Facts On Your AWTS

Aerated Wastewater Treatment Systems (AWTS)

What is an AWTS?

How does an AWTS work?

Regulations and recommendations

Maintaining your AWTS

Conserve water

Minimise the amount of solids deposited into your AWTS

Do not put chemicals down the drain

Don't

Warning sign of AWTS failure

Help protect your health and the environment

Aerated Wastewater Treatment Systems (AWTS)

In unsewered areas, the proper treatment and utilisation of household wastewater on-site is critical in preserving the health of the public and the environment. AWTS's have been developed as a way of achieving this.

What is an AWTS?

An AWTS does the job normally handled by a large Sewage Treatment Plant. Instead of occupying large tracts of public land, it is a purpose built system used for the treatment of sewerage and liquid wastes from a single household or multiple dwellings.

It consists of a series of treatment chambers combined with an irrigation system. An AWTS enables people living in unsewered areas to treat and utilise their wastewater.

How does an AWTS work?

All water borne wastes from kitchen, laundry, bathrooms and toilets are treated in stages in several separate chambers. The first chamber is similar to a conventional septic tank. The wastewater enters the chamber where in the absence of oxygen (anaerobic) bacteria which thrive in these conditions reduce the toxicity of wastes. The solids settle to the bottom and are retained in the tank forming a sludge layer. Scum collects at the top, and the partially treated wastewater flows into a second chamber.

Here oxygen is introduced to the mixture. The oxygen, provided from a compact air pump (blower), together with nutrient present in the wastes, promotes the breeding of aerobic bacteria.

A third chamber allows clarification through the settling of solids, which are returned for further treatment to either the septic chamber or to the aeration chamber where it goes right back to work as activated material to assist in the treatment process.

The clarified effluent is disinfected in another chamber (usually by chlorinating). From here a pump periodically sprays it into designated irrigation areas in the garden.

Bacteria in the first chamber break down the solid matter in the sludge and scum layers. Materials that cannot be fully broken down gradually build up in the chamber and must be pumped out periodically.

Regulations and recommendations

Local councils are primarily responsible for approving the smaller, domestic AWTS's in their area. The Environmental Protection Authority (EPA) approves larger units, whilst the NSW Department of Health determines the design and structural requirements for all AWTS's.

At present AWTS's need to be serviced quarterly by an approved service provider at a cost to the owner. Local councils should also maintain a register of the servicing of each system within their area.

AWTS's should be fitted with an alarm having visual and audible components to indicate mechanical and electrical equipment malfunctions.

Maintaining your AWTS

The effectiveness of an AWTS (aerated wastewater treatment system) will in part depend on how it is used & maintained. The following is a guide on good maintenance procedures that you should follow.

Conserve water

Water conservation is the single most beneficial action you can take to protect your AWTS (not to mention the environment as a whole!). Your AWTS was designed to handle a certain daily flow of wastewater. Keeping your household water usage well below your AWTS's daily design flow is a simple but powerful way to help your AWTS produce good quality effluent. Consistently exceeding the daily design flow impacts on both the volume and quality of effluent that enters your designated irrigation area. High flows disrupt the solids settling process and push out partially treated effluent. Water overuse is one of the leading causes of an AWTS failure.

The following are specific water conservation measures you can easily implement in your home:

Fix leaky taps and toilets. A leaky toilet could overload your AWTS with hundreds of litres of wasted water per day
Take steps to minimise your water usage. Limit showers to 5 minutes, fill bathtubs half full and remember not to let the tap run when you're shaving, brushing your teeth or washing dishes, vegetables or your hands etc.
Retrofit your showerhead with a water saving (low flow) device
Retrofit your toilet with a water saving device, or if replacing your toilet system use a low volume dual flush system
Do laundry only when you have a full load and try to spread laundry over the week rather than doing all your laundry at once. If you're in the market for a new washing machine consider a front-loading machine rather than a top loading one
If you use a dishwasher, run it only when full.

Minimise the amount of solids deposited into your AWTS

Your AWTS is designed to handle human waste, toilet paper and water from your basic household appliances. Overloading your AWTS with solids will mean your require a solids removal (pump-out) more often. It can also cause AWTS failure.

The following tips address the most common mistakes made when it comes to solids disposal and your AWTS:

Avoid using an In-Sink-Erator. In-Sink-Erator garbage disposal units significantly increase the amount of solids entering your AWTS, making your AWTS's sludge accumulate more rapidly. This means more frequent solids removal (pump-outs) will be required. An In-Sink-Erator garbage disposal unit can reduce the time between pump outs by 1-2 years. Consider creating a compost heap in your garden to get rid of food scraps
Avoid disposing of cooking oils or grease down the drain. Rather, pour them into containers, let the oil/grease harden and throw them away in the garbage
Don't flush nappies, paper towel, facial tissues, feminine hygiene products, cigarettes butts or other non-biodegradable items down your toilet
Coffee grounds, egg shells, large amounts of hair and kitty litter are other common household items that should be thrown away in the garbage and not into your AWTS.

Do not put chemicals down your drain

Your AWTS is its own ecosystem adding chemicals including some household cleaners, toxic substances like paint, solvents and pesticides disrupts this ecosystem, killing off the bacteria that recycles your wastewater. Because chemicals can pass right through your system, they can damage soil structure and contaminate groundwater in nearby lakes and rivers.

The following chemical usage tips will help you help your AWTS and the surrounding environment:

The most important rule with household cleaners is to use them as sparingly as possible. Try to avoid the use of household cleaners such as bleach and anti-bacterial detergents. While most AWTS's can accommodate small amounts of such cleaners, large doses will destroy critical bacteria populations in your AWTS
If you have a clogged drain, use boiling water or a drain snake rather than caustic drain cleaners
Use low-phosphate detergents to avoid environmental damage. Releasing phosphates into your local environment can spawn destructive algal blooms, (including blue green algae) in the lakes and rivers nearby your house
Use anti-bacterial soaps and bathroom cleaners sparingly, used in excess, these can destroy bacterial populations in your AWTS
Don't flush unused medications down the drain. Here again, such substances have an adverse effect on your AWTS's bacteria
Don't discharge pool backwash into your AWTS. Not only will this increase your water load, chlorides and salts in the discharge will harm your AWTS's bacteria
Biological septic system "additives" (e.g., bacteria, enzymes) sold to "jump-start" your system are unnecessary
Proper care and maintenance (including regular service), not septic additives, is the only sure way to promote a healthy AWTS
Never dispose of toxic chemicals in your AWTS.

These include (but are not limited to) the following:

Paint, paint thinner and paint strippers
Solvents
Pesticides/herbicides
Fertilizers
Motor oil, petrol, antifreeze, brake fluid and other automotive fluids
Photographic chemicals

Have your AWTS inspected and serviced four times per year by an accredited service provider. Assessment should be applicable to the system design
Have your system service include assessment of sludge levels in all tanks, and system performance
Have your disinfection chamber inspected tested and cleaned quarterly to ensure correct disinfection levels
Keep a record of services, pump outs and other maintenance
Learn the location and layout of your AWTS and designated irrigation areas.

Don't

Don't switch off power to the AWTS, even if you are going on holidays.

Warning signs of AWTS failure

You can look out for a few warning signs that signal to you that there are troubles with your AWTS. Ensure that these problems are attended to immediately to protect your health and the environment.

Look out for the following warning signs:

Water that drains too slowly
Drain pipes that gurgle or make noises when air bubbles are forced back through the system
Sewage smells this indicates a serious problem
Water backing up into your sink which may indicate that your system is already failing
Wastewater pooling over the designates land application areas
Excess noise from the blower or pumping equipment
Poor vegetation growth in designated irrigated areas.

Odour problems from a vent on the AWTS can be a result of slow or inadequate breakdown of solids. Call your service contractor to rectify the system.

Help protect your health and the environment

Poorly maintained AWTS's are a serious source of water pollution and may present health risks, odours and attract vermin and insects.

By looking after your AWTS you can do your part in helping to protect the environment and the health of you and your family.