Design and sizing of a brewery wastewater treatment system in Douala, Cameroon: a technological solution for the protection of the environment in Sub-Saharan Africa

摘要

This article aims to design a wastewater treatment plant (WWTP) for brewery industry located in Douala-Cameroon (Central Africa) that can be applicable in Sub-Saharan Africa in similar affinity pattern. More specifically, to characterise wastewater, operate a technical choice for wastewater treatment and to design a WWTP infrastructures. Data were obtained through measurements of the flow of wastewater by the volumetric method and water quality data were collected at the outlet point of the brewery company by sampling and laboratory analysis using standard methods. The main results show that the Chemical Oxygen Demand-COD (1082 mg/l), the Biochemical Oxygen Demand-BOD_5 (466 mg/l), the amount of faecal coliforms and of total coliforms (respectively, 0.99 and 6.77 million UFC/100 ml) norms in wastewater are above the Cameroonians and World Health Organisation (WHO) standards for waste disposal. The treatment technology "bacterial bed" was considered the most suitable to treat the brewery wastewater. It has a rate of flow estimated at 2700 m~3 per day. The WWTP has seven components, including a sieve (meshes 0.5 cm), a deoiler (ventilation power 3400 Watts), a lamellate decanter (volume 1165 m~3), a bacterial bed (cloisonyl, height 2.5 m and surface 676 m~2), a second lamellate decanter with processing of calco-carbonic balance (Consumption CO_2 81.07 Nm~3, diameter 25 m), a bio-digester, a basin of disinfection (surface 338 m~2, rate of processing 0.65 g/m~3, flow of injection 121/h). The construction of this WWTP will enable the improvement of environmental protection around the company and hence, the city of Douala in Sub-Saharan Africa.