Wastewater Electrochemical Treatment Technology (WETTTM)
A New Approach
Terragon’s WETTTM is a new patented approach that can be used to treat water for recycle or reuse and treat water for safe discharge.
The approach is based on cutting-edge electrochemistry, and a design philosophy which eliminates biological treatment, disposable filters and membranes, and the need to add chemical reagents.
The WETTTM approach is particularly well-suited for:
- Decentralized water treatment
- Situations with low to moderate flowrates
- Variable influent loadings and concentrations
- Highly contaminated wastewater
- Need for automated and maintenance-free operation
- Need for on/off capability
The Products
Terragon began developing WETTTM in 2007 with support from a number of high-profile organizations. Terragon has developed customized WETTTM systems for the treatment of:
The WETTTM technologies are part of Terragon’s exciting effort to develop Total Resource Utilization (TRU) habitats with Zero Waste Discharge and can be integrated with MAGSTM, Terragon’s unique energy appliance fueled by waste.
The Process
All WETTTM systems consist of one or more modular WETTTM units based on electrochemistry, supplemented by simple pre-treatment and post-treatment units depending on the wastewater being treated.
Central to all WETTTM systems is a marinized Electrocoagulation (EC) unit which has been perfected over the years to overcome the difficulties that are common to many simple EC units available commercially.
The EC unit has self-cleaning and anti-passivation features. It operates continuously and performs automated contaminant coagulation, flocculation, flotation, separation and removal in a single enclosed reactor. No polymer addition, settling or flotation tanks, or filters are required.
Typically, the EC unit removes about 75% or more of the total suspended solids (TSS) and chemical oxygen demand (COD) present in the wastewater, along with complete removal of phosphorus and heavy metals.
Each EC unit contains only 1 pair of sacrificial metal electrodes, given the ability of the system to operate at comparatively high current densities. This simplified approach means that installation of a new set of electrodes take less than 10 minutes, which depending on system design may be required every 1-3 months.
There are two sizes of EC unit available; a smaller one that treats at 1.0-1.5 Lpm, and a larger one that treats at 5-7.5 Lpm. Multiple EC units can be arranged in a parallel fashion to treat larger flowrates than can be accommodated by a single EC unit.
For highly concentrated wastewater, or for removal of dissolved organics remaining after EC treatment, Terragon has developed a unique world-class expertise in the selection, design, and application of Electrochemical Oxidation (EO) using Boron Doped Diamond (BDD) electrodes.
BDD electrodes are not sacrificial and do not need to be periodically replaced, as with the sacrificial EC electrodes. BDD electrodes can be manufactured in various ways, and Terragon’s extensive development effort has identified a single manufacturing approach able to yield BDD electrodes that are robust enough for long term wastewater treatment.
The EO unit consists of a reactor which houses the BDD electrodes, and an approach developed by Terragon that allows a semi-batch but continuous trouble-free operation.
EO generates powerful oxidants near the BDD electrode surface in the form of hydroxyl radicals, as well as weaker oxidants in the bulk solution (depending on the ions present in the wastewater). EO treatment is sufficient for complete disinfection of even the most contaminated wastewater.
The EO reactor based on BDD electrodes is a safe and practical approach for use in decentralized applications. Although other approaches can be used to generate hydroxyl radicals, they typically involve the use of photocatalysts, UV light, and/or chemical addition and are far less convenient.
Depending on the application, it is sometimes necessary to reduce the residual oxidant content remaining after EC and EO treatment. Terragon has developed an electrochemical approach involving sacrificial metal electrodes. This eliminates the requirement to add reducing agents such as sodium bisulphite or other compounds.
Terragon has also developed a unique floating bead filter (BF) which delivers exceptional performance and can be used to remove all traces of residual turbidity. The BF is fully automated, maintenance-free, and has no consumables.
Depending on the application, it is sometimes necessary to precede or follow the electrochemical units with non-electrochemical units.
Terragon has developed a compact laminar plate separator (LPS) for removal of large suspended solids, as well as a novel free oil separator (FOS) for removal of free oil in oily water treatment systems.
Depending on the treatment requirements, there is sometimes a need for units after the primary electrochemical units in order to polish the treated effluent or add an oxidant residual.
Terragon makes use of granular activated carbon (GAC) columns to remove small traces of residual organics. Various approaches are used for prevention of biofouling and addition of a chlorine residual.