0 Clean Water Through Wind Power

With demand from environmental agencies and utility suppliers to both reduce and better manage water consumption, many sports turf operators are increasingly looking for alternative sources and methods of storing water, both to ensure supplies are available for irrigation and to reduce operational costs. This is leading to the greater use of existing water bodies whilst also providing the impetus for golf clubs and sports clubs to construct new storage facilities in the form of reservoirs.

The primary requirement of both natural impoundments and constructed reservoirs is to provide maximum storage in order to ensure adequate supplies throughout the season. Secondary considerations could include the provision of hazards (within a golf course hole layout), shared use (angling/water sports) or the provision of a wildlife haven. All these considerations increase responsibility on the owner to ensure water quality is maintained at a high level.

Problems with water quality can manifest themselves in many ways, ranging from turbidity and odour, poor species diversity and seasonal blooms of toxic blue-green algae, which can lead to closure orders being imposed on public access. Many of these problems occur naturally within large bodies of water and most are exacerbated when chemical and biological contamination enters through drainage systems. With all these problems though, oxygen depletion in the lower depths is a key factor.

This depletion means that aerobic bottom organisms required for processing waste matter and pollutants die off, anaerobic gases are generated - methane, ammonia and hydrogen-sulphide, in turn leading to poor water quality and odour problems. Nutrients are released encouraging the growth of weed and algae that can block irrigation equipment and eventually the impoundment can fill in with sludge and sediment. Oxygen depletion itself often results from thermal stratification of the water, where the surface water warms faster and forms a thermocline boundary that stops oxygen from migrating down from the surface layer.

Dissolved oxygen is the key and there are many aeration devices available in the market, however these typically only effectively cover a small area and often don't put the oxygen where it is required - at the bottom. Many systems simply surface splash or spray a fountain of water, which only increases the dissolved oxygen concentration in a localised fashion. Water that has more than 70% saturation of oxygen is difficult to reaerate further and as surface water tends to be over 80% saturated anyway these systems are largely ineffective. Underwater-diffused air systems typically utilise offshore compressors to blow air into the water, however near total bottom coverage is required to provide uniform conditions therefore increasing the equipment required and the service requirements. The placement of the reservoir, certainly within a golf environment, often results in the systems being remote from existing power sources, which leads to increased installation costs for power supplies and ancillary controls whilst also adding to the user's energy costs throughout the season.

A wind powered aeration system however provides deep-mix aeration and circulation, which greatly accelerates the natural aeration process and significantly increases the oxygen transfer rate. With a deep-mix system a gentle circulation pattern is established that forces oxygen rich water back down to the lower strata. It is this deep mixing that stimulates the breakdown of wastes and limits the release of nutrients through the restoration of an aerobic environment at the bottom of the lake. All of this is achieved without the need for electrical supplies and additional controls resulting in significant savings in both installation and running costs.

New on to the market is the LAS Pond 1, a wind powered aerator which provides an environmentally friendly way to address water quality whilst producing crucial reaertion and destratification of water impoundments. These units can aerate to almost unlimited depths, and cover a relatively large area (up to 2 ha (5 acres) per unit), whilst requiring wind speeds as little as 5mph (typically producing 1500 LPM flow at average wind speeds).

What are the direct benefits? Healthier aquatic life, reduced algae and odour problems, cleaner water with less sludge accumulation, better quality of water for irrigation use and a more active and thriving ecosystem. All of these can be achieved whilst reducing operating costs and ensuring a clean sustainable water supply is available for future users.

The LAS POND1 is available from Irrigation Control Ltd in partnership with LAS International (Europe) Ltd. Contact Lee Knight Tel: 01606 558927 Fax: 01606 862882

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