The major advantages of the Rottebehaelter system over other systems such as septic tanks are that it does not deprive agriculture of the valuable nutrients and soil conditioner from human excreta and does not require expensive tanker truck. The system is low-cost and allows reuse of nutrients and soil conditioner in agriculture. Relatively dry and stable retained materials can be obtained in the Rottebehaelter with composting by adding sufficient amount of bark regularly as well as with vermicomposting by adding worms. The latter was more effective to reduce the moisture content and to accelerate the degradation of the retained materials. However, low temperature composting took place which needs more than a year to kill all pathogens specially Ascaris. Vermicomposting, however, is an effective process to sanitise faecal materials. The final product is hygienically safe as the human excreta will be completely converted to vermicastings. The typical analysis of the vermicast of wastewater sludge in Australia revealed that pathogens such as enteric viruses, parasite eggs and bacteria such as E.coli have been reduced to safe levels for use in the garden.

Figure 31: Fresh material (Left) and finished material after 3 months of vermi­com­posting

Compared to composting with adding bark in retained materials, vermicomposting has several benefits. In the Rottebehaelter, moisture content is too high for composting of the retained materials that are structurally poor, whereas this range of moisture content is optimal for worms to work effectively. Structural materials such as bark have to be added for composting. Adding bark regularly and sufficiently is not an easy job.

In a good functioning Rottebehaelter system, solid-liquid separation, dewatering, low temperature composting or vermicomposting can be achieved in one unit. It can be implemented where people use flush toilets. Therefore, the septic tank systems can be replaced by the ecologically and hygienically advantageous Rottebehaelter system for household wastewater treatment. There is no need to construct a new tank, since the existing tank can be modified, if the tank is watertight at least at the bottom where the filtrate is collected. The Rottebehaelter systems are most beneficial when they are integrated in resource management sanitation for rural and peri-urban areas where local post treatment and reuse is possible. This has ecological, economical and hygienic benefits.

It has to be stated that because maintenance is a crucial factor, removal and handling of the retained material has to be improved. In addition, proper procedures of further composting and usage should be established. The loss of water level does make it more appropriate for sites with a good gradient, otherwise an additional pump may be required. Compared to other systems such as septic tanks, there are major advantages.