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Zero liquid discharge for steel industry

  • Zero liquid discharge for steel industry

About the blog

Madhukar Swayambhu
Aquapreneur Agripreneur Sociopreneur IT Professional, Columnist, Philanthropist, Ecologist & Environmentalist
Schneider Electric
Idrica

Steel plants use an enormous amounts of water for a wide range of industrial processes. All these processes are essential and integral part of steel manufacturing and they use large amounts of water and therefore also generate huge quantities of wastewater. The quality of wastewater depends on the process where the water is used and for the purpose for which it is used. Often the quantities are so huge that people perceive it to be impossible to achieve ZLD or Zero Liquid Discharge levels by transforming water back to usable quality and reusing the same in the industrial processes again.

In a steel plant there are host of procedures like cooling or heating (steam based), dust suppression, ore beneficiation process and cleaning of raw material, temperature control (heat treatment), transport of waste materials (ash, sludge, and scale etc., wherein we’ve made water as the transport media), moisture content of coking coal, pelletizing of sinter mix, making of green pellets during the production of iron ore pellets, production of steam and hence power, and granulation of blast furnace slag etc.

The contaminants from a steel plant are also very different from most of the industries but happen to be somewhat closer to mining industry or thermal power plants, due to use or ores and extensive burning of coal. For example, cooling waters are inevitably contaminated with ammonia and cyanide. Contamination of waste streams includes gasification products such as benzene, naphthalene, anthracene, cyanide, ammonia, phenols and cresols, along with a range of more complex compounds categorized as Polycyclic Aromatic Hydrocarbons (PAH). The conversion of iron or steel into sheet, wire or rods requires hot and cold mechanical transformation stages frequently employing water as a lubricant and coolant. In this process there would be a new range of contaminants that would include hydraulic oils, tallow and particulate solids. Moving further to the final treatment of iron and steel products before onward sale, would include pickling in strong mineral acid to remove rust and prepare the surface for tin or chromium plating or galvanization or painting for increasing the longevity of the final product. The two acids commonly used are hydrochloric acid and sulfuric acid, thus get added to the wastewater due to the process of acidic rinse.

With this deadly concoction of chemical toxins, heavy metals, minerals and acids in the wastewater, the major environmental effects of discharge into surface waterbodies will usually cause the following effects –

  1. Toxicity to aquatic life, even causing a mass kill at times,
  2. Reduction of dissolved oxygen suffocating the aquatic life to death,
  3. Sludge deposition due to suspended solids, choking the soil capillaries that would restrict the aquifer recharge through the surface waterbody,
  4. Rise of temperature of water, killing the delicate biodiversity of the wetland,
  5. Formation of a thick layer of FOG laminating the waterbody from the top, and reflecting the Sunlight that would cease the natural photosynthesis process

The Existing Treatment Technologies

So far the ZLD for steel plants have been almost impossible since we have been adopting symptomatic treatment approaches based out of either physics or chemistry or biology or microbiology at the max.

For example, we have a separate process for controlling suspended solids, through sedimentation, followed by centrifugal separation and finally filtration – so you see the entire process is physical here. Again for Fat, Oil & Grease (often collectively referred as FOG in the industry), which primarily gets added to wastewater through the processes like casting, hot and cold rolling mills, pickling, electroplating, and coating operations etc., we involve separate processes on the physical, mechanical levels like skimming, followed by air floatation, may be some gravity separation and finally filtration with single or multiple membranes.

For the control over heavy metals, coming in through blast furnace shop, steel melting shop, or pickling operations, or cold rolling process, and even electroplating, and hot coating operations etc., the chemical processes start, like playing around with the pH of water. If the pH is kept on alkaline side the solubility of heavy metals gets reduced. Adding a coagulation agent to this water will make the metals precipitate, and therefore they can again be removed through some physical process like filtration.

The coke oven plant wastewater carries substantial quantities of phenol, cyanide, thiocyanate, and ammonia, now here enters the biological treatment, or calling it “microbial treatment” would be more apt. A microbial culture is introduced in this wastewater for neutralizing phenol, thiocyanate, free cyanide, and ammonia etc., but there’s a side effect on nitrogen concentration & pH of the water.

Now in spite of all the above processes, the water still needs to undergo at least 3-4 more phases of treatment like Sewage treatment, Terminal treatment, and Breakpoint chlorination and so on. With so many processes in place, and with such high volumes of wastewater as normally produced in a steel plant operations, if it is perceived that making a steel plant achieve a Zero Liquid Discharge status is almost impossible – that’s quite obvious.

The Key Challenges in the Existing System of Treatment

All the processes mentioned above have been developed in multiple periods of time. They are largely non-collaborative, almost like working silos.

Is that a reason behind so many and so tedious processes? Or was it because of lack of understanding the basic nature of the element of water itself? Wouldn’t a holistic approach be simple with a lot of ease of execution too?

Moreover, in spite of all that processing, the water wouldn’t return back to its original native state, which means after all that sludge removal, chemical processes, filtration, sedimentation, aeration, skimming, microbial treatment and what not, the water will still have the residual contents of the contaminants. So the water still remains toxic for any life purposes.

So the final process after all these steps is still dilution and discharge or drain out to a natural resources, usually a river, so that it flows away from the plant.

All the technologies available in the market works on a single philosophy – 95% of wastewater is pure and on 5% is the contaminant added to it. Thus if we extract this 5% waste from it, the rest would become pure again. But this ideology has a fundamental flaw. The problem is lack of understanding of the basic nature of water.

Whenever anything is added to water, the decomposition process starts there and then. What we add is a complex compound and what we take out is a simpler form of the complex, thus there’s something that is left behind always. And thus, water is not back to itself natural self.

In nature, this removal of contamination doesn’t happen at all. Rather all contamination, pollution, impurities or toxins are consumed and digested in the aqua-ecology.

But if this was true, why are our waterbodies getting contaminated across the globe? It is only because our extent of pollution is beyond the natural rejuvenation capacity of water.

So what’s the way out?

The only way out is to increase the digestion and consumption capacity of water so that it is rejuvenated and restored on a daily basis.

Cownomics Technology – An Ecological Approach

Cownomics is a fundamental technology inspired by Vedic Sciences, for resuscitation of native ecology in Soil, water and Air.

The ideology here is completely different from the approach practiced so far in the industry. The fundamental starts from five key elements of life on planet, that are – Soil, Water, Air, Fire and cosmic energy. Because they are the key source of life, they themselves cannot be dead, so they are living ecologies, not dead substances.

Now like every living being, ecology also has its own self-healing powers to take care of the toxics and contaminations disturbing the ecologies.

In a waterbody, the only three possible habitats on the plant – Soil, Water and Air come in a direct contact. This contact in a natural condition provides the biggest pool of single celled organisms, which have the widest variety of metabolisms, ranging from autotrophic to phototrophic, chemotrophic to methanogens, Lithotrophs to photolithographs, prokaryotes to eukaryotes and so on. These organisms have been there on the planet for billions of years and have contributed immensely in making it a livable planet by fixing the toxins in the three habitats. If they are revived through a natural process and the conditions are favorable for them to continue their metabolic activities, they start doing their metabolic activities and fix the toxic material naturally. This is how the chemical toxics get fixed and return back to their origin making the wastewater fresh and usable, basically back to its native state.

We conduct a basic study of the wetland through the map location (longitude & latitude), determining the agro-climatic zone, Soil type, Water type, and Air conditions, kind of toxics coming in, present conditions of the waterbody, kind of weeds, water color, foul smell, mosquitoes, microbial infestation type, vegetation on embankment region and so on. Based on this study a concentrated Ayurvedic concoction is made, which will vary from one treatment to other, based on the above study.

The entire core of the technology is in conducting this study and making this concoction. The frequency, potency and quantity of this concoction will vary from one waterbody to another and one phase of resuscitation to another. Vedic Science says, like human body differs from body to body that compels Ayurveda to always make fresh medicine depending upon the case complexities, similarly every waterbody is a separate individuals case with its own degrees of complexities and imbalances causing the problems. The imbalances are different in each case and all we have to do is to establish a balance between the five elements of life through our process.

The energy engine for the entire treatment process is the cosmic energy which is still available uncontaminated on earth, because it comes in everyday from outside of the planet, i.e., Sunlight. It provides a lot of substance for the trigger to the life forms, from different frequencies of light to photons to heat. If this free energy source is channelized well, the entire resuscitation work is done naturally.

Thus by harnessing two elements fire (human efforts and knowledge) & cosmic energy, the other three are resuscitated.

We dilute the Cownomics© Concentrate in fresh water, and pour the diluted concentrate in the waterbody. When the waterbody is exposed to Sunlight, the life process gets a trigger with the cosmic energy provided by the sun. This re-establishes the life cycle in the water. The smallest entities of life in form of the microbes, which are the part of the natural biodiversity of the said agro-climatic zone, the Soil type and the water type, are revived through the ecological CPR and therefore the natural complex life is restored as well.

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