid Coagulation Rubber Recovery Tank in Series with a Constructed Wetland

Abstract

Agro industries are at the center of Cameroons economy and the Cameroon Development Corporation (CDC) is the country’s largest agro producer of natural rubber which cultivates and transforms latex and field coagula into industrial grade materials. An average of 6800 tonnes of rubber is produced at the Tiko factory .This generates heavy quantity of effluent been channeled directly to the surrounding waters, constantly polluting it and affecting the surrounding population, company’s image and the ecosystem thus violates Cameroon and ISO 14001 standards. Causing losses of unrecovered rubber, extra charges, sanctions on the company and inability to obtain ISO14001 certification. Therefore it is necessary to design a rubber recovery and effluent treatment system to reduce the damages caused by this untreated effluent. In other to do so we analyzed the existing state, we characterized the waste water and designed a new system taking In to consideration key design constraints like high rubber recovery , use of existing structures onsite , zero energy needed and system efficiency. After analysis of the present state, we recorded the effluent characteristics of, flow rate of 22.2m³/day, TSS of 1031.4 mg/l, BOD₅ 1080 mg/l which are extremely higher than standards. Thus using a formic acid coagulation tank as primary treatment in series with a constructed wetlands as a biological treatment will ¶efficiently remove suspended solid, BOD, COD, phosphorous and, especially to ensure total nitrogen removal. By evaluating the formic acid coagulation we recorded 80- 85% rubber recovery, thus a reduction in turbidity, also we sized a horizontal flow constructed wetland using Echinochloa Pyramidalis to remove the high organic load. 2 parallel wetlands of  area of 2*293.3 m² , dimension (45.3 x 6.5 x 0.6)m , retention time of 1 day , bed porosity of 0.3 made up of fine gravels-sand filter bed with 9 plants per m² of  Echinochloa Pyramidalis, for a projected final discharge effluent of TSS<30mg/l, BOD₅< 50mg/l. Finally we design using Microsoft Visio and solid works to represent a 3 dimensional view. The use of this design in NR agro industries will recover more of its rubber lost in the effluent and treated effluent is in conformity with ISO 14001 standards thus avoiding all the charges link to pollution and improve its company image.