Chemical Free Waste Water Treatment
Electro Coagulation or Electrocoagulation or EC is a well established technology for the treatment of waste water without the need for process chemicals such as Ferric, PAC or polymers. Instead, it uses a DC voltage which is applied to the waste water using electrodes. The waste water is the conductor allowing the current to pass between the electrodes. The electrical current destabilises the suspended solids allowing them to precipitate. The electrodes are metal, usually mild steel or aluminium and these are sacrificial slowly releasing metal ions into solution performing the same work as chemical coagulants.
Electrocoagulation employs sacrificial metal plate electrodes which are submerged in the water to be treated and across which a DC voltage is applied. The amperage is applied to a prescribed current density for the electrodes and it is this that dissolves the metal ions into solution.
Suspended solids and emulsions are destabilised with the solids separate out and coagulate and hydrocarbons coalesce.
Small amounts of H2 and O2 gas bubbles emerge from the electrodes and can aid flotation of lighter coagulated solids and d-emulsified hydrocarbons. These gas bubbles quickly disperse and heavier solids readily settle.
The hydroxyl radicals OH- produced by the process causes precipitation of heavy metals and partial breakdown of soluble organic molecules.
The EC process produces significantly less sludge than chemical dosing systems such as DAF. Further, the sludge is easy to dewater and is a stable oxide minimising sludge handling and disposal costs.
A wide range of pollutants can be efficiently removed including heavy metals, suspended and colloidal solids, FOGs, fire fighting suppressants, bacteria, BOD, COD, viruses, hydrocarbons, pesticides and herbicides. Typically removal levels are 95%+
EC is a good pre treatment to membrane technologies where high quality water re-use is required.
Pharmaceuticals - Metal Plating - Mining - Oil & Gas - Anaerobic Digestion - Mining - Concrete Crushing - Food Manufacturing -
Meat and Fish Processing - Vegetable Washing - Sludge Dewatering - Algae (Red Tide) Treatment - Textile & Dye - Water Treatment -
RO Pre-Treatment - Ground Remediation - Surface Water - Sewage Treatment - Car & Truck Wash - Coal Washing - Produced Water -
Landfill Leachate - Fracking - Sludge Dewatering - Concrete Products
Examples of Water Waters Treated by SeerdrumEC Technology
Paper Pulp Waste Water
Cellulose rich water after conventional settlement forms the waste water. The suspended solids remain in suspension unless treated. Here the water was treated using mild steel electrodes with a 60 second EC reaction which formed an excellent floc. This floc quickly settled leaving clear water with very low suspended solids which was easily filtered to11 microns simulating an industry standard pressure sand filter.
Cement Contaminated Waste Water
A typical waste water from the manufacture of concrete products, aggregate washing or concrete crushing and aggregate recovery. The gross heavy solids will readily settle but the fine suspended solids remain in suspension unless treated. Here the water was treated using aluminium electrodes with a 60 second EC reaction which formed an excellent floc. This floc quickly settled leaving clear water with very low suspended solids which was easily filtered to11 microns simulating an industry standard pressure sand filter.
Emulsion/Acrylic Paint Contaminated Waste Water
The components of the water soluble paint are so fine the will remain in suspension. They will pass through a 10 micron filter. Here the water was treated using aluminium electrodes with a 60 second EC reaction which formed an excellent floc. This floc quickly settled leaving clear water with very low suspended solids which was easily filtered to11 microns simulating an industry standard pressure sand filter. The floc size has coagulated into much larger particles than the original fine solids and these flocs will not pass a 10 micron filter.
Clay Mine Waste Water
Clay mine rainwater runoff with clay contamination. EC treatment gave a 99.1% reduction in suspended solids. 60 second reaction time in the EC chamber followed by lamella settlement. Energy consumption 0.7 kWhr per m3treated. The photos show the coagulated waste water immediately after EC treatment with the flocks rapidly forming. Then the settlement steps in 5-10 minute intervals. After 60 minutes in the lamella settlement tank the water was clear.
Tannery Waste Water
Waste water from processing natural gut strings. Similar to tannery waste water and includes high TDS, Chromium at 0.6 mg/l and COD at 112,200 mg/l. The photos show the raw waste water, the EC treated water after 15 minutes settlement and the clarified water after lamella settlement.
The analysis of the treated, clarified water showed Chromium at <0.05 mg/l (91.7% reduction) and COD at 10,220 mg/l (90.9% reduction). The approximate EC reaction time was 120 seconds. The energy consumption was around 2.0 kWhr/m3treated. Further testing with mild steel electrodes may improve this. Further, pH correction prior to EC treatment may improve contaminant removal rates. The TDS is not removed.
In most cases, the SeerdrumEC followed by a lamella settlement system is sufficient to treat the waste water without any further processing. And the examples shown above demonstrate this.
The blue paint waste water samples are shown again on the left but this time with with the third sample from the right being the effluent directly from the lamella settlement tank. This will now been cleaned of heavy metals, solids and organic contaminants and subject to analysis can be reused or disposed of to the drain subject to approval.
With some waste waters additional processes may be required to either achieve a good removal of contaminant to deliver a compliant treated water. This maybe a simple as pH correction before the EC reaction and multi-media pressure filtration after the clarification step.
Some waste waters are high in chlorides and other TDS. The EC process will not remove these and to do so, reverse osmosis technology will be required.
Sludge dewatering may be needed for larger SeerdrumEC plants to minimise operational costs.
Vickers Seerdrum can supply and engineer all of these ancillary processes as part of their engineering supply.
The standard SeerdrumEC plants start at 1m3/hr and increase in size to 100m3/hr.
SeerdrumEC Typical Operational Costs
The first two principal operational costs are energy and the sacrificial electrodes. Energy is consumed from the grid as kWhr and the typical energy consumption is typically 0.7kWhr - 1.0 kWhr per m3 water treated. Some difficult and highly contaminated water with very high COD will demand higher energy consumption. The metal electrodes decay at around 23 grammes per m3 water treated.
The third operations cost is sludge handling and disposal. The EC technology has a huge advantage over conventional liquid chemical treatments such as DAF in that the EC sludge is an oxide sludge that readily dewaters without any additional chemicals. It can be passed directly to a thickener and dewatering belt or screw press. The filtrate water is sent back to the process inlet and the dewatered sludge can generally be disposed of to landfill where it will not go back into solution. Conversely, sludges produced by chemical clarification processes are hydroxide types and in much larger volumes. These require additional polymers to assist with dewatering and the sludges will return to solution making there ultimate disposal more difficult and expensive.
Trials and Testing
To test your waste water using SeerdrumEC technology, send a request to email@example.com
Vickers Seerdrum can test waste waters at its works. Generally, 1000 litre IBC are required for initial testing. Sample bottles of the treated water will be returned, with a short report, for the client to analyse. Clients are welcome to visit and witness the EC plant working on their waste water. The trials take place in Cork, Ireland.
Demonstration Plant for On Site Longer Term Trials
Housed within a 6m ISO container for easy shipping, is a 2m3/hr SeedrumEC plant complete with a lamella type settlement tank. The plant includes an fed pump, air scouring, a 1mm manually cleaned screen and manual valves for sludge removal, flow control and general drainage. Also included, if needed, is an acid cleaning pump to clean the metal blades in the EC reaction chamber.
The electrical supply required is 400V 3 Phase and 50 hz. A 20kVA supply is recommended to utilise the maximum amperage if needed.
The control panel included multi function readouts to monitor amperage and kWhr usage. The voltage applied can be varied as can the electrical configuration of the reaction chamber to cater for waste waters with very low to very high conductivities.
The demonstration EC plant is available for trials on site to provide truly representative treatment.
The demonstration plant can be shipped anywhere and is rented to clients at favourable rates. The shipping cost to site and back is the responsibility of the client but Vickers Seerdrum will make the necessary arrangements.
An engineer from Vickers Seerdrum is available to demonstrate the EC technology on site.