公害ジャーナル

Conceptual Design of a Decentralized Wastewater Treatment System for the Bamenda Regional Hospital, Cameroon

Abstract

Patamaken Aneck Simon Ndibnuh, David NY and Ilorme F

The Bamenda Regional Hospital, like most hospitals in Cameroon, lacks an appropriate wastewater treatment system. The main objective of this work was to evaluate the state of the existing sanitation infrastructures in the Bamenda Regional Hospital and design a decentralized wastewater treatment system for the Hospital. The research methodology involved pre-research preparations, field data collection via semi-direct interviews with officials of the hospital, field observations and data analysis. Results obtained from semi-direct interviews and field observations revealed that the existing sanitation infrastructures in the hospital are inappropriate for the treatment of the hospital’s wastewaters due to their deteriorating state and poor design. We therefore designed in this paper a decentralized wastewater treatment system made up of a sewer network constituted of 12 main PVC pipes (S1, S2, S3, S4, S5, S6, S7, S8, PS, PS1, PS2 and PS3) and four treatment units: a settling tank (volume=13.25 m3, area=3.68 m2, depth=3.60 m, width=1.84 m and length=2.00 m); two 6-chambered anaerobic baffled reactors placed in series (each having a working volume of 317.95 m3, compartment up-flow area of 22.08 m2, total compartment area of 29.44 m2, reactor depth of 3.00 m, reactor width of 7.28 m and a reactor length of 14.56 m) ; two 3-chambered anaerobic filters placed in series (each having volume of filter of 66.24 m3, volume of packed bed of 41.4 m3, area of 27.6 m2, depth of 2.40 m, width of 5.25 m and a length of 5.25 m); and a horizontal planted gravel bed (with a cross-sectional area of 8.83 m2, total length of 7.00 m, width of 1.26 m, height of 1.5 m and 36 plants). A pump with an effective power of 0.03 KW was also designed. The choice of the system proposed in this work was governed by the fact that: the cost of construction, operation and maintenance of the different treatment units is relatively low compared to other technologies; the construction materials are locally available; the system does not require large area since the units are constructed underground; the system energy requirement is very low or almost zero; reports from researchers reveal that the different units combined in the chosen system have individually shown good treatment efficiencies.