There is a variety of alternative on-site treatment systems that can also be used for domestic effluent. Three examples are:
These systems consist of a separate vault that collects the toilet waste only. Some composting toilets also collect the urine separately prior to it entering the composting pit. Generally, very little liquid effluent is produced and the solid waste is composted to produce a safer, less offensive final product. To get the best results from these systems, a greater amount of regular attention is required than with other treatment systems. The resulting compost will still need to be buried for up to a year to make it safe for human contact, particularly if it is to be used as fertiliser in a vegetable garden. Your District Council Health Inspector should be able to provide more detail on what is deemed safe.
If you have a composting toilet, the grey water (water from showers, kitchen and laundry) from your house also needs to be properly treated and disposed of on your property. The grey water system will normally be similar to a standard septic tank system, which allows for the settlement and collection of solids from the grey water. The liquid effluent produced from the composting material and, if your composting toilet does so, the collected urine also requires proper treatment and disposal. The most cost effective method will normally be through the grey water system.
Also known as Biolytic filtrations, these treatment systems consist of a chamber in which both liquid and solid effluent is passed over a bed of organic matter containing earthworms. The effluent filters down through the organic layer leaving the bulk of the solid material behind to be broken down into compost by bacteria and earthworms. The earthworms also assist with the aeration of the organic waste, which reduces any smell. Any remaining liquid effluent is collected and disposed of in a similar manner to effluent from a septic tank.
These systems require more maintenance than standard septic tank systems and the manufacturer / supplier of your system should provide a maintenance schedule that must be followed. Most of these systems are not designed to treat all the liquid effluent from a dwelling and you will also require a separate grey water system.
The recommendations in this booklet regarding septic tank treatment and disposal systems also apply to grey water systems.
Sand and Textile Filter systems
These types of systems provide a greater level of effluent treatment than an AWTS and are also considered suitable for effectively handling shock loading. This additional treatment is achieved by small amounts of effluent being passed through the filter material at regular intervals.
These systems normally have mechanical pumps that require a continuous power supply, and the treated effluent is usually disposed of in the same manner as effluent from an AWTS. The mechanical pumps and filter material require regular maintenance, as does the irrigation line, to ensure they are operating correctly. A contract with the manufacturer of your system, or their authorised agent, will be needed to undertake this regular maintenance.