Wednesday, May 03, 2006

Sewage farms

I spent most of today with environmental studies students looking at a fascinating environmental facility - the Western Treatment Plant at Werribee. This is a sewage farm, located south-west of Melbourne, and covering more than 11,000 hectares. It treats about 52% of Melbourne's sewage in a way mimicking the operation of a natural wetland. Sewage passes through a long series of lagoons, where along with natural decomposition it is aerated to decompose it into methane and sludge. The methane is collected and burnt to generate electricity which provides 80% of power on the plant. It is a cost-efficient and environmentally-effective operation.

The plant has recently been subjected to a $160 million environmental upgrade to improve the health of Port Phillip Bay into which it pours treated effluent. This upgrade will reduce nitrogen flowing to the bay and increase the supply of high quality recycled water that can be used for agricultural, horticultural and many other applications. This water is sold to off-plant agricultural and industrial concerns. Another effect of the upgrade is that much more of the plant can be devoted to conservation activities and agriculture rather than sewage treatment.

In addition, an independent business unit of Melbourne Water, manages the grazing of 15,000 cattle and 40,000 sheep on over 8500 hectares of land at the plant. Much of this area simultaneously serves as a biodiversity conservation resource.

In biodiversity conservation terms, the Western Treatment Plant is one of the two most important wetlands in Australia – the other being Kakadu. In 1982 Lake Borrie (you can view by webcam) and much of the surrounding wetland at the plant was nominated as a wetland of international significance under the Ramsar Convention. It has recorded over 270 species of birds which is one-third of Australia’s avifauna. It regularly supports over 20,000 waterfowl and several species of waders and ducks. Migratory wading birds fly to the plant from Siberia to escape the northern winter – some have a 25,000 km journey. In recent weeks Orange-bellied parrots have been observed at the plant. Over the years I have seen them several times here.

This is an intriguing facility. It combines an urgent social priority – disposing of sewage – with commercial agricultural concerns and, at the same time, delivers an outstanding biodiversity conservation outcome.

Further useful information on the Western Treatment plant is provided at the Melbourne Water Website here. The 2003 Environment Improvement Plan is here. A virtual tour of the plant is Western Treatment Plant Explorer although taking an actual tour is better. If you are interested in practical solutions to significant environmental issues and are interested in avifauna this is an important place to visit.


conrad said...

I am impressed by it too. After I lived in Sydney for 4 years, and Hong Kong for a few more (and worked in mainland China a bit), I am now not just impressed by it, I am amazed. Its one of the great things about Melbourne that no-one thinks about, and is one of the reasons the bay is so clean for such a big city. I think, like most types of pollution, people don't think about it simply because it isn't there to think about.

It would be great for everyone if they could set up similar things in places like mainland China, where they have lots of space, but terrible sewage problems. Sydneysiders might think about it too, instead of trying to build bigger pipes out to sea (the fools).

Do you know how much these things cost to set-up excluding land ?

hc said...

The main cost is the land cost. But the land used with the newer technology is limited and it also provides direct economic benefits in terms of argicultural production and a superb biodiversity resource. It certainly outperforms Sydney which is still pouring untreated sewage directly into the ocean.

And water quality in OPort Phillip Bay (even before the recent upgrade of the plant) has been improving.