Investigation of the effectiveness of source control sanitation concepts including pre-treatment with Rottebehaelter.

High levels of nutrients recovery can be achieved with source control sanitation--technologies are already available. Separation toilets for example separate urine that can be used in agriculture with some crop restrictions as a fertiliser after about 6 months of storage. The grey water has very low loads of nitrogen and can be treated in different combinations of biological and physical treatment and reused. Faecal matter with flush water from the separation toilet can be discharged into Rottebehaelter (an underground pre-composting tank) that retains solid material and drains liquid to a certain extent. Investigation of Rottebehaelter in the different sites and laboratory experiments showed that retained faecal material still contained a high percentage of water. However, odour was not noticed in those Rottebehaelters that have been examined. One of the major advantages of this system over other forms of pre-treatment as the septic tanks is that it does not deprive agriculture of the valuable nutrients and soil conditioner from human excreta. It has to be stated that maintenance is a crucial factor. As an intermediate result of the intensive research of Rottebehaelter it seems that these systems are rather a way of solids retaining, de-watering and long-term storage before the contents are further treated.

Greywater treatment by constructed wetlands in combination with TiO2-based photocatalytic oxidation for suburban and rural areas without sewer system.

In this study greywater treatment through constructed wetlands and subsequently through TiO2-based photocatalytic oxidation was investigated. Through constructed wetlands treatment the organic substances have been reduced greatly. For further removal of organic substances and pathogens, a TiO2-based photocatalytic oxidation process was used subsequently. The results showed that the treated greywater through constructed wetlands and subsequent through TiO2-based photocatalytic oxidation with short irradiation time (3 hours irradiation time) met the requirements of European bathing water quality easily. Therefore, the greywater treated with the processes combination can directly be reused for non-potable purposes. Moreover, since residual organic substances through TiO2-based photocatalytic oxidation with long irradiation time can be eliminated almost totally, it is also possible that treated greywater is used for groundwater recharge as a drinking water resource.

Pre-treatment of domestic wastewater with pre-composting tanks: evaluation of existing systems.

A relatively new technology called pre-composting tank or Rottebehaelter, retaining solid material and draining water to a certain extent, has been found to be an interesting component of decentralised systems to replace the usual septic tank. Results of the investigation revealed that solid material which has been retained in the pre-composting tanks still contained a high percentage of water. However, there was no odour problem at and near the tanks. The pre-composted materials have to be further composted together with household and garden wastes for a year prior to their use as soil conditioner. The filtrate is further treated in a constructed wetland. One of the major advantages of this system compared to other systems, such as septic tanks, is that it does not deprive agriculture of the valuable nutrients and soil conditioner from human excreta and does not require an expensive tanker truck. It can be the most appropriate system for application in regions where there is a demand for local reuse of the end product. It has to be stated that maintenance is a crucial factor.