GB2366792A

GB2366792A - Nutrient removal from pond water

Info

Publication number: GB2366792A
Application number: GB0022791A
Authority: GB
Inventors: Ian Richards
Original assignee: LEVINGTON AGRICULTURE Ltd
Current assignee: LEVINGTON AGRICULTURE Ltd
Priority date: 2000-09-15
Filing date: 2000-09-15
Publication date: 2002-03-20
Also published as: GB0022791D0

Abstract

A process by which the concentrations of dissolved compounds of nitrogen and phosphorus are reduced in pond waters through the addition to the water of ion exchange resins. The dissolved compounds become adsorbed onto the resins and so removed from solution. As a consequence, the supply of available nitrogen and phosphorus nutrients to algae are reduced and excessive algal growth is prevented. The resins may be in the form of powder or beads or shapes such as discs, filaments, sheets, spheres or foams. The resins may be suspended in the water, within permeable containers if necessary, or may be incorporated into the filters or other parts of water pumping or circulatory systems. After use, the resins may be purified for re-use by removing the adsorbed compounds in ionic solutions.

Description

<Desc/Clms Page number 1> NUTRIENT REMOVAL FROM POND WATERS This invention relates to a process of adding ion exchange resins to ponds or other stagnant waters to reduce concentrations of dissolved nitrogen and phosphorus compounds so inhibiting algal growth Domestic ponds and other stagnant waters occasionally suffer from excessive growth of algae. This can give the water an opaque green appearance which is both aesthetically displeasing and damaging to other pond life. The growth of algae is controlled by temperature, light and concentration in the water of dissolved nitrogen and phosphorus compounds. These compounds are used as nutrients by the algae and elevated concentrations (known as eutrophication) can result in excessive algal growth (sometimes called blooms). Sometimes only nitrogen or only phosphorus compounds are present at elevated concentrations. In other situations, both nitrogen and phosphorus compound concentrations are elevated. If the concentrations of dissolved nitrogen and phosphorus can be maintained at low levels, the excessive algal growth is prevented.

Ion exchange resins can adsorb dissolved compounds in water. Anion exchange resins adsorb negatively charged anions such as orthophosphate (HP04 2-) whilst cation exchange resins adsorb positively charged ions such as ammonium (NH4"'). These ions are important nutrients for algae and reducing their concentrations will inhibit algal growth. A mixture, of anion and cation exchange resins will adsorb both anions and cations and so reduce the concentration of dissolved nitrogen and phosphorus compounds. This invention concerns the addition of cation and anion exchange resins to the pond singly or in combination depending on concentrations of dissolved nitrogen and phosphorus compounds in the water.

Experiments indicate that 1kg of anion exchange resin in the form of beads for example can reduce the concentration of dissolved phosphor-us compounds in I cubic metre of water from 150ppm to near zero within 16 hours. However, other ratios of resin to water can be used according to conditions in the water.

Ion exchange resins can be produced in different physical forms from powders to beads and larger shapes. Powders, beads or foams offer relatively large surface areas per kg of resin and are likely to be preferred forms for use in removing dissolved compounds. Powders or beads can be held in permeable containers to allow contact with the water but easy removal from the water after use. Alternatively, where a pumping or circulatory system is in operation, for example to support a pond fountain or waterfall, the resin can be incorporated in the water filter or other part of the system.

After use, the resins can be discarded or punified by immersion in salt solutions to allow re-use.

Claims

CLAIMS 1. The process of adding ion exchange resins to ponds or other stagnant waters to reduce concentrations of dissolved nitrogen and phosphor-us compounds so inhibiting algal growth
2. The process as claimed in Claim I wherein the nitrogen and phosphorus compounds dissolved in the water become adsorbed onto the ion exchange resin and so removed from solution.
3. The process as claimed in Claims I and 2 wherein the ion exchange resins may be in the form of powder, beads or larger moulded shapes.
4. The process as claimed in any preceding Claim wherein the ion exchange resins, if in the form of powder or beads, may be contained in a permeable container.
5. The process as claimed in any preceding Claim wherein the ion exchange resins may be suspended in the water or may be contained in water filters or other parts. of a water pumping system.