2013 05 11 09.55.59Island communities provide unique challenges but they all have a requirement for clean safe drinking water and a need to treat and discharge waste water or recycle the water in order to protect their ecosystem.

Dryden Aqua  are marine biologists specialising in the treatment of water and manufacture of AFM, an activated filter media that replaces sand in sand filters.  AFM can eliminate many of the problems of using sand filters to treat freshwater, seawater and waste water.

Tropical islands often depend upon eco-tourism so prevention of pollution to protect the environment including delicate coral reefs are essential for the economy.  Prevention of pollution is essential for any community but particularly stringent discharge consents are required for the protection of coral reefs.  The solution to pollution used to be considered to be dilution,  this is no longer acceptable because many pollutants such as priority chemicals will bio-accumulate,  it may take many years but they will impact on species diversity and can devastate coral reef communities as well as the health and well being of the citizens.

Dryden Aqua are Marine Biologists specialising in water and waste water treatment so we are well placed to provide support in tropical subtropical as well as temperate island or remote communities.  We have worked in the Caribbean as well as Indian Ocean and South Pacific Island.

tubewormDrinking water
1. surface water
2.ground water treatment

1. municipal waste water
2. industrial waste water
3. landfill leachate

Drinking water.

Obtaining clean drinking water is a problem on islands,  ground water is not usually available  because of infiltration of seawater making the water saline.  Surface water can also be a problem with a lack of sufficient reservoir capacity. Also the high water temperature , sunlight and nutrients result in the growth of bacteria and algae, making it difficult to treat the water.  Unlike sand,  AFM does not have a problem treating this water,  which is potable after the addition of chlorine.

saudi arabia aeration system dryden aquaIf drinking water is provided by desalination, then AFM provides the best  means of water pretreatment prior to the membranes. AFM can greatly reduce  biological as well as chemical fouling.  AFM is more efficient than UF membranes as a means of pretreatment prior to RO and is a much lower cost option.

Waste water

The treatment of waste water from municipal waste and landfill leachate needs to be addressed. In this situation there is an advantage having warm water with plenty of sunlight to make the bacteria and algae that treat the eater grow more rapidly.  Water treatment systems such as activated sludge can be delicate and complicated systems to managed.  At Dryden Aqua we have simplified the system down to a process that  only requires a few hours attention every week,  even for very large systems with over 100,000 PE equivalent.

We normally use lagoons with up to a 40 day residence time,  this gives really good performance reducing  ammonium and BOD to less than 1 mg/l.  The water is then filtered by AFM after treatment to reduce the suspended solids to less than 1 mg/l, we achieve a 1x1x1 standard, less than 1 mg/l BOD, ammonium and solids.  The water is then suitable for discharge to the environment or sent on for second use.  Installation is very simple,  three or more lagoons are constructed and lined with HDPE plastic liner.  An air blower is installed with an air ring main around the perimeter of each lagoon and our air diffusers are connect to the air ring main with 1/2" flexible hose. The air diffusers  are then simply thrown into the lagoon.  The systems work well, some 25% of all the diffused aeration systems on landfill site leachate effluent in the UK are fitted with air diffusers and AFM systems from Dryden Aqua.

glass handFor more information on Dryden Aqua contact.

Dr.Howard Dryden
Dryden Aqua Ltd
Edinburgh EH19 3JQ

Latest Articles