REPELLENTS FOR DESALINATION OF SEA WATER, RO, NANO, BORON & POLLUTED WATERS WITH CRYO ZLD

2.Desalination of Sea Water Using Repellents

3.Desalination of RO, Nano, & Super Saline Waters

4.Desalination of Polluted Industrial Waters

5.zero liquid discharge - (cold process)

7.suggested industrial process

8.Cost of Desalination of Sea Water

9.Benefits of Repellent Technique

Summary

Pollution, the greatest problem faced by Desalination and chemical industries is being solved by the newly invented salt repellent technique.

A new concept of Repellents for desalting brines have been introduced which removes all the dissolved salts from brines at freezing temperatures.

The same technique is extended to recover potable water from sea waters, high salt brines, as well as to get boron/ fluoride free water.

The process is further extended to treat polluted industrial waters by applying an innovative cold zero liquid discharge (cold- ZLD) system to reduce pollution and at lesser cost.

The process enables to recover 70 to 80% of desalted water that can be used in industries and Agro-cultivation

Remaining concentrated brine be evaporated by solar heat, eliminating pollution to surrounding streams.

No washing of ice is required, enables to recover greater yield of potable water and sea salts.

Process has been patented and know-how is offered on license basis to potential clients

introduction

Water shortage is a pressing issue faced by both households and industries due to various reasons. If the current water shortage trends persist, it will lead to reduced agricultural output, compromised sanitation, and potential regional conflicts. Desalination of sea water has emerged as one of the most effective methods to address this water scarcity.

Although rainwater harvesting is an option, it is often insufficient due to irregular monsoons, exacerbating the water shortage. Therefore, the question arises: How can we meet the ever-increasing demand for water on a consistent basis? Fortunately, many countries possess extensive coastal areas, making sea water the only perennial water source available throughout the year. Consequently, effective utilization of sea water offers a permanent solution to the water crisis.

Sea water contains approximately 3.5% salts, necessitating to remove salts by desalination for human consumption, industrial use, and agricultural operations. There are two well-established industrial processes for desalination: thermal desalination and reverse osmosis. However, both methods pose environmental hazards by discharging highly concentrated brine back into the sea or to the environment. In addition to these methods, natural desalination processes such as evaporation and freezing of water over the oceans exist. Freezing, in particular, is selected for its numerous benefits.

Desalination of Sea Water Using Repellents

When sea water is cooled, it forms sea ice, and during the freezing process, a portion of the salt is rejected (brine rejection), while a small portion of salt is trapped inside the ice crystals. The dissolved salts trapped in ice crystals are too high and not fit for human consumption. Various scholars attempted to remove salts from ice but such process were uneconomical. To overcome this challenge, a new innovative repellent technique has been developed, which repels all salts from ice crystals, thus desalted ice is obtained.

To prove this technique, a batch scale experiment was conducted, wherein a measured quantity of sea water was taken, deaerated, and filtered to eliminate all suspended impurities. Repellents were added to the filtered water, mixed thoroughly, and then cooled to -4°C, a temperature at which ice crystals begin to form. The ice crystals containing small amounts of repellents efficiently repel all salt ions away from the growing ice crystals. As a result, the resulting ice is free of salt ions and can be separated through centrifugation and melted to produce potable water.

Since the concentrated brine obtained from the centrifuge still contained some extractable water, it underwent two additional rounds of desalination, resulting in additional quantities of ice. The ice crystals were then heated to obtain pure potable water. The product was tested, and in different experiments, the Total Dissolved Solids (TDS) obtained varied between 100 and 400 mg/lit. The water yield ranged from 50% to 60%.

The flowsheet is given below:

Desalination of RO, Nano, & Super Saline Waters

The seawater found in many Gulf countries contains high levels of salt, making it unsuitable for drinking or industrial use. Similarly, the concentrates produced by reverse osmosis (RO) and nanofiltration (nano) plants also contain elevated salt concentrations and are often discharged without adequate treatment. To address these pollution issues, experiments were conducted using artificial seawater with a TDS of approximately 70,000 parts per million (ppm), mixed with repellents and cooled to a temperature at which ice crystals form. As the ice crystals grow, the pollutants are repelled away, resulting in ice that is free of contaminants. Upon heating, this ice produces fresh desalted water. Test results presented in the table below demonstrate the desalination of high-salt brine from 69,820 ppm to 240 ppm.

Table 1: Test Results of Desalination of High Salt Brines( (All Figs. In mg/L))

	Test Parameters	Artificial Sea Water	Desalted Water
1	Appearance	Clear Liq	Clear Liq
2	Total Dissolved solids	69,820	240
3	Sodium as Na	27,456	59.4
4	Chlorides as Cl	37,639	103
5	Magnesium as Mg	1,245	4.81
6	Sulphate as SO4	2,011	24
7	Calcium (as Ca)	321	7.93
8	Potassium as K	846	5.9
9	Alkalinity (as HCO3)	144	31
10	Boron (as B)	2.3	0.02

The above experiments clearly demonstrate that the proposed Repellent Technique effectively reduces the salt content of high-salt brines to significantly lower TDS levels, thereby mitigating pollution in the sea.

Desalination of Polluted Industrial Waters

Industries such as chemical, desalination, petroleum, mining, thermal power plants, and others generate significant amounts of effluents, leading to water pollution. To address this issue, a method called zero liquid discharge (ZLD) is employed, which utilizes various treatment technologies like reverse osmosis, evaporation, crystallization, membrane distillation, and forward osmosis to minimize discharge volumes and salt concentrations. One commonly used ZLD method involves evaporating reverse osmosis concentrates in multi-effect evaporators, but it requires substantial energy inputs.

An alternative approach is freeze desalination, which operates at lower temperatures and can recover additional water and salts. This Cold ZLD process reduces environmental damage and costs lesser compared to the traditional method.

Zero Liquid Discharge - (Cold Process)

The Cold ZLD process, which involves the desalination of concentrated brine multiple times to recover additional desalted water and solid salt, has proven to be effective in separating water and salts from polluted waters.

A bench-scale experiment conducted using highly polluted chemical wastewater (Add) “from a Gujarat unit” demonstrated the success of this process. The polluted water, with a total dissolved solids of 40,000 ppm, was treated using repellents, cooled to freeze, and then centrifuged to obtain clear, colourless ice with a reduced TDS of 800 ppm in the first stage. The desalting process was repeated two more times, resulting in desalted ice. The ice from three stages was desalted once again, yielding purified water with a TDS of 415 ppm. The concentrated brine was further evaporated to obtain dry salt. The process flow will be same as in Fig 1 above. Composition of waste water used, desalted water and precipitate obtained by Cold-ZLD process are given below. The results clearly establish that Cold ZLD process separates water and salts effectively from polluted waters. Similar experimental results were obtained with seawater.

Table 2: Test Results of Waste Water(Figs. In mg/L)

	Parameters	Waste Water	Desalted Water	Precipitate
1	Total Dissolved solids	38,860	415	7,34,259
2	Sodium as Na	10177	75.1	164300
3	Magnesium as Mg	983	20.6	1592
4	Calcium (as Ca)	324	3.24	7496
5	Potassium as K	1630	11.1	34503
6	Chlorides as Cl	23286	168	434853
7	Sulphate as SO4	4005	6.76	1577
8	Alkalinity (as HCO3)	445	71.5	2281
9	COD	1558	BQL	13948
10	pH	7.29	7.15	6.44
11	Density, kg/cu.m.	1.02	0.98	0.99
12	Colour	Yellowish	2	-
13	Turbidity	410	BQL	-
14	Moisture	-	-	16.60%

The Cold ZLD process offers several advantages, including reduced environmental impact, maximized water recovery, conservation of resources, cost savings through reduced water usage, and compliance with regulatory requirements.

The process requires various equipment, such as freezer units, melting tanks, centrifuges, compressors, heat exchangers, evaporation ponds, solar panels, pumps, storage tanks, salt collection system and monitoring system. Refrigerants like R404A, R134a, R-1234, ammonia, propane, isobutane, and propylene can be utilized for the operations involved in the process.

Although the freeze desalination with repellents technology is being developed and tested in different settings, the market for Zero Liquid Discharge (ZLD) systems is projected to grow significantly. The increasing environmental regulations, water scarcity, and the demand for sustainable water management practices are driving the growth of the ZLD market. It is estimated that the global market for ZLD will reach USD 8.1 billion by 2025, with Asia Pacific and the Gulf region being the fastest-growing markets.

Overall, the Cold ZLD process shows promise as an effective and sustainable solution for the treatment of polluted waters and the recovery of valuable water resources.

Boron Removal

Boron, while necessary for plant growth, can be harmful to sensitive crops when present in high concentrations in the soil. Additionally, high doses of boron exposure have been linked to abnormalities in human reproductive systems. Various technologies such as adsorption methods, membrane usage, and electrocoagulation have been attempted for removing boron from seawater. Currently, the most effective method is the use of chelating resins. However, these technologies often struggle to reduce the boron content to permissible levels. As a result, research is ongoing to discover new methods for boron removal. One experiment involved the Freeze desalination method with ion-specific repellents, which successfully reduced the boron level from 2.3 to 0.02 mg/L, surpassing the requirements set by the World Health Organization (WHO).

suggested industrial process

The proposed industrial process for freeze desalination, as foreseen by Dr. Wiegandt of Cornell university, involves direct contact freezing of sea water, using liquid butane as a refrigerant. The sea water is mixed with liquid butane, and the mixture is flashed in a freezer under slight vacuum. The evaporation of the liquid butane causes the sea water to freeze into ice. The presence of repellents in sea water drives away the salts, resulting in ice crystals without salt. The ice slurry, containing sticking salt water, is centrifuged to remove the adhering water and obtain salt-free ice.

The desalted ice is then taken to an ice melter, where hot compressed butane gas is passed over the ice. This process melts the ice into water and instantaneously condenses the hot butane vapor back into liquid butane. The cold liquid butane is recycled back to the freezer, while the cold ice water is passed through a heat exchanger to recover heat and cool the incoming sea water, thus utilizing maximum energy.

Cost of Desalination of Sea Water

While other desalination processes require energy to remove 97% of the water to obtain potable water, freeze desalination focuses on removing only 3% of salts from the sea water. The consumption of chemicals in pre-treatment and other operations will be much lower.

In Freeze Desalination, sea water is frozen to a slushy ice by direct contact with boiling butane, which is nearer to freezing point of sea water. The heat required for vaporization of butane (165 btu/lb) Is obtained by the cooling the water (144 Btu/lb) to ice. Consequently, only marginal heat is required to freeze sea water to ice.

In the Melter, compressed Butane vapor condenses on desalted ice and melts the ice, and simultaneously cooling butane vapor to liquid, which is recycled. Thus, the direct freezing and melting cycle promises to achieve high thermodynamic heat balance. So the cost of freezing sea water to ice and back to potable water will be considerably less.

For a freeze desalination unit with a capacity of 10 million gallons per day, the estimated energy consumption will be 5.5 to 8 kWh per cubic meter of desalted water. The absence of ice washing, reduces the energy consumption further lower to around 5 kWh per m3 of desalted water.

Similar reduction in energy consumption is foreseen for other process such as desalination of High concentrated brines, Industrial polluted waters discussed above. Considering above benefits, Freeze desalination may be considered as an alternative process for desalination of saline waters.

To offset the high operating costs, brine mining can be considered. It involves extracting valuable chemicals from the brine, to get high-purity sodium salt, bromide, and iodide salts, which are in great demand. By setting up an integrated desalination plant with a downstream brine mining unit, it would be possible to achieve zero cost for water, reduce pollution, and recover valuable chemicals in abundant quantities.

Benefits of Repellent Technique

The innovative freeze desalination technology offers several benefits compared to other desalination processes, as detailed below:

This is the ONLY process, which can remove salinity of any concentration and can be used to reduce pollution. The traditional desalination process remove 97% of sea while Freeze desalination focuses on removing 3% salts, resulting in lower operating costs and energy consumption. This reduced energy requirement contributes to a lower carbon footprint and helps mitigate climate change.

Additionally, freeze desalination does not involve the use of chemicals or membranes, which are commonly used in other desalination processes. This eliminates the need for chemical treatment and reduces the potential for pollution or contamination of the water. The absence of washing in freeze desalination further decreases energy consumption and minimizes water wastage.

Furthermore, the integration of brine mining in the process provides an opportunity for resource recovery. Valuable chemicals such as high-purity sodium salt, bromide, and iodide salts can be extracted from the brine, reducing waste and creating additional revenue streams. This approach promotes a circular economy and reduces the overall environmental impact of the desalination operation.

In summary, freeze desalination offers a more sustainable and environmentally friendly alternative for the desalination of saline waters. Its lower energy consumption, absence of chemical treatment, and potential for resource recovery make it an attractive option for meeting freshwater demands while minimizing the ecological footprint.

Knowhow Transfer

Take Action Now for Pollution Elimination!

We understand the criticality of reducing pollution, and we’re excited to offer 3 sets of cutting-edge know-how designed to meet the needs of various end users, as detailed below:

Brine Discharge Treatment:

Combats the pollution caused by concentrated brine discharge from desalination plants, including RO retentate water, Nano water, and produced water. Our cost-effective process can reduce salt content from a staggering 70,000 ppm to a mere 350 ppm in just four stages of desalination.

Boron Removal:

Bid farewell to outdated and time-consuming technologies for boron removal. We have made remarkable progress in this area by modifying the process, achieving borate levels as low as 0.02 ppm with superior efficiency.

Salt Removal and Zero Liquid Discharge (ZLD) :

we have developed a groundbreaking Cold ZLD process for removal of all salts. It offers a host of benefits, including significant savings in heat energy, reclamation of valuable raw materials, and the elimination of salty pollutants from effluent waters. In a recent case study, we reduced the TDS of polluted water from a fertilizer unit in India from 38,860 ppm to 415 ppm, COD from 1558 ppm to below quantification limit (BQL), colour from yellowish to colourless liquid, and turbidity to below quantification limit (BQL). These exceptional results demonstrate the outstanding performance of our technology. Given the stringent environmental regulations enforced globally, this project holds immense potential.

Although our work has been limited to bench scale experiments due to the ongoing pandemic, we are confident that the results obtained will translate into successful pilot plant and industrial scale experiments. Our repellents are carefully selected based on their intrinsic properties, ensuring reliable outcomes.

Despite current resource constraints, we wholeheartedly invite all interested clients to step forward and take advantage of this innovative technology. We are prepared to share our results for a small licensing fee for any one or all of the three processes mentioned above. Join us in the quest for a cleaner and greener future.