re: gets dose of medicine What is Phoslock?Phoslock is a...

re: gets dose of medicine What is Phoslock?

Phoslock is a modified clay product which removes soluble phosphorus from all kinds of water bodies including fresh, brackish and saline water. Removal of phosphorus reduces the ‘eutrophication’ commonly shown by algal blooms in water.

What is Eutrophication?

Eutrophication means nutrient rich – usually referring to the presence of excess phosphorus and nitrogen. Phosphorus is easier and more cost effective to control to make water bodies clean.
Apart from algal blooms, eutrophication can lead to fish kills with loss of other aquatic life, it can kill animals that drink the water and some types of algae can make humans very sick.

How was Phoslock developed?

Phoslock was developed in Australia by scientists at the Federal Government owned CSIRO and funded jointly by the Western Australian State Government's Water and Rivers Commission and the Swan River Trust. The research was initiated in late 1994 to remediate the Swan and Canning Rivers by reducing the level of phosphorus.

What is Phoslock made from?

Phoslock is made from naturally occurring products. The manufacturing process involves mixing in water a naturally occurring clay (bentonite) with a rare earth (lanthanum). The lanthanum is absorbed into sites within the bentonite and becomes the active element to remove phosphorus.

How does Phoslock work?

When Phoslock is applied to a water body, the phosphorus present in the water column is attracted to the lanthanum to produce lanthanum phosphate. Lanthanum phosphate is ‘insoluble’, thus locking up the phosphorus within the bentonite.
After a couple of hours, the Phoslock will settle on the sediment and so long as it has active sites it will continue to react with any phosphorus either released from the sediment or present in the water.

Is Phoslock environmentally safe?

Yes. Phoslock has been the subject of extensive ecotoxicity and other testing in a number of countries including Australia, USA, China and New Zealand. The most recent tests were conducted in NZ on algae, juvenile fish (rainbow trout) and water fleas (crustacea). These are known to be very sensitive indicators of contamination or pollution. These tests demonstrated that Phoslock under NZ ERMA guidelines showed that the risk to these is so very low that Phoslock is regarded as ‘non-toxic’.

What are the options for dealing with algal blooms?

There are four main strategies to deal with algae:

1. Drain the water body and dredge the sediment. This will remove the phosphorus from the water and possibly from the sediment. This alternative is messy, disruptive, expensive and a waste of water.
2. Treat the algae with an algicide. This is a short term measure as the phosphorus is returned to the water when the algae die and provides food for more algae to grow. Care is required as dangerous toxins may also be released into the water as the algae die. Most algicides are copper based which are not environmentally friendly and have been prohibited from use in many parts of the world.
3. Treat the water with ‘water treatment chemicals’ such as alum or iron salts. While this is a common form of control and appears cheap, the removed phosphorus can be re-cycled by bacteria. Re-treatment is then required. To get to the very low levels of phosphorus required for good water quality, the amounts added can make the water acidic and kill sensitive species. The resultant sludge may be expensive to remove and may be harmful to the benthic organisms.
4. Treat the water with Phoslock. The Phoslock will remove the phosphorus in the water and will continue to react with phosphorus released from the sediment or present in the water. Phoslock does not have the disadvantages of the other methods.

What are the costs of applying Phoslock?

As a general rule, most eutrophied water bodies require about 250g per square metre of surface area or 2.5 tonnes per hectare. Analysis of the water will confirm this or indicate if a greater amount of Phoslock is necessary.
The quoted cost will include delivery to site, application and pre and post treatment testing. The cost will vary based on quantity of Phoslock, size of water body, accessibility and location of site and whether application takes place from shore or from a boat or both.

Where is Phoslock being used and in what applications?

Phoslock is being used in Australia, New Zealand, USA, Taiwan, China, Korea, and the Netherlands. It will soon be used in South Africa and India. Types of water bodies being treated include:

* Large lakes;
* Sewage treatment ponds;
* Agricultural waste holding ponds;
* Golf course ponds;
* Municipal ponds;
* Ornamental lakes in universities, office parks;
* Industrial pits;
* Prawn farms; and
* Artificial wetlands.

How is Phoslock applied?

Application takes place using either shore based or boat based equipment.
Shore based application involves slurrying the dry granules on site using site water and broadcasting using a pressure hose. Boat based application also involves slurrying, using on-board equipment and broadcasting by hose and a spray boom.
The water will be milky for a few hours after application before returning to its previous state, except the phosphorus will be reduced and will fall to below measurable amounts with the right level of application.

What regulatory approvals have been obtained?

(a) Australia

Registration for Phoslock has been obtained under the National Industrial Chemical Notification and Assessment Scheme (NICNAS) for commercial use in water treatment in Australia.

(b) United States

The US EPA has issued a Pre Manufacture Notice for Phoslock. All toxicity tests that have been completed in Australia for NICNAS registration have conformed to the same toxicity characterization leachate protocol (TCLP) that is used in the US as well as many other countries.

(c) New Zealand

At a national level, ERMA approval to import and sell Phoslock has been obtained. Environment Bay of Plenty has issued a Resource Consent to permit the treatment of Lake Okareka in the Rotorua region.

(d) European Union

Phoslock has been certified as being neither a "Biocide" nor a "New Chemical".

(e) China

The Lake Dianchi Authority (LDA) has approved Phoslock for use in listed projects in Yunnan Province. Listed projects include a number of large lakes and rivers in and around Lake Dianchi as well as sewage treatment plants and wetlands in the area.

How often does Phoslock needs to be applied?

Treatment with Phoslock is a “reset” of the ecological clock of the water body. That is, it returns the water body to the phosphorus level which is likely to have existed many years prior to the events which have given rise to the increased levels.

Management strategies limit additional nutrients finding their way into the water body. However, it is rarely possible to prevent nutrients building up as there are various sources including runoff and waste from birds and animals. Phoslock may remain active and capture phosphorus from natural sources for many years.

However, if there are unmanaged phosphorus inputs, Phoslock treatment may be required at much more regular intervals.