Long-term sewage treatment for remote applications can be provided by instal- ling packaged sewage treatment plants that are easy to operate and robust, says Irish plant manufacturer Bannow Exports MD Ted O’Morchoe.
The ease of operation of packaged sewage treatment plants is critical for their common applications in remote places, such as island the resorts in the Seychelles and the Maldives, as well as in rural areas, such as the demonstration plant at Olwazini, in South Africa’s Cradle of Humankind, in Gauteng.
The modular plants enable easy expansion of existing systems to meet the scale of treatment demand.
“Packaged plants should be prefabricated, so that quality control is done in the factory and does not depend on work on site, where installation must be quick and simple.”
Bannow Exports, of which Bannow Africa is its local subsidiary, reports that its Blivet packaged sewage treatment plant, a hybrid of rotating biological contactor and activated sludge technologies, removes ammonia, nitrates and nitrites, phosphorus and nut- rients, with the option to design the system to enable effluent to be used for irrigation of crops.
Disinfection, should it be required, is done using ultraviolet disinfection or liquid or tablet chlorine dosing matched to the flow rate. The Blivet plants can also be monitored remotely.
“As soon as people get water into their homes, they will begin to produce sewage. We should use packaged sewage treatment plants to contain pollution before it becomes a problem.
“The plant can be applied as a short-term solution to bolster overloaded municipal sewage treatment plants, or as a sustainable, long-term solution in areas that need treatment capacity but are not connected to sewer- age pipes, or in remote locations where it is not economically viable to install large- scale municipal treatment plants,” he explains.
“Further, a single plant can be installed for up to 100 houses or can be deployed in series and in parallel to provide treatment for larger populations,” notes O’Morchoe.
The effluent flows into a primary settlement tank and then into the heart of the plant, which is its Aerotor rotating biological drum. As the drum rotates it lifts the effluent into its channels, effectively aerating it to promote bacteria and biomass growth, which absorb the nutrients.
Further, the system has low power consump-tion, owing to its design that uses the rotation of the drum to aerate the effluent, and can also be designed to use solar power sources.
“The Blivet has low operation requirements and naturally adjusts to changes in flow rate, with bacteria growth proportional to sewage inflows.”
Meanwhile, the system has a life span of 20 years in normal applications and is sustainable owing to its low requirements for electricity and maintenance.
A project in Ireland saw the company installing 22 Blivet units to provide temporary treatment for a housing development near Dublin, until the municipality could build a formal sewage treatment plant within five years. The Blivet plants have been in operation at these sites for almost ten years and the municipal plant will only be completed this year, he notes.C
ommissioning such a plant takes a few months, and the plants are sustainable and an effective way for corporate companies or nongovernmental charities to boost local communities, he adds.
Bannow Africa provides standalone units and fully engineered solutions that can include more rigorous treatment, such as disinfection, depending on the application. The management of sludge from the plants is similar to other biological treatment systems, and the plant has three months of insludge storage. Sludge drying beds can be included to reduce the amount of sludge in remote locations, he concludes.