TECHNOLOGIES – Global Technology Management

Teshnologies

Water Treatment

RAW WATER TREATMENT PLANT

Raw Water Treatment Plant

REVERSE OSMOSIS

Reverse Osmosis

Reverse osmosis (RO) is a water purification technology that uses a semipermeable membrane to remove ions, molecules, and larger particles from drinking water. In reverse osmosis, an applied pressure is used to overcome osmotic pressure, a colligative property, that is driven by chemical potential differences of the solvent, a thermodynamic parameter. Reverse osmosis can remove many types of dissolved and suspended species from water, including bacteria, and is used in both industrial processes and the production of potable water. The result is that the solute is retained on the pressurized side of the membrane and the pure solvent is allowed to pass to the other side.

ION EXCHANGE

ION Exchange

Ion exchange is an exchange of ions between two electrolytes or between an electrolyte solution and a complex. In most cases the term is used to denote the processes of purification, separation, and decontamination of aqueous and other ion-containing solutions with solidpolymeric or mineralic ‘ion exchangers’.

Typical ion exchangers are ion exchange resins (functionalized porous or gel polymer), zeolites, montmorillonite, clay, and soil humus. Ion exchangers are either cation exchangersthat exchange positively charged ions (cations) or anion exchangers that exchange negatively charged ions (anions). There are also amphoteric exchangers that are able to exchange both cations and anions simultaneously. However, the simultaneous exchange of cations and anions can be more efficiently performed in mixed beds that contain a mixture of anion and cation exchange resins, or passing the treated solution through several different ion exchange materials.

ULTRA FILTRATION

Ultra Filtration

UF’s main attraction is its ability to purify, separate, and concentrate target macromolecules in continuous systems. UF does this by pressurizing the solution flow. The solvent and other dissolved components that pass through the membrane are known as permeate. The components that do not pass through are known as retentate. Depending on the Molecular Weight Cut Off (MWCO) of the membrane used, macromolecules may be purified, separated, or concentrated in either fraction.

NANO FILTRATION

Nano Filtration

Nano filtration is a relatively recent membrane filtration process used most often with low total dissolved solids water such as surface water and fresh groundwater, with the purpose of softening (polyvalent cation removal) and removal of disinfection by-product precursors such as natural organic matter and synthetic organic matter.

Nanofiltration is also becoming more widely used in food processing applications such as dairy, for simultaneous concentration and partial (monovalent ion) demineralisation.

Arsenic Removal System

The presence of elevated levels of arsenic in groundwater has become a major concern around the world, especially in South Asia. Up to date, there is no effective treatment for curing health impacts due to the intake of high levels of arsenic. A wide range of technologies has been developed for the removal of high concentrations of arsenic from drinking water. The most common arsenic removal technologies use oxidation, coagulation, precipitation adsorption, ion exchange and membrane techniques.

WASTE WATER TREATMENT

Activated Sludge Process

In a sewage (or industrial wastewater) treatment plant, the activated sludge process is a biological process that can be used for one or several of the following purposes: oxidizing carbonaceous biological matter, oxidizing nitrogenous matter: mainly ammonium and nitrogen in biological matter, removing nutrients (nitrogen and phosphorus

The general arrangement of an activated sludge process for removing carbonaceous pollution includes the following items:

Aeration tank where air (or oxygen) is injected in the mixed liquor.
Settling tank (usually referred to as “final clarifier” or “secondary settling tank”) to allow the biological flocs (the sludge blanket) to settle, thus separating the biological sludge from the clear treated water.

Treatment of nitrogenous matter or phosphate involves additional steps where the mixed liquor is left in anoxic condition (meaning that there is no residual dissolved oxygen)

Extended Aeration Process

The extended aeration process is an advanced activated sludge process which involves treatment of primary clarified effluent with a culture of microorganisms called “mixed liquor/Biomass”. This mixed liquor is retained in the aeration tank and an adequate oxygen source is provided for biological activity and to keep the “mixed liquor” in well mixed condition. The microbes consume the organic waste in the effluent leading to biomass production. The suspended solids and biomass are separated from the treated water in a secondary clarifier. Part of the biomass is returned to the aeration basin as return activated sludge (RAS), to keep the required MLSS level in the aeration tank. The BOD removal efficiency of the extended aeration process is higher than the conventional activated sludge process.

SEQUENTIAL BATCH REACTOR (SBR)

SBR is an activated sludge process designed to operate as a batch process instead of a continuous process. Here aeration and sludge settlement occur in the same tank. The SBR design is a fill-and-draw type activated sludge process where the following steps take place consecutively i.e. anoxic fill, reaction, settling, decanting followed by sludge wastage. The SBR aeration system generally consists of fine bubble air diffusers. In this process, the compressed air is sheared in to small bubbles creating large specific surface area for high mass transfer efficiency between air and wastewater. SBRs produce sludge with moderate settling properties provided the influent wastewater is admitted in to the aeration in a controlled manner. The SBR process is fully automated to control the operation of the various cells.

Filling, aeration and settling is done by PLC based timer operation. The settled effluent is decanted using a decanter mechanism. Sludge is withdrawn and recycled to the tank inlet for maintaining required MLSS and anoxic conditions. Excess sludge is dewatered in a thickener followed by filter press and then disposed.

Advantages of SBR

Excellent treated Effluent quality in terms of BOD, TSS & nutrient removal
Partial removal of colour.
Less footprint area required as compared with extended aeration as no secondary clarifiers.
Better Coliform removal efficiency hence lower disinfection requirements.
Lower power consumption

Moving Bed Bio Reactor (mbbr) / fluidised Aerobic Bioreactor (fab)

The MBBR process is based on the bio film attachment on fluidized media and utilizes the advantages of activated sludge and other biofilm systems without being restrained by their disadvantages. The basis of this process is the biofilm carrier elements that are made from polyethylene/HDPE/suitable plastics. The plastic elements provide a large surface area for the biofilm attachment and optimal conditions for the bacteria culture to grow and thrive. The bacterial cultures digest the soluble organics, gradually grow and detach from the media.

Moving Bed Biofilm Reactor is an aerobic attached biological growth process. It does not require sludge recirculation. Raw wastewater, after screening and de-gritting & primary Clarification (optional), is fed to the biological reactor. In the reactor, floating plastic media is provided which remains in suspension. Biological mass is generated on the surface of the media. Attached biological mass consumes organic matter for their metabolism. Excess biological mass leaves the surface of media and it is settled in clarifier.

Advantages of MBBR

Moderate reduction in BOD/COD
Partial removal of colour
Moderate foot print required.
Retrofitting can be done easily on an existing plant to enhance capacity & performance.
Capable to withstand shock loads

Membrane Bio Reactor (mbr)

The MBR technology is a relatively recent development in the field of biological treatment, using a membrane based process to produce clear treated wastewater with low turbidity, suitable for RO feed. Membranes are placed in the aeration tank to separate treated effluent from mixed liquor. Membranes being an absolute physical barrier ensure removal of suspended and colloidal impurities. MBR applications include retrofits of existing systems as well as installation of new systems, for both meeting the most stringent discharge norms and also for reuse. The MBR process operates at higher MLSS concentration with higher sludge retention time thus producing a low quantum of biological sludge and therefore reducing the sludge dewatering cost. In the MBR process, the liquid solids separation takes place using membranes. The product is a clear, low- turbidity effluent and no secondary clarifier is required in this process.

Advantages of MBR

Excellent treated Effluent quality in terms of BOD, TSS & nutrient removal
Partial removal of colour
Effluent is treated through inbuilt UF and hence good in applications where post treatment is RO
Secondary clarifier not required
Less foot print required

Electro Coagulation

Electrocoagulation (EC), is a technique used for wash water treatment, wastewater treatment, industrial processed water, and medical treatment. Electrocoagulation has become a rapidly growing area of wastewater treatment due to its ability to remove contaminants that are generally more difficult to remove by filtration or chemical treatment systems, such as emulsified oil, total petroleum hydrocarbons, refractory organics, suspended solids, and heavy metals. There are many brands of electrocoagulation devices available and they can range in complexity from a simple anode and cathode to much more complex devices with control over electrode potentials, passivation, anode consumption, cell REDOX potentials as well as the introduction of ultrasonic sound, ultraviolet light and a range of gases and reactants to achieve so-called Advanced Oxidation Processes for refractory or recalcitrant organic substances. A fine wire probe or other delivery mechanism is used to transmit radio waves to tissues near the probe. Molecules within the tissue are caused to vibrate which lead to a rapid increase of the temperature, causing coagulation of the proteins within the tissue, effectively killing the tissue. At higher powered applications, full desiccation of tissue is possible.

DESALINATION

Desalination

Desalination is a process that removes minerals from saline water. More generally, desalination refers to the removal of salts and minerals from wastewater/sea water.

Saltwater is desalinated to produce water suitable for human consumption or irrigation. One by-product of desalination is salt. Desalination is used on many seagoing ships and submarines. Most of the modern interest in desalination is focused on cost-effective provision of fresh water for human use. Along with recycled wastewater, it is one of the few rainfall-independent water sources.

Due to its energy consumption, desalinating sea water is generally more costly than fresh water from rivers or groundwater, water recycling and water conservation. However, these alternatives are not always available and depletion of reserves is a critical problem worldwide. Currently, approximately 1% of the world’s population is dependent on desalinated water to meet daily needs, but the UN expects that 14% of the world’s population will encounter water scarcity by 2025.

Multi Stage Flash Distillation

Multi-stage flash distillation (MSF) is a water desalination process that distills sea water by flashing a portion of the water into steam in multiple stages of what are essentially countercurrent heat exchangers. Multi-stage flash distillation plants produce about 60% of all desalinated water in the world

Multi Effect Distillatioan

Multiple-effect distillation (MED) is a distillation process often used for sea water desalination. It consists of multiple stages or “effects”. In each stage the feed water is heated by steam in tubes. Some of the water evaporates, and this steam flows into the tubes of the next stage, heating and evaporating more water. Each stage essentially reuses the energy from the previous stage.

The tubes can be submerged in the feed water, but more typically the feed water is sprayed on the top of a bank of horizontal tubes, and then drips from tube to tube until it is collected at the bottom of the stage.