Integration of sanitation into natural cycles: A new concept for cities

Water closets and flushing sewerage systems have first been installed in very humid countries with small population densities. Even with the best economically feasible wastewater treatment the problem created by mixing faeces with a lot of water can not be compensated. I Jew technologies applied in future should no longer mix the human food cycle with the water cycle. This requires toilet-systems with no or very low water consumption. Highly concentrated organic material may be composted or treated in anaerobic reactors. Composted or digested sludge fron households only will be fairly unpolluted and can be used as the best possible fertiliser for agriculture. By these technologies the inorganic substances taken from the soil by the farmers can be returned in about the appropriate quality and quantity. There are also positive effects on the energy balance with savings by avoided aerobic treatment and avoided production of artificial fertilisers. Another advantage is the option to treat a good portion of organic solid waste from households in the same systems. A pilot project for a new settlement of about 300 inhabitants in Lubeck, Germany shall demonstrate the feasibility of a new integrated system with vacuum toilets and pipes for semi-centralised anaerobic treatment. Greywater will be treated in decentralised biofilm systems. Stormwater is collected, retained and infiltrated in a through and drain trench system. This way no centralised sewerage system will be necessary for this settlement.