Peter Roberts unravels the mysteries of wastewater treatment

Background The stringent requirements of the Groundwater Regulations 1998 make it a criminal offence to knowingly discharge certain contaminants onto the ground in situations where they may be introduced into groundwater, without the prior consent of The Environment Agency. These requirements have led many golf clubs to review their current arrangements for the disposal of waste generated by course maintenance equipment washing and fuelling and also for chemical storage, mixing and disposal. The Groundwater Regulations have designated golf courses as a non-agricultural application and, therefore, commercial waste disposal requirements must be met. The Regulations list many substances frequently used in course management. The options for handling waste wash down water If access to a foul sewer is possible and the sewage treatment provider grants permission to discharge, this offers the simplest short-term solution. There will be a requirement for the installation of oil and petrol interceptors and there will be on going commercial discharge charges from water companies relating to processing the discharged waste. It is expected that restrictions on this type of discharge will increase, as will costs relating to discharge permissions. It is possible that at some point in the future, discharge of equipment wash down water will not be permitted at all.

A second option that has been used is the installation of a sealed underground collection tank or chamber to simply hold wash down water. Initial installation costs can be high and the ongoing cost of the water used will undoubtedly increase. Perhaps the biggest problem with this type of arrangement is that the tank will require regular emptying by a specialist waste handling company. This is already an expensive operation and as the costs of disposal of waste of all types steadily increase the costs to clubs will become very high.

In ground septic type tanks incorporating oil separators will contain the mineral hydrocarbons washed from machines, but other substances such as herbicides, pesticides and fungicides covered by the Regulations will not be contained. As these types of systems discharge excess water to a soakaway or ditch, then a club will be required to obtain a consent to discharge license from The Environment Agency. To ensure full compliance with The Law, a large number of Clubs are opting to contain and treat their waste on site through the use of a biological wash down water treatment and recycling plant that turns contaminants into harmless Carbon Dioxide and Water. Many clubs have already installed, or are looking to install, a treatment system of this type. There are a number of models available in the UK, all working through a process of wash down water containment, collection, cleaning using microbes to digest contaminants and then producing a sustainable treated water supply to re-use for subsequent equipment wash down operations.

What to look for when choosing a biological wash down water treatment system. All of these systems should provide a method of containing the contaminated water within a concrete wash pad. The water is usually collected in an in ground sump within the pad. From here it is fed either by gravity or pumped into the treatment unit. The very nature of course operations means that quantities of materials such as grass clippings, sand and soil will collect in this sump. Look for a system that allows either easy and infrequent cleaning out of this material from the sump, or pumps it to a filtration system that removes it before the water enters the processing tanks and collects it for disposal elsewhere. It is inevitable that some fine suspended solids will enter the tanks and it is essential, therefore, that this be removed by regular flushing out. An above ground processing unit allows this is to be achieved by the simple opening of an easily accessible valve at the bottom of the tank. Just a few seconds of flushing is sufficient to prevent sediment accumulation. Once the contaminant laden water enters the processing tanks, usually in the form of two or more interconnected chambers, it is subjected to processing by biological digestion of the restricted substances. For this digestion to be effective, a number of environmental conditions must be present. The bacteria used in these systems are known as fixed film bacteria and grow on polypropylene surfaces. The larger the surface area of this growing media the more efficient the system, as it allows the water to be in contact with the bacteria for a longer period, known as retention time and provides the best opportunity to digest the harmful materials. Systems using a mesh of growing medium provide this large contact area, which can be as much as 300m², to ensure that complete digestion is accomplished.

An important supporting function is for the system to continuously circulate the water between the processing tank, further increasing the system's ability to process the water and allowing the unit to actually handle more water than the nominal tank holding capacity. The microbes used in these tanks digest the hydrocarbons and pesticides etc in around 12 hours and, therefore, twice the holding capacity of the unit can be treated on a daily basis. A typical eighteen hole golf daily wash down regime can create around 2000 litres (440 gallons) of water to be treated. In addition to this water, any rainfall falling onto the pad will also enter the system and will need to be treated, doubling or even trebling the amount entering the processing unit. Clearly tank capacity must either be able to hold this volume of water or have a recirculation system to allow repeated exposure to the microbes.

The microbes need oxygen to survive and produce healthy aerobic digestion and a good water aeration system is therefore essential. A good system should gently and thoroughly oxygenate the water without creating turbulence that can dislodge the bacteria from the growing medium. The other key environmental requirement is temperature. The bacteria require a temperature above 8°C to become active and need higher temperaturs to work efficiency. In order to ensure this essential temperature and to reduce large variations in temperature the processing unit should be housed in a suitable structure. Locating the unit inside a building or similar housing will also prevent component damage from freezing. It can also protect the unit from damage, accidental or otherwise, and can provide a secure store for chemicals and other potential contaminants within the wash down pad. Some clubs are actually installing systems within containers to provide both temperature control and protection against vandalism. Bearing in mind the volume of nitrates used on a golf course it is also important to consider the system's construction materials. For example, stainless steel where used for tanks has been found to provide effective protection against oxidisation.

Are there any operator Health and Safety issues that should be considered when selecting a waste water treatment system? The answer to this question is yes! Everyday course maintenance operations bring greenkeepers into contact with undesirable and potentially dangerous pathogens, including viruses such as Weils Disease, carried in rat or fox urine or faeces, E.coli naturally occurring in the soil and the water born virus Legionella pneumophila. These can be inadvertently introduced into the wash down unit, particularly from mower washing, where, perhaps, cutting has taken place through an area where foxes have been defecating A wastewater treatment system produces an environment, which has been specially created for baterial proliferation i.e. large area of growing medium and warm, oxygenated water. Clearly, there is now a potential Health and Safety risk of a virus being transmitted through the wash hoses attached to the system and action must be taken to reduce this risk. Treatment systems offering ozone disinfection of the decontaminated water will kill these dangerous pathogens. This method, which is perfectly safe at the levels used, will ensure the welfare of operators and compliance with Heath and Safety legislation.

Summary The key considerations when choosing a wash down water treatment system are: * Ease of access to sumps, filters and processing tanks for regular sediment removal * A large biological growing media * Effective, non-aggressive water aeration * Maintenance of adequate water temperature for microbe activity all year round * The ability to render any waterborne pathogens harmless within the system And finally, as with any equipment or service, choose a supplier who has the resources, including trained personnel, warehousing and spares facilities to support the product and you the customer. *Peter Roberts is MD of Ringwood based amenity water treatment specialist, Hydroscape Ltd.