The secret is in the formation of micro-size bubbles; delivered by infusion in ‘bite size’ particles to the latent micro-organisms that are responsible for the degradation of organic impurities (COD/BOD).

AirMix systems are more cost effective to purchase and operate, using a fraction of the horsepower needed by conventional aerators. They are capable of delivering dissolved oxygen to every corner of the pond, dam, lagoon or aeration basin according to your requirements.

AirMix systems stimulate benign organisms to out compete sulphide generating bacteria, (anaerobes), this action greatly assists with the elimination of odours, and usually results in a reduction in acidity.”

www.biosystems.co.za

10 minutes after start-up, intake foot valve is suspended below the white float, it has since been replaced with a still well.

Open ended delivery pipe before submersion – note the remarkably well aerated influent, the white micro air bubbles resembling milk.

2.5 days – the sludge begins breaking up.

Proliferation of oxygenation as micro bubbles permeate the pond.

Odour disappeared and the pond has a noticeable ‘shimmer’ of sunlight reflected from the minute surface bubbles formed by aerobic bacterial activity.

How the cleansing systems works
Farmer’s Weekly, 15 June 2001

“The effect is almost miraculous. If the pond has been seeded with the right microbes, the anaerobic conditions disappear in a matter of days, and so does the unpleasant smell.”

The bottom of the dam is filled with sludge.

One self priming slurry pump and 50 mm injector was fitted.

1 Minute after start-up. Notice the dissolved air floating to the surface at 2 different spots.

Thick crust formation approximately 1 hour after start-up.
Dissolved air creating aerobic conditions to digest the sludge.

Close-up of the crust on the surface of the dam.

To store the water and irrigate on demand, the grey water is aerated to create aerobic conditions.

Dissolved air floatation plants with ozonation.

Venturis with solenoid valves

Plant at canola oil factory – Removal of oil from the waste water
for use in dog food production.

With an increase in intensive farming, getting rid of smelly effluents has become a problem, even in the wine industry. A soil and irrigation expert discusses a new way to get rid of this waste.

The use of intensive-farming methods is giving way to smelly effluents that are generally associated with factory farming, where the disposal of manure and other wastes is an increasing problem. Nowadays even “clean” agriculture, such as the wine farms of the Western Cape, is contributing to the pollution of our environment.

Dr Jean Piaget, one of South Africa’s foremost authorities on soils and irrigation, says he has seen streams running red with winery waste water. He says he is concerned about both the unnecessary waste of water and the fact that the effluent is so acid that it is bound to harm aquatic life and users lower down the stream.

Dr Jean Piaget is one of South Africa’s foremost authorities on irrigation and water quality

Despite his concern, he says the problem is not difficult to deal with. A system that uses microbes to clean the effluent and air bubbles provided by air “injectors” may be the solution.

However, these injectors are imported from America. Farmers have to pay for them in dollars, and sometimes they have to be matched to heavy-duty macerating pumps that can cope with the detritus in ponds filled with untreated wash water. Many farmers draw the line because they say the pumps are too expensive.

“Wine farmers will happily spend many thousands of Rands on stainless-steel plumbing and imported oak vats,” Dr Piaget says, “but when it comes to cleaning up the mess they make, they unfortunately become a tight-fisted bunch. They don’t see the disposal of effluent as important.

“What we need is a complete change of attitude. Waste products have to be managed as intensively as every other aspect of intensive farming.”

He says farmers should learn how to help nature dispose of agricultural wastes. If the right methods and equipment are used, ponds can become smaller and deeper. They can be more conveniently sited, and free more land for cultivation.

Although effluent disposal might not be a priority for farmers at present, the scarcity of water will soon convince them that steps need to be taken to rectify the situation. Farmers see water as a precious resource and respect it. If it is used to hose down floors or transport wastes, then there is an obligation to clean up the water afterwards so that it is not returned to the environment in a polluted form.

Since the world export markets opened up to SA wines a few years ago, modern irrigation methods, such as drip lines and micro-systems, have not only made land more productive but enabled farmers to cultivate mountain sides and even small pockets of land in semi-urban areas.

SA farmers have proved they are quick to adopt new methods, especially when it comes to water conservation. One example he quotes is the use of plastic sheets that are laid on the land in broad strips. The vines are then planted in holes in the plastic. The method keeps the moisture in the soil, and competing weeds don’t grow in the darkness under the black plastic. Initially farmers were skeptical. Even when the technique was demonstrated on alternate rows in the same field with dramatic results there were reservations.

“They told me that to produce good wine a vine must struggle,” he says. “The plastic made it too easy for the root stock, and the quality would suffer, but these fears have proved groundless, and today the use of plastic sheeting is an accepted practice.”

SA farmers were also quick to use drip-line irrigation. “In fact they were too quick and were using the system before we understood how to space the drippers to suit the soil conditions,” he says. “The initial results were sometimes disappointing, but farmers were not put off, and drip-lines are now making a comeback.”

South Africa also invented micro-irrigation. Dr Piaget helped to pioneer the system. “A mining engineer came up with the idea as a way to keep mine dumps damp to solve the dust problem” he says. “It worked so well and it used so little water that the agricultural potential was quickly realised by a local farmer. The rest of the world learned from South Africa.”

Dr Piaget says SA farmers have been quick to embrace ways to get the best possible value out of the country’s scarce water resources, but they have not been prepared to take a holistic view of intensive farming. He says they spend money on modern irrigation equipment to put good water into the vineyards, but they are not easily prepared to spend money on the treatment of their effluent.

Lack of suitable training in effluent disposal may be one of the reasons why wine farmers are not dealing with their waste effectively. Dr Piaget says he has pointed out many times that viticulture students in Stellenbosch receive too little training in effluent disposal despite the fact that it is a vital part of wine making.

Training wine makers-to-be in effluent disposal is one thing, but getting them to put the knowledge into practice is another.

“I hope the necessary courses have been introduced,” Dr Piaget says, “but even if they have, it will still take a long time before the knowledge is out there on the farms.”

He tells the story of how he received a lecture from an American traffic cop after he had parked in a “blue for disabled” parking bay near a hotel. The gist of the cop’s message was that “in America NO means NO”.

“That’s what we have to learn in South Africa,” he says. “When we lay down the law on how water can be used and how our streams and rivers must be kept free of pollution NO must mean NO.” — by Tony Robinson

The layers build up, creating stagnant conditions. Anaerobic microbes thrive where there is no oxygen, and they get to work generating gas. The water becomes toxic and bubbles with foul gases while septic sludge forms on the bottom.

To remedy the situation, two things have to happen. First the large solids must be screened out and the fine solids removed by means of a delta separator. The clear effluent can be used either directly for irrigation (pumped into large irrigation dams where it is diluted with run-off water) or it can be ponded.

If the water goes into a pond, micro-organisms have to be added, and oxygen has to be introduced at the bottom of the pond to counter the latent anaerobic conditions.

The selected microbes can be introduced in the form of an air-dried powder, and the water has to be aerated. The simple way of doing this is a fountain that circulates the water and ensures that it absorbs oxygen as it is sprayed into the air.

This certainly prevents stagnation, but it is not very efficient. It does not get the oxygen to bottom where the helpful bacteria really need it.

A better way is to force the air right down to the bottom of the pond to reverse the anaerobic conditions. But that’s easier said than done.

If the air is released in big bubbles it stirs things up, and those bubbles shoot straight back to the surface, in this way giving up little oxygen to the water. “What we have to do,” says Bob Hadley of Bio-Systems SA, “is deliver the oxygen in tiny bite-sized bubbles — something the microbes can get their teeth around.”

The device that does the trick is an injector that produces such tiny bubbles that the air looks like white foam in the water.

The effect is almost miraculous. If the pond has been seeded with the right microbes, the anaerobic conditions disappear in a matter of days, and so does the unpleasant smell.