Transfer and Sewer Discharge Stations

Operators of human-powered or small-scale motorised sludge emptying equipment (see human-powered and motorized emptying and transport) discharge the sludge at a local transfer station rather than illegally dumping it or travelling to discharge it at a remote treatment or disposal site. When the transfer station is full, a vacuum truck empties the contents and takes the sludge to a suitable treatment facility. Municipalities or sewerage authorities may charge for permits to dump at the transfer station to offset the costs of operating and maintaining the facility. 

In urban settings, transfer stations have to be carefully located, otherwise odours could become a nuisance, especially, if they are not well maintained.

Transfer station

A transfer station consists of a parking place for vacuum trucks or sludge carts, a connection point for discharge hoses, and a storage tank. The dumping point should be built low enough to minimize spills when labourers manually empty their sludge carts. Additionally, the transfer station should include a vent, a trash screen to remove large debris (garbage) and a washing facility for vehicles. The holding tank must be well constructed to prevent leaching and/or surface water infiltration.

Sewer discharge stations

A variation is the sewer discharge station (SDS), which is like a transfer station, but is directly connected to a conventional gravity sewer main so that it can be transported to a semi-centralised secondary treatment system. Sludge emptied into the SDS is released into the sewer main either directly or at timed intervals (e.g., by pumping) to optimize the performance of the sewer and of the wastewater treatment plant, and/or reduce peak loads. The station should be well protected and maintained to prevent random dumping into the sewer and to ensure the safety of the users. As for the transfer station (see above), expert design and construction supervising are required.

Transfer stations can be equipped with digital data recording devices to track quantity, input type and origin, as well as collect data about the individuals who dump there. In this way, the operator can collect detailed information and more accurately plan and adapt to differing loads.

The system for issuing permits or charging access fees must be carefully designed so that those who most need the service are not excluded because of high costs, while still generating enough income to sustainably operate and maintain the transfer stations.

Transfer stations have the potential to significantly increase the health of a community by providing an inexpensive, local solution for faecal sludge and septage disposal. By providing a transfer station, independent or small-scale service providers are no longer forced to illegally dump sludge, and homeowners are more motivated to empty their pits. When pits are regularly emptied and illegal dumping is minimized, the overall health of a community can be significantly improved. The location must be carefully chosen to maximize efficiency and minimize odours and problems to nearby residents.

The moderate capital costs may be offset with access permits and the construction and maintenance can create local income. The system for issuing permits or charging access fees must be carefully designed so that those who most need the service are not excluded because of high costs, while still generating enough income to be sustainable and well-maintained. Also the costs for maintenance, observation and operation of the facility must be considered.

Screens must be frequently cleaned to ensure a constant flow and prevent back-ups. Sand, grit and consolidated sludge must also be periodically removed from the holding tank. There should be a well-organized system to empty the transfer station; if the holding tank fills up and overflows, it is no better than an overflowing pit. It is important, that there is a person or organisation responsible who organises the logistic of the facility.

The pad and loading area should be regularly cleaned to minimize odours, flies and other vectors from becoming nuisances. It should be ensured that the sludge from transfer or sewer discharge stations is treated in an appropriate secondary treatment facility (e.g. planted or unplanted drying beds, anaerobic digestion or composting large scale) and not be illegally dumped. Also, the sewers need to be inspected periodically to avoid blockages.