WWTP for SIMEM

One factor that is gaining prominence & may prove critical in the evaluation process of a specific exporting company is eco-friendly environment. Eco-friendliness is, in quintessence, effective pollution control, both in the air & on the ground. While belching smokestacks, the aerial factor, are no longer seen, pollution control on the ground is a serious cause for concern for the industry. Effluent treatment has become mandatory for any industry. According to studies by the Indian government institutions, like the CPCB (Central Pollution Control Board), 70% of the pollution in rivers in India is from untreated sewage & the remaining from industrial sources, agricultural run-off and garbage, etc.

Thus, 10,000 cubic mts/day biological plants are being imported from Italy for installation in various industries. The plants are based on Biological treatment & degradation of the waste water which is aerobic in nature. The principle behind Biological treatment of waste water is that it is done by bacteria which feed on its contents. For a successful process, the effluent must be retained for as long as possible so that the bacteria can act upon it for maximum possible time.

Dyeing, printing or processing basic greige material of fabric needs water, leading to its contamination. While dyeing cotton yarn & fabrics, many chemicals are generally used which react with water during treatment, making it toxic. In practice, pollutants are separated from an effluent by using chemical & physical treatment & are being reduced by biological treatment. SIMEM Team in the Environment division has a rich experience in designing Waste water treatment plants the world over with optimum integration of the above processes by using min. amount of chemicals which also saves on expenses. The Biological treatment is started in uniquely designed oxidation tanks. Pre-filtered waste water enters the tank through screen that removes solids. Oxygen is pumped into the tank in the most efficient manner, oxidizing the effluent & allowing the bacteria to feed upon and transform the contaminants present into carbon dioxide, water and energy. Bacteria's are allowed to react with the effluent for 48-72 hours (depending on the Waste water effluent characteristics), unlike other systems where the effluent is moved on between 18-24 hours and then treated with Chemicals.

Homogenization is done in a special tank, where oxygen is trickled in to convert the anaerobic conditions into aerobic, to create an ideal habitat for the bacteria to proliferate. Odors are also removed in this process. In case the waste water does not have the right contaminants that can feed bacteria, nutrients are added for the longevity of the bacteria-for example, on holidays, if the plant is shut.

The oxidation tank is thus the heart of the entire process. Zeroing on this zone, the air is pumped in though diffusers located at the base of the tank which produce micro-bubbles for it to circulate upwards in a spiral, thereby increasing contact time. The aerated mixture is then sent into a clarifier tank. The heavier sludge (which is rich in bacteria), settles down in the clarifier tank & the upper layer of water passes on due to gravity. The sludge, or the organic portion of the effluent, is re-cycled to the oxidation tank to maintain the appropriate concentration level.

Salient features of the plant

•COD, BOD and TSS reduction up to 85 – 90%

•Direct colour removal with only biological treatment plants is up to 55-60% with final removal to the extent of 99% can be achieved thru other treatments

•Tremendous saving in running costs, the major contribution to the daily running cost of the plant is the power consumption. Effectively no chemicals are used. Optimization of techniques developed by SIMEM, long lasting stainless steel equipment

•Fully automatic eco-friendly systems, meeting international norms

•Minimum maintenance & spares required

•Non toxic sludge, which can be used/ sold as manure

In the next stage, if you further wish to improve the quality of Waste water you can opt for Tertiary Treatment to reduce suspended solids, colour, turbidity and colloidal substances. In a separate treatment unit, a small quantity of coagulant & subsequently, the polyelectrolyte is introduced, which removes a high percentage of colour, most of the remaining

Suspended solids & the COD/BOD. The tertiary unit uses a stirrer to churn the effluent, thereby permitting optimum removal. The effluent is now sent to a smaller clarifier unit, in which the balance of the colour and suspended solids are removed almost entirely, before moving into a vertical tank which allows the sludge to settle down. The floating water removes 0.4ppm of cationic polyelectrolyte which is added to hasten the process. Again, the sludge is recycled & the water decanted.

Further Cost Control

This water can be released into a river or re-used in the factory, particularly where the cost of water is high. This again helps in reducing the running cost.

Whenever water is to be re-used, it is passed through a Quartz filter, like sand, before moving into yet another filter for treatment with synthetic adsorbent resins prior to reverse osmosis. The specialty lies in the development of these resins, which remove the residual coloring matter to the extent of 99%, making subsequent treatment & filtration much easier & reducing waste up to 80-90%. Cost is cut down drastically; in fact, the cost at the discharge stage is as low as Rs.5 per cubic meter, against the industrial average of Rs. 10-15 per cubic meter. With the solutions offered by SIMEM one can recover water at an additional running cost of 10 – 15 Rs /m3.

The biological effluent treatment plants from SIMEM offered from JANAKSONS OVERSEAS are very effective in various industries: Textiles, Tanneries, Food & Beverage, and Distilleries etc.

After any system of recovery of water through membrane technology, there is a substantial quantity of reject which is highly concentrated and cannot be disposed off. As a solution provider for waste water treatment and evaporation, JANAKSONS also offers highly economical Turbo-Mist Enhanced Evaporation Solutions from Canada as a substitute to steam evaporator. The running cost of this Evaporator is around Rs. 25-30/m3 as compared to Rs. 150-250 /m3 of the steam evaporator.

The article has been contributed by Mr. Anil Behl, CMD and Mr. Pranay Behl, Director of JANAKSONS OVERSEAS - a pioneering organization dealing in water and wastewater treatment plants from SIMEM - Italy and enhanced natural evaporation system, Turbomist, from Slimline Mfg., Canada.