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Municipal Waste Water - Viable, Dependable Water Resource
Ozone– The Preferred Disinfectant Choice

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INDION Lab-Q System

Municipal Waste Water - Viable, Dependable Water Resource

In many parts of the world, water has become a limiting factor particularly for industrial development. Water resources planners are continuously looking for additional sources of water to supplement the inadequate resources available to their region. Source substitution appears to be the most suitable alternative to meet the growing water demand especially for industrial use. Water scarcity, high cost of raw water, growing demand and stricter discharge norms has created an awareness of the benefits of water recycle that has led to its increasing adoption by industry as well as residential and commercial complexes. However this is, in a sense, a particularized or private approach to reuse of water. A water security policy for sustainable development must embrace a much broader, public approach to water recycle as an effective means of creating a new and reliable water supply, and thus an effective water scarcity solution that should form part of sustainable water management.

Fortunately, the emerging trend is to treat municipal waste water for reuse for industrial applications. Currently, in urban and semi-urban areas, municipal waste is partially treated and disposed off. Instead, treating sewage for reuse considerably reduces the pressure on municipal water supply authorities as well as the load on the environment. There are many progressive municipal corporations who have understood this emerging trend and are in process of implementation waste water reclamation. The major influencing factors while considering municipal waste water recycle are legal, technical, economic and political, as well as social and personal prejudices. Recycled water can satisfy most water requirements as long as it is treated to ensure water quality appropriate for the re-use application. Companies like Chennai Petroleum Corporation, GMR Energy and Madras Fertilisers were among the first in India to use treated municipal sewage for industrial use.

Various technological options to treat municipal waste water are available. For small community systems the technologies for low flow include packaged treatment systems, geotextile filtration and membrane filtration. The major benefit of these systems is that the higher quality effluent can be discharged to ground water for indirect use. These systems are generally easy to operate & inexpensive. Apart from small community uses, they can also be used at military camps, large construction sites disaster relief operations etc.. Constructed wetlands with sufficient land area can provide adequate passive treatment. Aerobic & anaerobic conditions of these systems with microorganisms and vegetation & gravel filters provide the majority treatment. Wetland treatment requires minimal skilled labor, gives a natural appearance and consumes very low energy. However only drawback of these systems are requirement of large area.

One of the most efficient technologies is membrane bio-reactor technology. This has been successful and possible due to the greater understanding of the biological treatment so for adopted for municipal sewage treatment and because of advancements in membrane technology especially ultra filtration membranes. The membrane bio-reactor in combination with reverse osmosis (for tertiary treatment) can offer sustainable results. The performance of this membrane based technology has created a very high level of interest among municipal authorities who are now increasingly contemplating the use of treated municipal waste water to augment the water supplies for industrial as well as other non-drinking applications.

Final disinfection is a major challenge as it needs to balance costs and the treatment effectiveness. Pulsed UV light systems are on the forefront of waste water technology for final disinfection because they destroy pathogens more effectively and at higher rate than traditional disinfection & standard UV systems.

Apart from using membrane technologies, processes that treat domestic waste water to a standard that allows them to be used for low end use or for discharge into inland surface sources without damaging them can be adopted. The LUCAS (Lueven University Cyclic Activated Sludge) process, that incorporates all the advantages of the SBR sequential batch reactor (SBR) while eliminating all disadvantages of conventional systems as well as the variable volume SBR systems, are used extensively. This process treats the waste water to a standard higher then the conventional discharge norms along with removal of nitrogen and phosphorus which makes the treated water suitable for discharge to lakes and rivers without hampering the water body. Removal of these nutrients ensures that the health of the receiving water body is preserved.

Recycled water is most commonly used for non-potable purposes, such as agriculture, landscape, public parks and golf course irrigation, toilet flushing, car washing etc.. Other non-potable, high end applications include cooling water and industrial process water. However, the uses of recycled water are expected to expand in order to accommodate the needs of the environment and growing water supply demands. Advances in wastewater treatment technology and health studies of indirect potable reuse may result in planned indirect potable reuse becoming in the not so far future. more common. Such projects would include augmenting surface water reservoirs and recharging ground water aquifers to augment ground water supplies and to provent salt water intrusion into coastal areas.

Apart from helping meet the growing demand for water, recycle of municipal waste water would also yield enormous environmental benefits such as avoiding the discharge of waste water into the surface waters reduces & prevents pollution; and preserving or augmenting ground water resources.

The future outlook for sustainable development and environment protection would be recycle and reuse of municipal waste water. However it requires public participation, better coordination among the various agencies involved, a need for policy and its implementation and application of latest technologies.

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Ozone– The Preferred Disinfectant Choice

Ozone is a allotrope of oxygen and is naturally formed in the atmosphere due to action of UV light from the sunrays on oxygen in the air. Ozone is highly unstable and reverts back to oxygen within a very short time.

The use of ozone as a disinfectant is gaining popularity because of its

High oxidation potential
Ease of generation
No formation of disinfection by-products
Ability to improve bio-degradibility of complex waste streams including detoxifying waste.

Environmental friendliness

These advantages make it eminently suitable for disinfection as well as process applications in the industrial, municipal and leisure sectors.

Q. What are the applications of ozone?
Ozone is primarily a strong oxiding agent and can be applied for various disinfection and process applications in industry. Ozone was first used by municipalities to control taste, odour and colour as well as for its germicidal action. Applications of ozone in waste water treatment include the destruction or removal of complex organic molecules, cyanides and phenols from chemical waste, etc. In addition, subjecting municipal waste waters to a final ozone process enables their reuse for applications such as wash-water, irrigation, fire fighting systems or for industrial uses.

Ozone is also used extensively in industry in oxidation processes and for disinfection purposes. Typical examples of its use in industry are for pulp bleaching in the paper & pulp industry, in the chemical industry where ozonolysis is necessary for the production of certain substances, and in cooling tower systems where ozone replaces the less desirable chemical biocides. The main applications of ozone can be broadly categorised as follows

1. Industrial
    • Disinfection of raw water
    • Treatment of industrial waste water
    • Process applications of ozone
2. Municipal
    • Disinfection of drinking water
    • Treatment of sewage/municipal waste
3. Leisure
    • Treatment in swimming pools, spas etc.

Some typical applications of ozone for waste treatment are described below:

Complex organic molecules in order to improve biodegradability

Pharmaceutically Active Compounds (PAC’s) and endocrine disruptors

Colour from dye works’ effluent, paper mills, etc.

Surfactants, detergents from washing centres

Cyanides and phenols from chemical waste

Odour elimination from urban waste water plants or industrial flue gas

Odours from condensates/ wash-waters, which can then be recycled

Q. Why is it beneficial to use ozone and what are the advantages? It is an accepted fact that drinking water is disinfected when a residual of 0.4 mg/l of ozone has been maintained for 4 minutes (Typical CT). However, ozone has many additional benefits in the drinking water process.

Use of ozone in drinking water systems avoids the formation of disinfection by-products (DBPs) like Trihalomethanes (THMS) and HAA. These by-products are harmful to human beings and regulations in many countries specify these (DBPs). DBPs are highest when conventional disinfectants like chlorine are used.
In waste water applications, ozone specifically breaks down trace contaminants and enhances the biodegradability of organic substances which are then removed in a biological treatment step.
Finally, combined treatments involving ozone and activated carbon or ozone and peroxide are currently the most powerful means available to water process engineers for the removal of contaminants and constitute a vital safeguard against accidental contamination.
Viruses like cryptosporadium which are not destroyed by conventional disinfectants like chlorine compounds and which are harmful in drinking water system are effectively destroyed by the use of ozone.

Q. How is ozone produced?
Ozone is produced on a commercial scale by means of silent electrical discharge - the result of a high voltage alternating field acting between two electrodes separated by a dielectric and a narrow gap. The feed gas, usually air or oxygen, flows through the narrow gap across which the discharge occurs. The ozone generator’s electrodes are two concentric tubes, an outer tube made of stainless steel and an inner electrode formed by a layer of metal on the inside of a dielectric.

Various innovations in ozone generation have been introduced, by leaders in this field like Ozonia of Switzerland.
Ultra violet light is used to generate ozone typically in leisure applications like swimming pools and spas. The UV based ozone generators do not produce harmful by-products and there is also normaly no need for expensive off-gas mechanisms.

Q. How is ozone used/applied?
Since ozone gas cannot be stored or transported, generation of ozone is done on site. The ozone generated is then fed to the water/waste water to be treated by various means including contact columns, diffuser mechanisms etc. Due to the extremely high oxidation potential of ozone, contact times can be very short.
While dosage rates for drinking water/leisure applications are normally standard, waste water applications will need piloting in the lab and on the field to determine treatment capacity.

Q: What are safety precautions and regulations for ozone?
While ozone systems are built with sufficient safety, it is essential to ensure that excess ozone is destroyed before venting to the atmosphere. With inbuilt safety in the design of ozone generation system, the units are extremely safe to operate as well as being environment friendly.
Its essential however to choose a supplier with adequate knowledge and experience in the area of ozone generation and who can achieve the best overall conditions (prices, delivery and safety) for all types of pilot or industrial plants.

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INDION Lab-Q System

Purified water is an essential resource in all laboratory environment from university research, clinical labs, to bio-pharmaceutical research and pharmaceutical laboratories.

INDION Lab-Q is a compact and convenient laboratory-grade, high purity water (ASTM Type III) system that is an economical alternative for bottled distilled water. It features all the technologies of RO systems with the added benefit of an integral auto sanitisation feature that delivers better than double-distilled quality water from a potable water source. The UV cartridges, in-built sanitisation and microprocessor controls ensure that purity standards are maintained.

Suitable for general, non-critical laboratory applications or as pretreatment for ultra pure water systems, the INDION Lab Q system provides an ideal solution for Type III laboratory grade water requirements. Applications include:

Feed for type I water
Media and chemicals preparation
Rinsing of highly sensitive glassware
Instrumental analysis

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