• Water quality testing: Different brands offer niche specialities and strengths. We therefore offer a range of products from different brands, selecting according to your specific need. From  our experience, we select from Eutech, Extech, Lamotte, XS Instruments, Hanna, Horiba, Lovibond, Hach, AZ Instruments and Milwaukee analytical equipment.
• We have a diverse range of screening products such as nylon mesh, HDPE plastic mesh and stainless steel.
• For air supply, we have regenerative side-channel blowers, roots blowers, centrifugal blowers, portable 12 volt blowers, low pressure fans and more.
• We have a robust range of water heating equipment, including titanium heaters.
• The Wilo brand pump range covers every pump application. Other pump brands are also available. We supply DC solar pumps and AC pumps.
• Our water treatment and processing includes the bioremediation bacterial products, ozone, UV sterilizers, biofiltration media & systems and bead filters.
• We have a good range of PVC valves for various applications.
• We have equipment for the fields of Limnology, Oceanography and Hydrobiology
• Medium sized water treatment to produce drinking water by reverse osmosis

Some products will be listed here, but we handle your customised request to source what you need.

Our fully submersible titanium heaters provide reliable service for years. They do not corrode in fresh or sea water. Single phase and three phase elements are available, as are the electrical control panels.

Water treatment technologies overview

A variety of water treatment technologies are often needed to work together to purify raw water. Sourced mostly from aquatechtrade.com.

Screens and meshes

Screens such as physical screening and drum filters are used to remove particulate material (solids) and debris from raw water. Screens reduce solids loading to various degrees. Numerous types of cartridge filter also serve as screens and are effective down to fin micron filtration levels.

Gravel filters and sand filters

Turbidity, finer solids and algae can be removed using gravel filters for industrial systems and sand filters for domestic and commercial applications. We have quite a few sand filter options available.

Slow sand filters

Turbidity, algae and microorganisms can also be removed using slow sand filters. A simple and reliable process, slow sand filtration is often suitable for the treatment of small supplies provided that sufficient land is available. Slow sand filters usually consist of tanks containing sharp sand (size range 0.15-0.30mm) to a depth of between 0.5 to 1.5m.  Ecotao does not build slow sand filters.

Activated carbon

Using physical adsorption, contaminants are removed using activated carbon. The amount and type of the carbon, the nature and concentration of the contaminant will affect this, retention time of water in the unit and general water quality (temperature, pH, etc.).

One of the most common mediums is granular activated carbon (GAC), although powdered activated carbon (PAC) and block carbon are also sometimes used. We supply bags of activated carbon for larger filter applications and filter media in replaceable cartridges (a particulate filter at the outlet of the cartridge is used to remove carbon fines from the treated water).

Aeration

Aeration, such as with side-channel air blowers,  transfers oxygen into water and remove gases and volatile compounds by air stripping. A common method is packed tower aerators because of their compact design and high energy efficiency. To achieve air stripping various techniques can be used including counter current cascade aeration in packed towers, diffused aeration in basins and spray aeration. Ecotao supplies air blowers for general aeration, lamellae for the packed tower type aeration and “bakki showers”. Bakki Showers are a type of trickle filter where water delivered by a spray bar falls at its own rate through biological filter media. As the water flows through the media it is aerated air, which keeps the oxygenation of the tank water very high. Bakki Showers also creates a very oxygen-rich environment for the bacteria providing biological filtration, which increases their effectiveness. The Bakki shower trickle filter is an efficient filtration system serving both as a biofilter and for aeration.

Membrane processes

Reverse osmosis (RO), ultrafiltration (UF), microfiltration (MF) and nanofiltration (NF) are the most used membranes for water treatment processes. Previously applied to the production of water for industrial or pharmaceutical applications, membranes are being applied to the treatment of drinking water. Membrane processes can provide adequate removals of pathogenic bacteria, Cryptosporidium, Giardia, and potentially, human viruses and bacteriophages. In a notable case study, companies from the Netherlands and Denmark are working on integrating enzymes into membrane technology for the removal of pesticides and pharmaceutical residues from drinking water.

Ultraviolet (UV) water treatment

Ultraviolet (UV) light sterilizers can kill microorganisms such as bacteria, algae, viruses, and fungi in water treatment processes. The wavelengths of UV light range between 200 and 300 nanometers (billionths of a meter). The ultraviolet radiation wavelength is at 254 nm from special low-pressure mercury vapor lamps. This is the optimal wavelength for disinfection and ozone destruction. Termed germicidal, they can inactivate microorganisms, such as bacteria, viruses and protozoa. UV lamps are usually housed in UV transparent Teflon or quartz glass tube sleeves and so do not contact the water.

UV disinfection is suitable technology for potable drinking water as a primary disinfection method. For a secondary form of disinfection, it is suitable against microorganisms, such as Cryptosporidium and Giardia, which can be chlorine-resistant.

In addition, UV light (either alone or in conjunction with hydrogen peroxide) can destroy chemical contaminants such as pesticides, industrial solvents, ozone and pharmaceuticals through a process called UV-oxidation.

Under ideal conditions, a UV unit can provide greater than 99% reduction of all bacteria. However, even with this performance, ultraviolet disinfection has three potential limitations: “point” disinfection, live cells not being removed and the “shadow effect” where particles in the water prevent higher percentage sterilization.

“Point” Disinfection can occur if the UV units only kill bacteria at one point in a watering system and do not provide any residual germicidal effect downstream. This can be both an advantage and disadvantage. If just one bacterium passes through unharmed (100% destruction of bacteria is not guaranteed), there is nothing to prevent it from attaching to downstream piping surfaces and proliferating.

One notable development to UV systems is the scaling up of light-emitting diode technology, known as UV-LED (from 2018).

Ozone water treatment: ozone generators

When oxygen in air is exposed to the discharge of a powerful electric current, ozone (O3) is formed. Ozone can be used throughout water treatment, for example during pre-oxidation, intermediate oxidation or final disinfection, as it has excellent disinfection and oxidation qualities. Usually, we recommended to use ozone for pre-oxidation, before a sand filter or an active carbon filter (GAC), as these will remove the potentially toxic residual ozone. Also, following ozonization, these filters remove the remaining organic matter.

An electric discharge field generates ozone, as in the CD-type commercial ozone generators, or by ultraviolet radiation (UV-type ozone generators). Electrolytic and chemical reactions also produce ozone.

An ozonation system usually includes passing dry, clean air through a high-voltage electric discharge, i.e., corona discharge, which creates an ozone concentration of approximately 1% or 10,000 mg/L.

Ozone is injected into water through a venturi or air blower into the raw water to be treated. Since the ozone will react with metals to create insoluble metal oxides, post filtration is required.

Ozone is highly reactive and, as a result, has a very short half-life once dissolved into water. The natural reaction is for ozone to return to its oxygen form, with a reaction time typically taking 10-20 minutes at 20 degrees Celsius.

Advantages of ozone water treatment include the minimization of inorganic, organic and microbiological problems and taste and odour problems.

Water treatment chemicals

Chemical disinfection of drinking-water includes any chlorine-based technology, such as chlorine dioxide, as well as ozone, some other oxidants and some strong acids and bases. Except for ozone, proper dosing of chemical disinfectants is intended to maintain a residual concentration in the water to provide some protection from post-treatment contamination during storage. Commercial products that are used in water treatment and disinfection include Virkon S, Halamid, hypochlorous acid and chlorine in various forms (calcium hypochlorite, sodium hypochlorite).

We may add a number of other chemicals in water treatment. These include substances such as sodium hydroxide for adjusting pH and, in certain circumstances, chemicals for fluoridation of drinking-water.

Biofiltration of biological filtration

Biofilters create a surface area for the adherence of Nitrosomonas and Nitrobacter type bacteria that convert ammonia that is toxic to fish and invertebrates to less toxic nitrates in water.

Settling technologies

Tube settlers or lamellae in tanks is another technology used to increase the surface area for solids settling and so provide a viable industrial solids settling method. Cyclones, vortexes, radial flow settlers and hydrocyclones are other methods of solids removal from water.

Protein skimmers (foam fractionaters)

Another viable technology for the removal of the finest suspended solids is the use of protein skimmers, also called foam fractionaters.