MEMBRANE SYSTEMS

The membrane filtration process (MF, UF, NF and RO) offers a wide range of treatment possibilities due to the different combinations of physical configuration, pore diameter, hydraulic arrangement and number of steps, going from suspended solids and turbidity reduction to deionization and disinfection. The variety of physical configurations makes it a very robust technology, covering from flat plate-and-frame membranes (ideal for vibratory systems) to tubular, hollow-fiber and spiral-wound modules. Its applications go from the reduction of suspended solids and turbidity to disinfection and deionization. TECNIAGUAS® offers specialized processes of high performance and cero discharge with V-SEP vibratory enhanced membranes.

º    MICROFILTRATION

It’s a physical separation process used for the removal of suspended solids and colloidal particles. Due to the fact that they are usually made from rigid polymeric materials, the MF membranes normailly have isotropic or uniform composition throughout their cross section. They are usually produced from a mixture of cellulose nitrate/acetate, nylons, polytetrafluoroethylene, polyvinylidene fluoride, polysulfone, polyacrylonitrile and polyacrylonitrile-polyvinylchloride. Unlike RO, the separation process in MF is governed by convective mass transport.

º    ULTRAFILTRATION

Just as Microfiltration, Ultrafiltration is a physical separation process carried out by porous membranes made of polymer materials. The UF pores are smaller than those of MF, which enables them to reduce turbidity and TSS and retain viruses, proteins, microorganisms and parasites. They are usually made in Polyethersulfone or some of the material used in the manufacture of the MF membranes.

º    NANOFILTRATION

NF, also known as Loose Reverse Osmosis due to the structural similarity with the RO membranes, is mainly used for sulphate removal and reduction of color, hardness and micro-contaminants. The NF membranes are made of mixtures of cellulose acetate or polyamide compounds, just as RO membranes, and can also be modified forms of the polymeric membranes used in UF.

º    REVERSE OSMOSIS

RO is a separation driven by the diffusive transport phenomenon through the membrane which, unlike the one used in UF and MF, is non-porous. Due to its molecular structure and behavior, water diffuses through the membrane, which is selective, allowing the retention of contaminants down to ionic level. In general, the process must have a pretreatment stage before the RO in order to remove iron and colloidal silica.

º    V-SEP (VIBRATORY SHEAR ENHANCED PROCESSING)

V-SEP is a membrane filtration system that can handle much higher contaminant loads than conventional membranes thanks to the patented vibratory shear stress technology, which prevents clogging.

One of the several applications of V-SEP is the treatment of produced water, because this technology doesn’t need any pretreatment besides clarification. By filtering the water with a single stage system its possible to get water for reinjection or disposal in saline effluents with a rejection of just 10%, while using a two-stage configuration allows the obtainment of water for irrigation or for disposal in surface effluents with only 20% volume rejection.

Other applications include: treatment of the conventional RO reject, treatment of landfill leachate, dehydration of PVC latex and pigments.

V-SEP is also ideal for applications in which the concentrate or reject have a high added value, as in the production of fruit juice, instant coffee, greek yogurt and others. This is due to the fact that V-SEP achieves much higher concentration levels than conventional RO without damaging the product because of temperature changes.

TECNIAGUAS® is the official representative in Colombia of New Logic Research, the technology's proprietary and manufacturer of V-SEP systems.

    

                               

   

º    ELECTRODIALYSIS (ED)

The ED is a process that removes positive and negative ions from water by retaining them when passing through two anionic and cationic selective semipermeable membranes under the influence of an electric potential with direct current DC. It is often needed to do a pretreatment in order to remove suspended solids and colloidal particles, which might clog the membranes, as well as compounds that could neutralize them, such as organic matter, iron oxide and manganese oxide.

º    ELECTRODIALYSIS REVERSAL (EDR)

This process is similar to the ED, with the difference that the polarity of the electrodes is reversed periodically to release the accumulated ions on the membrane surface. This process reduces the degradation of the membranes due to fouling by turning the product stream into a temporary waste. This method increases the lifespan of the membranes and facilitates the washing process.

NOTE: ED and EDR systems require large amounts of energy, reason why they are not widely used in water treatment facilities.

º    ELECTRODEIONIZATION (EDI)

The EDI is a chemical-free continuous process that removes ionic and ionizable compounds from water using direct current (DC). This process is typically used for the RO permeate polishing and to replace conventional mixed-bed ion exchange systems, which eliminates the need of storage and handling of hazardous chemicals used in the regeneration stage of the resins and problems associated with waste neutralization.

This technology merges the processes of ED and ion exchange by placing a resin between an anionic and a cationic membranes. The selectiveness of the membranes allows only charged ions to pass through, while the water molecules are retained. As in ED, an electric current assists the transport of ions through the membranes, driving the cations toward the cathode and the anions to the anode, leaving only deionized water inside the permeate chamber. The electric current regenerates the ion exchange resin continuously with the aid of an electrically active medium, enabling it to participate in the separation process while minimizing the regeneration downtime.

º    MEMBRANE BIO-REACTORS (MBR)

The MBR merges the processes of activated sludge digestion and membrane filtration. Thanks to the recent technical innovations and significant cost reduction, the applicability of MBR technology for treating biodegradable wastewater has increased dramatically.

In the activated sludge process, the MBR replaces the secondary clarification for solid-liquid separation. The membranes can remove suspended solids completely, leaving the water free of bacteria and viruses.

The permeate is the treated effluent of the system, while the rejection is made up by the concentrated bio-solids, which are recycled back into the bioreactor. Due to the high concentration of biomass in the reactor, it can be much more compact compared to the conventional activated sludge systems.

The MBR membranes can be classified, according to their configuration, in flat, hollow-fiber or multi-tubes, and can be submerged into the reactor or in an external chamber.