Phoslock is a modified clay product which is capable of efficiently removing phosphorus from natural and industrial waterways, process waters & waste water streams.


Frequently Asked Questions What is Phoslock? How does Phoslock work? Is Phoslock environmentally safe? What is Eutrophication? What are blue-green algae? What are the nutrients required for cyanobacteria and algal growth? What is N:P ratio? What are the sources of nutrients? What is a bloom? What are the causes of a bloom? What are the effects of a bloom? What are the options for dealing with algal blooms? Why Phoslock is a better innovative option to treat a water body? What is limiting nutrient? Why phosphorus limitation is better option than nitrogen limitation for controlling the growth of blue-green algae? How does Phoslock affect blue-green algal bloom? How long will take to see the effect of P limitation on the growth of blue-green algal community? In addition to nutrient limitation, what other effects of Phoslock on blue-green algae? How is Phoslock applied? What are the dose rates and costs of applying Phoslock? Where is Phoslock being used and in what applications? What regulatory approvals have been obtained? How often does Phoslock needs to be applied? What is Phoslock? Phoslock is a natural product, produced from modified bentonite clay and developed by the Land and Water Division of Australia’s CSIRO (Commonwealth Scientific and Industrial Research Organisation) to significantly reduce the amount of Filterable Reactive Phosphorus (FRP) present in the water column and in the sediment pore water of a water body. FRP is an important growth limiting factor for blue green algae and other algae. How does Phoslock work? When Phoslock is applied to a water body as a slurry, it moves down through the water column, up to 95% of the FRP is rapidly removed and adsorbed onto the surface, forming an insoluble complex within the clay structure. As the Phoslock settles on the sediment-water interface it forms a ~1 – 3 mm layer. This layer of Phoslock is capable of adsorbing the FRP from the sediment layer on its available binding sites. Once the FRP is bound to Phoslock, it is no longer bioavailabile for use by algae for assimilation and growth. The lack of nutrients in the water body has a direct impact on the proliferation of algae. Phoslock operates over a wide range of pH (~ 4 to 11) and binds with phosphate even under anoxic conditions. Is Phoslock environmentally safe? Yes. During the development of Phoslock, extensive laboratory testing was carried out on a range of test species using the United States Environmental Protection Agency toxicity testing criteria. The CSIRO Centre for Advanced Analytical Chemistry assessed acute and chronic toxicology on a variety of aquatic species with no toxicity effects observed. Since then, the product has received approvals from NICNAS and the DECC in Australia. It can also be imported and sold in Europe under the EINECS system. Extensive toxicity tests were also conducted by independent organization in New Zealand and Australia. Data compiled from independent and in-house sources is available upon request. What is Eutrophication? Eutrophication is a process whereby water bodies, such as lakes, estuaries, reservoirs or slow-moving streams receive excess nutrients that stimulate excessive growth of aquatic plant and algae. Eutrophication is caused by an increase in nutrient levels; usually phosphorus and nitrogen and can result in visible cyanobacterial or algal blooms, surface scums, floating plant mats and benthic macrophyte aggregations. Concentrations of phosphorus of < 0.1 mg/L are sufficient to cause a cyanobacterial (algal) bloom. The decay of this organic matter may lead to oxygen depletion in the water, which in turn can cause secondary problems such as fish kills and liberation of toxic substances or phosphates that were previously bound to oxidized sediment. Phosphate released from sediments accelerates eutrophication. Some lakes are naturally eutrophic, but in many other cases the excess nutrient input results from: (1) anthropogenic origin such as municipal wastewater discharges; (2) industrial effluents; and (3) runoff from fertilizers and manure spread on agricultural areas. Nutrient enrichment seriously degrades aquatic ecosystems and impairs the use of water for drinking, industry, agriculture and recreation. What are Blue-green algae? Blue-green algae, scientifically known as Cyanobacteria, are microscopic single-celled organisms that grow naturally in fresh and salt waters. They are not algae (eukaryotes), but are a type of bacteria (prokaryotes), possessing the ability to synthesise chlorophyll a. Therefore, they act like plants by using sunlight to manufacture carbohydrates from carbon dioxide and water, a process known as photosynthesis. Blue-green algae have vesicles or gas pockets inside vacuoles within their cells that they inflate with gas, thus able to regulate their buoyancy in response to environmental conditions. This is advantageous over other algae as they have the ability to sink and rise at their will and move to where nutrient and light levels are at their highest. What are the nutrients required for algal growth? In addition to light and carbon, growth of phytoplankton (all photosynthetic aquatic microorganisms including algae and blue-green algae) consumes ‘nutrients’. Every replication of an algal cell roughly demands the uptake and assimilation of a quota of inorganic nutrients similar to that in the mother cell. The elements/nutrients most often implicated in the constraint of algal growth are: nitrogen, phosphorus, iron, and one or two of other trace elements, together with silicon - the well known constraint on diatom growth. What is N:P ratio? Since the early twentieth century (1934) it has been recognized (primarily through the late Harvard University scientist Alfred Redfield’s work on Nitrogen:Phosphorus ratios) that the elemental composition of phytoplankton was similar to that of the ocean: 16N:1P. Scientists have accepted this as a constant called the Redfield ratio. However, the canonical Redfield N:P ratio of 16 for phytoplankton is not a universal optimal value but instead represents an average for a diverse phytoplankton assemblage growing under a variety of different conditions and employing a range of growth strategies. The N:P ratio is not fixed in the environment and this is mainly due to the inflow of nutrients from anthropogenic sources such as fertilizers and runoff containing nutrient rich waste such as effluent. During exponential growth, bloom-forming phytoplankton optimally increase their allocation of nutrients toward production of growth machinery, reducing their N:P ratio to ~8, far below the Redfield value of 16. However, when nutrients are scarce, slow-growing phytoplankton that can synthesize additional nutrients acquisition machinery are favoured. This allocation of nutrients results in optimal N:P ratios ranging from 36 – 45. The optimal N:P ratio will vary from 8.2 to 45.0, depending on the ecological conditions. Nitrogen-fixing species (e.g. nitrogen-fixing blue-green algae) often have a higher N:P stoichiometry than non-fixing species. For example nitrogen-fixing, Trichodesmium blooms have N:P ratios ranging from 42 to 125. The differences in N:P ratios between phyla and super families are also significantly different. For example, green algae required N:P ~30 whereas diatom required 10 and Dinophyceae required ~12. What are the sources of nutrients? The natural sources of phosphorus and nitrogen are the small amounts that occur in rainfall. Most of the sources are imported from terrestrial systems or are recycled within the aquatic system. External anthropogenic sources increased nutrients and accelerated the eutrophication. Examples of anthropogenic sources are: fertilizers or nutrients runoff from agricultural land or urban sources, nutrient rich waste such as effluent discharge from sewerage treatment plant etc. Sediments play an important role in the overall cycling of nutrients in freshwater system such as lakes and reservoirs. Molecular diffusion and the convective transfer process through the sediment-water interface control internal loading of bio-available P and N in the overlying water, makes a significant contribution to the total nutrient budget in the reservoirs and plays a critical role in the overall nutrient cycling, and supporting the production of blue-green algae. Bottom sediment acts both as a source and a sink for P and N. The concentrations of soluble reactive phosphorus (SRP) or filterable reactive phosphorus (FRP) in the sediments of a reservoir are usually 3 – 8 times higher than those in the overlying water. Nutrient regeneration from sediment or benthic efflux of inorganic nutrients could supply up to 55 – 100% of estimated nitrogen demand and 30 – 70% of the phosphorus requirements for the initial growth of algae. In large shallow lakes, phosphorus dynamics are generally influenced by physical processes such as wind-driven sediment re-suspension, at time scales from hours to years. What is a bloom? The term bloom generally describes a phytoplankton (including algae and blue-green algae) biomass significantly higher than the water body’s average. Blooms are usually comprised of only one or two species and identified by the dominant phytoplankton type e.g. cyanobacterial bloom, diatom bloom, Anabaena bloom etc. When blue-green algae blooms, i.e. grow to large numbers, they can form thick accumulations on the surface of the water. These accumulations are commonly known as scums. Blue-green algal scums form when large numbers of the algae float to the water surface using vesicles within their cells that they inflate with gas. Coming close to the surface enables them to gain maximum sunlight. What are the causes of a bloom? Cyanobacteria or other algae bloom occurs usually because of high nutrient concentrations (e.g. eutrophication), warm weather, or both. Many other factors play a role in the formation of blue-green algae blooms including temperature, thermal stratification, zooplankton grazing, pH, turbidity and salinity. Most common blooms are caused by blue-green algae. Because these harmful algae dominate over other harmless algae due to their ability to regulate their buoyancy in response to environmental conditions and they can move where nutrient and light levels are at their highest. What are the effects of a bloom? *Toxin production:* Blue-green algae have the ability to produce highly potent toxins. There are four different forms of toxins that can be produced: Hepatotoxins: These attack the liver and other internal organs of the poisoned victim. Some have also been identified as cancer promoting substances. Neurotoxins: These act as neuromuscular blocking agents, damage nerves and can cause muscle tremors, especially in the muscles animals and people need for breathing, leading to respiratory arrest. Endotoxins: These are contact irritants, produce allergic reactions, skin rashes, irritation to eyes, and can cause severe dermatitis and conjunctivitis in people coming into contact with the algae through swimming or showering. They may also cause stomach cramps, nausea, fever and headaches if consumed. Their presence in airborne droplets can cause asthma. Some are also thought to be possible tumour promoters, although this has yet to be shown. Non-specific toxins: These are relatively slow acting general toxins which progressively damage most organs, including the liver. The toxins produced by blue-green algae are colourless and odourless, and can remain present in the water for weeks after the blue-green algae have disappeared. They are not destroyed by boiling affected water. These toxins may poison humans and livestock. Many stock deaths have been documented due to drinking bloom contained water. The toxins can also be concentrated by shellfish, which pose a potential health risk if they are consumed. Cyanobacterial toxins are biodegradable by micro-organisms, but depends on whether the particular biodegradable bacteria are present in water body. *Reduction of dissolved oxygen: Blooms are responsible for consuming much of the oxygen produced, particularly at night or cloudy weather when no photosynthesis occurs. When algae reaches its highest growth phase, it flourishes for a period and then dies. This is known as an algal “crash”. After death, decomposition of these dead algae requires large amounts of oxygen, in turn oxygen deficiency and fish kills. Taste & odour issues: Algal blooms make water unpleasant taste & smell. Cyanabacteria can produce the taste and odour compounds geosmin (GSM) and 2 methylisoborneol (MIB) and these are a significant water quality issues. Cloging filters:* Blooms clog filters on pumps and machinery. *Fluctuation of pH:* Algal blooms cause large daily fluctuations to a water body’s pH. This is due to respiration and photosynthesis of the alga which produces CO2 (on acid) and O2. *Economical loss:* Poor aesthetics of bloom water spoil recreation and tourism and also increase costs of operating water treatment plants. What are the options for dealing with algal blooms? Blue-green algal blooms are a natural part of the aquatic environment. Complete and permanent control of algal blooms is a difficult task and it is likely that resource managers will never be able to completely control algal blooms. A number of methods are available to manage blooms, including: Drain the water body and dredge the sediment. This will remove the phosphorus and other nutrients from the water and sediment. However, this option is messy, disruptive, expensive and a waste of water. Artificially mixing (artificial destratification) the water column by bubble plume aerators to disrupt thermal stratification, which creates turbulence, controls cyanobacteria and reduces sediment release of contaminants. This option is also expensive and not very effective. Minimising nutrient levels in water storages. This may be effective for point sources of nutrients. However, there are several non-point sources and their effects are difficult to minimize. Physical removal of algal scums or restricting light onto the water surface. For instance, covering tanks or dams. These methods are partial and temporary solutions and also not effective particularly on large reservoirs. Treat the algae with an algicide. This is a short term measure because when blooms die or killed by algicides, they decompose and the phosphorus stored in the algal cells are released into the water. The phosphorus is then available to fuel a new algae growth. When blue-green algae die, the cells begin to break down and the toxins are released into the water. Chemical control methods such as algicides or chlorination may cause the cells to burst which can cause toxins to be released into the water. In addition, there may be local regulations in place to control the use of algicides, due to their potential adverse environmental impacts. Treat the water with ‘water treatment chemicals’. 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 concentrations of water treatment chemicals added can make the water acidic and kill sensitive species. The resultant sludge may be expensive to remove and may be harmful to benthic organisms. Why Phoslock is a better innovative option to treat a water body? Phoslock is a better innovative option because it is a novel, non-toxic, permanent solution to control and manage algal blooms. Phoslock was invented and developed by Australia’s most prestigious research organization, CSIRO through 10 years of research and development. Phoslock works through limiting one of algae’s limiting nutrients, phosphorus. Phoslock removes bioavailable phosphorus from the water and continues to react with the phosphorus which is released from the sediment or present in the water column. Phoslock does not have the disadvantages of the other traditional methods of algae bloom control. What is limiting nutrient? A limiting nutrient is one that is necessary for algal growth, but available in a concentration insufficient to support continued growth. Once the supply of this nutrient is exhausted, algal growth ceases. Any nutrients, for example, nitrogen, phosphorus or certain metal can become limiting nutrient for phytoplankton growth. Why phosphorus limitation is better option than nitrogen limitation for controlling the growth of blue-green algae? Limitation of nitrogen is an expensive process, which requires high energy and chemical costs and specialized equipment. Certain microorganisms, including blue-green algae, are able to fix atmospheric nitrogen opportunistically. Removal of metals may disrupt the local ecology, especially that of aquatic plants. Therefore, phosphorus limitation is the most practical means of preventing the growth of phytoplankton, particularly toxic blue-green algae. Phosphorus is an essential requirement of living, functional algae. Phosphorus is a component of nucleic acids governing protein synthesis and of the adenosine phosphate transformations that power intracellular transport. How does Phoslock affect blue-green algal bloom? Nitrogen and Phosphorus are two important nutrients for algal (including blue-green algae) growth and proliferation. The growth of blue green algae is not limited by the concentration of nitrogen in a water body. They are capable of fixing and storing nitrogen from the atmosphere. Their proliferation is related to the competitive advantage they have over other phytoplankton groups where excess phosphorus is available in the water. Phoslock removes soluble inorganic phosphorus out of the water so it is no longer bioavalbile for use by blue-green algae. This in turn increases the N:P ratio as phosphorus is limited. The effect of this is a significant reduction of blue green algae in the water body which leads to a decrease in eutrophication and a decrease in the potential for the water body to contain harmful blue green algal toxins. When nutrient loads are reduced, the phytoplankton biomass decreases. The interpretation of data before and after the application of Phoslock in reservoirs and lakes shows the common trend that: the reduction of blue green algae was likely due to the alteration of the N:P ratio by the use of Phoslock. Filterable reactive phosphorus (FRP) in the water column and pore water at the sediment-water interface was “locked up”, thus changing the N:P ratio. This resulted in P limiting conditions for growth and proliferation of blue green algae. The concentration of blue green algae has also been observed to decrease over time after a Phoslock application. Once placed into a water body, Phoslock will sequester FRP. As the concentration of FRP is reduced in the water body, it becomes the limiting nutrient for blue green algae and in turn, the population decreases (in most applications, to well below regulatory standards). How long will take to see the effect of P limitation on the growth of blue-green algal community? In the events of phosphorus availability, phytoplankton take in excess phosphorus. Storage of excess phosphorus is called ‘luxury uptake’. As a result, the cell may contain 8 – 16 times more phosphorus than the minimum required quota. As a consequence, it is theoretically able to sustain three or possibly four cell doublings without taking up any more phosphorus from the environment. It has been suggested that phosphorus storage in blue-green algae may be greater than in other algae, providing them with a competitive advantage. Phoslock removes soluble inorganic phosphate out of the water so it is no longer bioavailabile for use by blue-green algae. The phytoplankton biomass and the blue-green algal component responds to phosphorus remedial action in four stages: *No biomass reduction if phosphorus in excess of requirements:* This stage occurs in nutrient rich water bodies where nutrients are never growth limiting and there is an unused fraction of the total phosphorus. In these cases there is no immediate effect on phytoplankton biomass or species composition. *Declining amount of unused phosphorus, small reduction in biomass:* This stage of recovery depends upon the behaviour of the phytoplankton in those water bodies where phytoplankton community is dominated by motile algae such as dinoflagellates and buoyant cyanobacteria. As a consequence of the reduced nutrient load, these phytoplankton move to greater depths as they seek additional nutrients. *Phytoplankton biomass falls, minimal unused phosphorus:* The phosphorus concentration continues to decline as a consequence of both the internal and external reduction of the phosphorus-loading. The overall result is a significant decrease in the phytoplankton biomass as p-limitation begins to take effect. *Further decline in biomass and changes in composition of the phytoplankton:* The fourth stage of recovery once the water body reaches its new equilibrium state with a change in species composition. In this stage, the N:P ratio increases and algal speciation shifts from toxic harmful blue-green algae to harmless beneficiary green algae because green algae required N:P ~30 whereas diatom required ~10, Dinophyceae required ~12 and blue-green algae requires less than 29 (depending on the species). In addition to nutrient limitation, what other effects of Phoslock on blue-green algae? In addition to removing bioavailable phosphorus from a water body, Phoslock (bentonite clay) can produce a direct flocculation and sedimentation effect on blue-green algae immediately after application. Blue-green algal data before and after the application of Phoslock in reservoirs and lakes shows the immediate reduction of blue-green algae. Data also reveals that in shallow lakes, flocculated blue-green algae can possibly survive and be re-suspended to the water column after few days. By using Phoslock, FRP would be depleted and effectively break the algal cycle. In deep reservoirs, flocculated blue-green algae are unlikely to survive and be re-suspended to water column. Researchers revealed that if buoyancy controlled blue-green algae move down to greater than 20 meters, their gas bladder may burst due to increased water pressure. How is Phoslock applied? Application takes place using shore based, aerial or boat based equipment. Shore based application involves slurrying the dry granules on site, using site water, and broadcasting the slurry using a pressure hose. Boat based applications also involves slurrying, using on-board equipment and broadcasting by hose and a spray boom. The water will become milky for a few hours after application until the Phoslock settles on the bottom of the water body. The FRP will reduce and can be calculated to fall to below measurable concentrations depending on the amount of Phoslock applied to the water body. What are the dose rate and costs of applying Phoslock? The dose of Phoslock varies between the water bodies. It depends on the amount of bioavailable and total phosphorus present in the water body, history of the water body such as inflows, runoff and sediment conditions as well as chemical properties of water. As a general rule, Phoslock applied at the rate of 100:1, i.e. 100 g Phoslock required to remove 1 g of bioavailable phosphorus (FRP). For smaller applications, the standard dose rate is 200 mg/L, assuming approximately 2 mg/L of total phosphorus in the water body (see Smaller Application Brochure). Phoslock staff will provide a quotation for each water body without any charge. The quoted cost will depend on the client but generally includes 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 a boat or a conglomeration of these methods. Where is Phoslock being used and in what applications? Phoslock is being used in Australia, New Zealand, USA, Indonesia, Malaysia, Singapore, Taiwan, China, Korea and many countries around Europe such as Germany, Netherlands, Belgium, Polland, Hungary and UK. Phoslock will soon be used in Canada, South Africa and India. Types of water bodies being treated include: Large lakes Drinking water reservoirs Prawn aquaculture ponds Irrigation channels and Many smaller applications such as golf course ponds, ornamental lakes, koi ponds and garden ponds 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 provides 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. Water body management can be discussed and planned with a Phoslock Sales Manager. .