Researching a perfect effluent system

31 Jan, 2017 02:00 AM
Dardanup dairy farmer Michael Twomey holding shy daughter Nyah, 5, his son Michael, 6, Western Dairy project officer Dan Parnell and environmental engineering student Laura Senge inspecting the effluent system.
Dardanup dairy farmer Michael Twomey holding shy daughter Nyah, 5, his son Michael, 6, Western Dairy project officer Dan Parnell and environmental engineering student Laura Senge inspecting the effluent system.

ACCORDING to Dardanup dairy farmer Michael Twomey there is "no perfect system" for dealing with the effluent generated by 500 cows being milked twice a day.

But Western Dairy project officer Dan Parnell and Murdoch University environmental engineering honours student Laura Senge hope to prove him wrong.

Western Dairy and WA's Department of Water (DoW) have combined to award a scholarship to Ms Senge to design a zero waste discharge - nothing leaves the farm - dairy effluent management system as her honours project.

Her challenge is to create an integrated dairy water supply and effluent system that eliminates soil and water pollution while minimising water demand and maximising outputs such as energy, soil nutrients and fit-for-purpose water recovery.

Her project will be incorporated into the Royalties for Regions-funded DairyCare project Western Dairy and DoW are undertaking to improve catchment water quality under the Regional Estuaries Initiative.

Mr Twomey explained its benefits and shortcomings to Ms Senge and Mr Parnell during a farm visit last week.

A two-pit solids trap system was installed 12 months ago when a new dairy and yards were built on the farm third generation dairy farmer Mr Twomey returned to after 13 years in the mining industry as a surveyor.

The rotary dairy's under-platform area and yards drain into one end of a large concrete pit beside the yards.

A 250,000 kilolitre dam and pump provide water to high pressure wash down cannon which can be directed, if needed, into the effluent pit to break up floating solids.

Plastic plumbing with a low-level entry point picks up liquid from beneath floating solids and links via a t-piece to the adjacent smaller pit which is monitored by high and low-level probes.

An electric pump pushes liquid waste from the second pit through a non-return valve - to retain prime - and out through a buried pipe to a modified centre pivot irrigator in a nearby paddock.

A hose up the centre of the pivot tower and underslung along the pivot arm carries liquid waste to a simple 50 millimetre 'knocker' sprinkler which can be moved along the pivot arm to alter the area of the paddock receiving water from the effluent pit.

"The system works pretty well, but it's not perfect - there is no perfect system," Mr Twomey said.

"I turn the pump on before I start milking and set the irrigator walking, but I can go a couple of days without having to do that.

"We currently use about 10,000 litres of water a day and the pits will hold 22,000 litres.

"Yes, the sprinkler does get blocked occasionally, we've also had to replace the packing (at the base of the pivot tower where the pipe enters) annually and every five to six months get into the (bigger) pit with the tractor and bucket to clean it out.

"At this stage we've just been stockpiling the solids in one area to dry and we'll probably end up spreading it over paddocks."

Ms Senge, who came to Australia from Germany three years ago to study, said she was not put off by a lack of farming experience or the material she was dealing with.

"My engineering work so far has mainly been with water and this (dairy effluent) is just water with a solids content," she said.

"The aim is zero waste with nothing leaving the farm, but I recognise that practicality and economic constraints make it an ambitious target."

Western Dairy regional manager Esther Jones said the project team was seeking expressions of interest from dairy farmers wanting to have their effluent system reviewed.

"Through our DairyCare project, we will be working closely with farmers in the Geographe, Hardy and Leschenault catchments to establish willingness to make a commitment to improved effluent management," Ms Jones said.

"We have funds through the project to undertake 60 reviews - a process that will give a real insight into the opportunities to improve the effectiveness of current systems."

Ms Jones said Ms Senge's scholarship was the first Western Dairy had awarded in the environmental management field.

She said Western Dairy's support included funding Ms Senge to undertake the dairy industry's nationally-recognised effluent design course, while DoW was funding her travel to farms with the project team as she develops her design.

To volunteer for an effluent system review, contact Mr Parnell on or 0467 556 542.

Mal Gill

Mal Gill

is wool and dairy writer for Farm Weekly


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