Existing trickling filter WWTP at the Tamale Community Health School
The project team field visit to the project area in Tamale with other partners led by Gert de Bruijne of Daily Business focused on outlining the technical and social feasibility of the SSN project and the availability (locally) of material resources required in the construction process of the project. The inception mission conducted field evaluation of the project community to assess the topography of the terrain and housing structures as well as settlement pattern of the area identify possible bottlenecks for a solid free sewer network and a wastewater treatment facility which are key components of the SSN project.
Existing Treatment Facility
Shortly before planning the project inception, an existing small waste water treatment plant situated at the Community Health Nurses School, a public health training institution located within the Salamba/Sakasaka vicinity had been visited by PerfSan Ltd on routine project area assessment. The school is located next to the original site planned for WWTP location. The team realized that the existing poor functioning of the existing treatment plant at the school could present a win-win opportunity situation for the project. In this case, consideration has been the “renovation” or “replacement” of the malfunctioning treatment plant in other for it to be able to serve the school again, as well as the neighbouring communities. Base on this, we concluded that in built-up settlements and public facilities places such as schools, hospitals and industrial areas; also private companies and institutions should always be carefully assessed as they are often fenced and protected areas and therefore good locations to build waste treatment facilities for the benefit of the owners of the property and adjourning human settlement (housing) communities.
Owing to this, a PP partnership approach and arrangement is obvious. The project partners therefore were eager to conduct a field surveillance at the school to explore the options in detail to identify the common benefits of the stakeholders. We were welcomed by the principal of the school and her team during the weekend and secured their acceptance for the use of the treatment facility as part of the project.
The treatment facility which was designed and constructed to serve about 500 students comprises a sedimentation tank and a 4.0 meter deep basin in which a trickling filter had been built. An automatic electric pump is installed to allow for regular pumping to discharge treated waste water into a open storm drain. The plant is experiencing malfunctioning in some of the various components as the construction does not allow for easy O&M.
As the Community Health school is situated next to the land that was originally identified for the construction of a WWTP the existing wastewater treatment plant offers an interesting opportunity to link the intents of the school and the neighbouring community of sakasaka/salamba. The principal of the school, Ms Comfort facilitated our first meeting with the Regional Director of the Ghana Health Service in Tamale. Dr. Jacob Yakubu Mahama and the approval was immediately given for the project to consider any alternations “renovate” or “rebuild” the waste water treatment plant of the school and extend its function to the residents of Salamba and Sakasaka. Based on this approval an agreement has been reached between the project applicants (PerfSan Ltd and Daily Business) together with Tamale Metropolitan Assembly (TaMA) and the Community Health School to integrate and connect the sewerage network from the Sakasaka/Salamba community onto the WWTP.
The New (proposed) WWTP design option
The project has decided to convert the basin (4.0m) of the existing trickling filter into an Anaerobic Baffle Reactor (ABR) taking into consideration;
1. The use of the optimal depth (4.0m) available at the treatment plant, therefore the basin will be closed using sailcloth to allow for anearobic digestion and prevent malodour;
2. The H2S and CH4 gasses will be directed through a pipe to compost filters;
3. Heating the influent and /or effluent to improve the destruction of pathogens by transporting the influent and effluent through black pipes to rearch temperatures above 55°C;
4. We consider (if budget allows) a pilot small sun collector device to reach high waste water temperatures.
The current sedimentation tank will be improved upon to function as the first baffle of the ABR, and followed by a two parallel rows of compartments. The proposed parallel design of the ABR will allow for easy O&M without the need to stop the entire WWT process. The depth of the compartments beyond the regular 2.0 meter depth may result in better treatment, but that is left to be seen when it has been tested.
However, because the existing structure allows a deeper than usual depth without additional cost the project has decided to consider the situation for research purposes.
The WWTP will be regularly desludged by a conventional vacuum truck for which a simple access road would be built.