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Wastewater Treatment Options: Traditional Septic | AWTS | Wet Composting 
| Sand Filtration | Electro-Flocculation |

Australia is the driest inhabited continent on the Earth. Fresh drinking water is one of our most scarce and valuable resources yet we carelessly waste it everyday!  We are literally flushing drinking water down the toilet! On-site wastewater re-use provides numerous opportunities to reduce water use within the home and help reclaim and treat wastewater for low health risk uses like watering the garden, flushing the toilet and washing the car. At present, potable (drinkable) water is used for practically everything in the house and garden including flushing the toilet! There are two types of wastewater created in a home, each of which can be treated and used in various ways – Blackwater and Greywater. Blackwater is water that has been mixed with waste from the toilet. Blackwater requires biological or chemical treatment and disinfection before re-use. Blackwater should only be re-used outdoors. Greywater is wastewater from non-toilet plumbing fixtures such as showers, basins and taps. Depending on its use, greywater can require less treatment than blackwater and generally contains fewer pathogens. Treated greywater can be re-used indoors for toilet flushing and clothes washing, both of which are significant consumers of water. Greywater can also be used for garden watering. The average Australian home produces about 113 litres of greywater per day. GREYWATER LITRES/PERSON/DAY Shower 56 Hand Basin 6 Kitchen tap 12 Dishwasher 5 Laundry tap 7 Washing Machine 27 Total - Greywater 113 Wastewater re-use opportunities vary according to where you live. Urban households typically have a connection to a centralised, or reticulated, sewage system, whereas rural households manage their wastewater on-site. The regulations concerning the treatment and re-use of wastewater vary according to your location. You need to check with your local council or state health authority for advice on the regulations in your area. In some States it is illegal to re-use wastewater in urban areas. Wastewater can be used to flush toilets, water gardens and even to wash clothes. By using wastewater as a resource rather than a waste product you can: Reduce water bills Use less water resources Cut down the amount of pollution going into our waterways Help save money on new infrastructure for water provision and wastewater treatment. Wastewater re-use decreases effluent volumes, reducing the stress on existing centralised wastewater disposal systems, which will work better and last longer. There are two types of wastewater created in a home, each of which can be treated and used in various ways. Wastewater Treatment Systems There are a growing range of on-site wastewater treatment systems available today including the traditional Septic Tank system along with newer treatment systems such as Aerobic Wastewater Treatment Systems (AWTS), Wet Composting Systems, Sand Filtration Systems and Electro-flocculation Systems. 1) Traditional Septic Systems - Septic tanks have been used in un-sewered areas for many years as the most suitable form of primary treatment of sewage. The septic tank is an underground watertight tank generally constructed of concrete or plastic which is usually divided into at least two compartments. The tank receives all sewage and separates the solid portion of the waste from the liquid portion. The liquid portion (effluent) passes out of the tank after approximately 24 hours. The tank performs three functions:  It acts as a settlement chamber for solid materials  It allows some bacterial breakdown of waste materials to occur  It acts as a storage chamber for undigested solid materials which must be removed periodically (usually every 4 years) These types of systems have become unpopular in recent years to to a number of problems that can arise from their use and poor maintenance including:  Sludge accumulating in the tank filling household pipes may become filled with sewage and clogging of the subsoil soil trench system solids.  Effluent rising to the surface posing a risk to public health, particularly to children playing in the vicinity.   Unpleasant smells emanating from the system.    A breeding ground for mosquitoes   After a number of years of use, some soakage systems may fail and require replacement. 2) Aerobic Wastewater Treatment Systems (AWTS) An aerobic wastewater treatment unit is designed to treat septic tank effluent to a level suitable for surface irrigation within the site. The unit may incorporate a septic tank or it may be separate. Following primary treatment in the septic tank, the effluent is treated by a process of aeration, settling and disinfection and then pumped to a dedicated irrigation area as reclaimed water. Aerobic wastewater treatment systems have a series of treatment processes such as aeration followed by clarification to breakdown and treat the wastewater, which is then disinfected, usually by chlorine, before pumping the treated effluent over the land. These types of systems are prone to similar problems associated with septic systems and are becoming less favoured than wets composting, sand filtration or electro-flocculation systems (see below). 3) Wet Composting Systems Wet composting systems involve a series of filtration membranes or layers that separate out the solids from the liquids in common household wastewater. The water is then treated and made available for re-use (commonly for garden irrigation, laundry or toilet use) or fed into sub-surface absorption trenches. The solids are generally composted, commonly using worms. This compost can then use extracted and used in the garden. These systems also allow the composting of other household organic wastes (kitchen and green waste). The key benefits of a wet composting system include: §  Can accept all wastes including grey water §  Can accept kitchen and food wastes § Option to have flush or no flush toilets - potential to save water §   Reuse of resources §   Reduces pollutant load §   No sludge build up in tanks and no periodic sludge removal §   Periodic removal and below ground burial of compost §   Flexibility with the use of pumps - application area upslope if required Costs Several variations on this type of system exist including the one above that directs the solid wastes into a vegetation cell that provides nutrients for a medium to large tree. 4) Sand Filtration Systems Sand filtration systems generally combine a septic system with an effluent filter consisting of sand beds located below the ground that absorb and treat the contaminants borne in the wastewater. Natural sand filtration systems have the ability to treat wastewater to a very high standard with extremely low maintenance. The benefits of sand filter systems include: §   Only require servicing once a year §   Save up to 80% on electrical costs §   No Air Blowers required §   In most installations only one small pump is required §   No chlorine disinfection involved §   If your site allows, no electricity is needed 5) Electro-flocculation Systems Electro-flocculation (see image below) is a technique involving the electrolytic addition of coagulating metal ions directly from sacrificial electrodes. These ions coagulate with pollutants in the water, in a similar manner to the addition of coagulating chemicals such as alum and ferric chloride, and allow the easier removal of the pollutants. In electro-flocculation, the pollutants are removed by the bubbles which are generated during the process, capturing the coagulated pollutants and floating to the surface. This can be a highly effective treatment method, removing in excess of 98% of the pollutants from a single stage process. Whilst these types of systems are very effective, they tend to have a number of draw-backs including: §   Higher energy use than other systems to power the pumps and the electrolysis process §   Produces a contaminated sludge containing metal corrosion that must be disposed via landfill (solids disposal becomes more expensive that  other systems like wet composting) §   Solid wastes cannot be recycled = loss of valuable nutrients Recommended Solution for On-Site Wastewater Treatment – Wet Composting Whilst the quality of treated water produced by most systems are exceptionally high (almost to drinking quality, portable water quality in several systems), wet composting systems provide the best outcomes particularly from an environmental end-point (quality of solid wastes produced) and their cost-effectiveness. The two major suppliers of Wet Composting solutions in Australia include Aqua Clarus and Biolytix. There are a range of system sizes available for small to very large households with up to 10 people. How Much Do These Systems Cost? The cost of these systems vary widely and the final installed cost is dependent upon a number of factors including: Size of system required – affected by how many people in your home What you want to do with the treated water (just garden use, use for toilet or laundry)  Ease of access to your property  Type of soil on your property     How much excavation is required As a guide, you will need to be able to spend between $8,000 to $12,000 to install a wet composting on-site wastewater treatment system. As yet, there are no Government rebates in place for the installation of an on-site wastewater treatment system. Top of page

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