The effects of effluents causes a major problem in the environment and it also creates diseases like respiratory problem, blood cancer etc., so as to avoid this the zero effluent process must be implemented in the industries creating pollution. Also this made the water to get polluted. ZERO EFFLUENT discharge process is possible by adapting the RO i.e., Reverse Osmosis process in the industry. There are many industries which are working under this process and many are in progress.

 

Environmental concerns associated with textile processing had placed the textile sector in a Southern State of India under serious threat of survival. The textile industries were closed under the orders of the Statutory Board for reason of inadequate compliance to environmental discharge norms of the State for the protection of the drinking water source of the State capital. In compliance with the direction of the Board for zero effluent discharge, advanced treatment process have been implemented for recovery of boiler feed quality water with recourse to effluent recycling/reuse. The paper describes to a case study on the adequacy assessment of the full scale effluent treatment plant comprising chemical, biological and filtration processes in a small scale textile industry. In addition, implementation of measures for discernable improvement in the performance of the existing units through effective operation & maintenance, and application of membrane separation processes leading to zero effluent discharge is also highlighted.

 

Traditionally, very little attention was given to water in industry. Water has always been seen as a cheap, readily available resource, an endless supply. However, this is rapidly changing as the costs of water, effluent treatment and disposal are rapidly increasing. There is increasing attention to minimizing the use of water and there are only two options for wastewater collected from any plant: it must either be treated and returned to the receiving waters or recycled and reused within the plant. It sets out to maximize the internal recycle of water, by characterizing the process streams, seeking consistent optimal operation, and applying recovery measures as appropriate to the streams. This requires assessing the viability of such changes and ensuring the treatment plant accommodates any ensuing feed variation. With the “stretch target” of eliminating effluent, material eco-efficiency will be substantially improved, while satisfying manufacturing quality criteria. A transferable, generalised methodology will be devised for the management of waste aqueous streams characterised primarily by suspended and dissolved solids content.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The innovative feature of this technology is:

 

 

In oxidative process, the dyes in the water do not have to be fully decomposed for decolorisation to occur.  As the dyes are oxidized,  they are broken down into small colorless molecules.  The decolorisation process occurs in the smaller molecules of the organic dyes such as in carbon dioxide, water, nitrogen, aldehydes acids etc. depending both on dye molecular structure and on the strength of the oxidation technique.

In oxidation process, the aim is to destroy the chromophore or convert it into a biodegradable form by attacking weak bonds in the dye molecules with suitable oxidizing agents.  Advanced oxidation process is one of the potential alternatives for decolorisation and detoxification of waste water from textile dyeing and finishing effluents.  This process implies generation and subsequent reaction of hydroxyl radical, which is the most oxidizing species after ozone.  Different oxidizing methods are given below:

 

 

REVERSE OSMOSIS

 

In this process the waste water is initially treated with primary and secondary treatment plants and the water is treated in reverse osmosis process where the membranes make the water purified and that water is reusable one. This is zero effluent discharge.

In direct osmosis leachate treatment, the osmotic pressure of salt brine drives the separation. A 9% salt brine has an osmotic driving force equivalent to 1,100 psi. Membrane processes offer several advantages over conventional evaporation and distillation processes:

·                     Lower energy costs—Membrane processes use energy only to pump liquid through the system. No energy is required to heat and vaporize the liquid.

·                     Reliability—The primary equipment for membrane processes is membrane modules and electric pumps. The modules have no moving parts and are easily replaced. Electric pumps have fewer mechanical components than evaporators and require less maintenance.

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Pollution control—Electric-driven membrane systems eliminate emissions released by fuel-fired evaporation or distillation processes.

The industries present in the residential area must be involved in this process as this is a major fact of water pollution. The water that comes out from the industries must be treated effectively and also with a reasonable cost. Cost is the main fact which makes industries not to treat the water. Now, in many of the areas in Tripur, Erode, etc., the effluent water is treated in a effective manner which makes Zero Discharge system.

There are more than 700 dyeing units located in tirupur out of this 200 dyeing units have been started in zero effluent discharge system and the make reuse of the water. In this no water is let-out from the industry. Only industries having high investment had planted the system and so the remaining is in progress. The same situation is on Erode.  

Moreover many of the industries are going to implement the reverse osmosis process as described earlier which makes zero effluent as well as zero water discharge. This will make the environment not to be affected in terms of water pollution. Due to some abnormal circumstance and economical conditions many started undertaking this project.

The ruling by the Madras High Court asking dyeing and bleaching units in Tirupur to install reverse osmosis plants for the secondary treatment of effluents causes consternation in the hosiery town

TIRUPUR, the hosiery capital of India, is undergoing an unprecedented crisis. The Madras High Court ordered the closure of more than 600 dyeing and bleaching units, which are a key element in the production chain in the hosiery garment business.

Having successfully employed stalling tactics, the dyeing units were unprepared for the tough ruling issued by the High Court asking them to install reverse osmosis (RO) plants for the secondary treatment of effluents from these units. The court had, in the course of arguments over the last 10 years, determined that only a zero discharge norm for effluents would save the river.

The problem of pollution in this region is not new. In the late 1990s, after sustained pressure from all quarters, the hosiery industry finally agreed to establish effluent treatment plants. As a result, most of the units in the town now employ some method of primary treatment, which ensures that the effluent does not have colour or odour. However, the salts used in the dyeing process remain in the effluent. The present problems of the dyeing units are related mainly to the question of secondary treatment of the effluents discharge

Roughly speaking, in the absence of any study of the structure of the industry, at the top are the large dyeing units. These are owned by the integrated production units or are those that cater to the needs of the large exporting units. These units, which may number 50, according to industry sources, use about 5-6 lakh litres of water a day for their dyeing operations.

 

 

 The next category consists of the medium-sized units, which use up to 2 lakh litres of water a day; about 150 units may belong to this group. The next group consists of units that use less than 1 lakh litres of water a day; these number about 100. At the bottom of this structure are the small units, numbering about 150. Some of these are run by those who take on lease a unit owned by someone else.  

According to the TNPCB, 8.8-crore liters of effluents, after primary treatment in effluent treatment plants, are being let out into the Noyyal every day. A TNPCB source told Frontline that the Board stipulates that the total dissolved solids (TDS) in the water discharged into the river should not be more than 2,100 parts per million (ppm). It is well known - even the dyeing industry admits it - that the TDS levels in and around Tirupur are way above this norm. In fact, a leading dyer who had established an RO plant more than two years ago, told Frontline that the TDS level in the water in the Orathupalayam dam area is above 9,000 ppm; in summer, when water evaporation is higher, the level of TDS is even higher. He also pointed out that the level prescribed by the TNPCB only related to water used for cultivation.

 

 

According to the DAT there are about 700 dyeing units located in Tirupur. Most of them are either linked to Common Effluent Treatment Plants (CETP) or have their own plants. However, the dyeing segment of the industry is itself stratified. This is essentially in terms of their scale of operations. In SIPCOT (Perundurai), the common effluent plant had been made first before starting up of the industries. Mostly industries on this area are to be involved in this CETP.

The main problem CETP’s are the sludge disposal. The CETP’s are very much scared about this problem as the Govt., ordered not to discharge any of the things from the industries as effluents. So this CETP is not a correct manner to treat the effluents.

Many industries are implemented the ZERO DISCHARGE system around this area itself. Now the govt., recently that there should not be a drop of water coming out of industries and if found the industries will be sealed. The water must be recycled and reused.

 

 

There are many advantages over the zero effluent discharge as it controls the water pollution and the followings;

      Minimizing water consumption.

      Keeping the environment free from pollution.

      Preventing of happening diseases.

      Controls land pollution.

      Controls thermal pollution which controls in BOD.

      No requirement of skilled labour for this process.

      Cost is less when production is more.

      The water can be reused

 

 

 

 

 

 

 

 

 

 

 

Many techniques are readily available for a processor to treat waste water. The basic limitation of a processing unit is the higher installation cost associated with such techniques. Technocrats need to realize that they have to develop simple and cost-effective waste water technologies, that aim at conservation of energy, water, time, and are environment-friendly.

Thus the zero discharge process can be done in an effective manner. The coming and newly formed industries are on the planting of Reverse Osmosis process. Further       R & D is under progress for this to be done in a more effective process.