Most of the cities in Afghanistan are built without a proper sewage system, for example Kabul is a metropolitan city with only 3% of the houses connected to sewage and treatment plant.
97% of the city does not have sewage systems and treatment plant for wastewater and they only collect the toilet wastewater: in septic tanks (18%), pit latrine/cesspit (65%), and dry toilets (14%).
All other domestic wastewater flows to the open channels which are connected to the river, therefore in dry season the river becomes a sewage channel. Most of the time people illegally drop the sludge from their cesspits, septic tanks and dry toilets to the river and landfill.
What is the best decentralized household wastewater treatment solution? Are there any case studies of cities which have successfully implemented such a solution? All experiences are much appreciated.
Dear Qasem, the best decentralized system for a city like Kabul depends a lot on local conditions, as : -climate -local culture and what is socially accepted -already existing infrastructure -the costs local households can pay -local political and communal organisation -etc. As local conditions are really important, there is not an unique answer.
To start, I would like to recommend you some material done by EAWAG in Switzerland which can help you to design a full system : CLUES : Community-Led Urban Environmental Sanitation Planning http://www.sandec.ch/forschung/sandec/gruppen/SESP/projects_sesp/clues/i... This guidelines are mostly about planning and implementing a sanitation system.
Check out the Integrated Rural Sanitation System (SISAR) in the Brazilian state of Ceará and the ‘condominial sanitation’ system in the city of Recife. You might also want to contact the EU-funded FP7 project DESAFIO which is looking into low tech sanitation solutions and community-led sanitation too.
Published
by Edwin Colyer, Scientia Scripta - Director
Consider the installation of a low pressure sewage system. these system utilize a small pump chamber with a high pressure pump. A common force main, generally less than 3" in size is installed in the ground below frost depth (42" below grade commonly). Individual lines from the septic tank to the common force main is 1.25" or 1.5". the pumps are grinder pumps so the raw sewage is converted to a slurry and pumped to a treatment plant. these systems can be used in flat or hilly terrain. Please contact me if you have any additional questions about these types of systems.
We need to know the total volume of sewage generated? Also why is there consideration for a decentralized system? An answer can be given after studying the topography, land availability and presumably availability of energy. If I presume right Afghanistan is a low per capita energy producer and consumer. If that is the case none of the activated sludge systems will be successful. There will be a need for low energy need technologies to deal with the Wastewater. MAST Technology would be a good way to go about it. If you wish to get more information about MAST please send me an email at advenvtech@gmail.com.