ClearTech, launched this week, has taken the dairy industry’s two biggest issues, effluent losses and water consumption and dealt with both through a combination of simple water purification principles, managed by a computerised controller.
ClearTech puts a coagulant into the effluent when a farm dairy yard is hosed down. It causes the effluent particles to cluster together and sink, leaving most of the water clear and usable.
Ravensdown effluent technology manager Jamie Thompson said there are challenges to getting effluent to clot given the variable pH, turbidity and content of the waste on any given day.
“That requires a flexible coagulant. In this case we have used ferric sulphate, commonly used for purifying drinking water. It puts a positive charge through the particles, causing them to flock together.”
But the true smarts for the ClearTech system lie in the Programmable Logic Controller (PLC), a type of industrial computer that contains algorithms for constantly assessing the state of the effluent stream and adjusts the amount of ferric sulphate released depending on parameters like temperature and turbidity.
“The trick is not to have too much coagulant introduced or you will just have particles separating because they are over-charged, carrying too much of a positive charge.”
The algorithms were developed over three years research by Lincoln University soil professor Keith Cameron and his colleague Professor Hong Di.
“These algorithms operate around very tight parameters and are at the heart of what makes this concept work consistently.”
The coagulant separation process is claimed to kill up to 99% of micro-organisms including E coli and reduce odour.
Thompson said a key focus for researchers and Ravensdown has been to develop a system that can be affordably retrofitted to a farm’s existing effluent system.
“You would typically have a 20,000 litre clarification tank installed after the system’s sump, where the coagulant is injected. Once the effluent has settled two-thirds of that clear water can be re-used for washing the yard down and the other third will contain the effluent, taking it to the pond for storage.”
Thompson said the key benefits are twofold.
“You then only need about a third of the storage area for your effluent while your water use will reduce significantly.
“By our calculations if every dairy farm in New Zealand had one of these systems the industry would be saving 42 billion litres of fresh water a year, about 17,000 Olympic-sized swimming pools.”
Research by Waikato University master’s student Tom Macdonald found in 2014 that on average farmers in that region had invested just over $1 a kilogram of milksolids in dairy effluent management systems in the past five years.
Indications are a further tightening since then in environmental standards demanded further investment.
Thompson said effluent pond upgrading and upsizing is a significant portion of the funds invested, with environmental spending accounting for 70% of total farm environmental spend.
“What this technology does is it significantly reduces the size of the pond required.”
While reluctant to put a price on the installation and running costs for the ClearTech system he said affordability was a key part of the project’s original brief.
“We have been showing this system to key industry stakeholders prior to launch and in all cases they have said this is exactly what the industry needs right now. It has been very, very encouraging feedback,” Thompson said.
Dairy Holdings chief executive Colin Glass said “This technology has the potential to transform the use of water in dairy operations and provides another tool for reducing nitrogen losses.”
The system is expected to be available for farmers later this year.
