In this invention are presented methods and device embodiments that use acoustic pressure shock wave technology in water/fluid treatment processes such as turbidity and total suspended solid reduction, membrane filtration, algae removal, disinfection processes, water softening procedures, separation of radioactive heavy water from normal water, sludge dewatering and desalination of salted water/fluids, including brine that has a high concentration of salt in water/fluid.
Although water exists in abundance on Earth, it is increasingly unreliable, insufficient and declining in quality. The main sources of drinking water are lakes, reservoirs, canal, ground water, sea water, rain water, etc. In the modern era, water is becoming a strategic resource and harvesting the water suitable for the needs of various industries such as petro-chemical industry, steel industry, oil and gas, power generation, municipal supply, mining, chemical industry, and consumer goods requires the introduction of new technologies that makes more efficient the use of water and waste water cleaning for re-use/recycling. The quality of water is determined by many factors such as physical, chemical or biological parameters and its final use (for drinking or for industrial processes)
For example the drinking water must be subjected to a treatment process, to achieve the standard quality for drinking purpose. General treatment of drinking water is consisting of several stages to remove or reduce suspended, dissolved solids and microbial pollutants. Cleaning of used water and recycling represents the most important approach that can conserve the water and improve the overall efficiency of using water in any industrial/household processes associated with modern human society.
An important parameter for the drinking water quality is called turbidity, which is a measure of the degree water loses its transparency due to the presence of suspended particulates (the murkier the water, the higher the turbidity). Turbidity is caused by suspended substances or dissolved substances such as clay, silt, oil, finely divided inorganic and organic matter, soluble colored organic compounds, plankton and other microscopic organisms. Conventional methods for decreasing turbidity and reduction of total suspended solids/pollutants in water are coagulation/flocculation (performed in special large tanks called clarifiers or settlers or weir tanks), rapid/slow filtration, microfiltration (0.1-10 micrometer pore size), nanofiltration (2-100 nanometer pore size), ultrafiltration (0.5-2 nanometer pore size), electrodialysis, and reverse osmosis (<0.5 nanometer pore size).
Membrane technologies are now widely accepted as suitable processes for solids' separation from liquids, due to their high removal capacity and ability to meet multiple liquid/water quality objectives. Some advantages of this technology are effectiveness, easness to be automated, compact, removing pathogens, requiring less coagulating agents and disinfectors, simpler to maintain and capable of producing high-quality drinking water for human consumption. In addition to these advantages, membrane filtrations have some operation problems such as fouling and concentration polarization. The fouling can be a process where solute or particles such as clays, flocs (colloidal fouling), bacteria, fungi (biological fouling), oils, polyelectrolytes, humics (organic fouling) and mineral precipitates (scaling) deposit onto a membrane's surface or into membrane's pores that degrade the membrane's performance due to blocking of the membrane's pores. The fouling issue can be prevented or reduced by using acoustic pressure shock waves.
Industrial processes (petro-chemical, steel, chemical, etc.), oil/gas recovery, mining, and power generation use huge amounts of water that generate the so-called produced water. Produced water has a complex composition, but its constituents can be broadly classified into organic and inorganic compounds including dissolved and dispersed oils, grease, heavy metals, radio nuclides, organic matter, treating chemicals, formation solids, salts, dissolved gases, scale products, waxes, and micro-organisms.
The general objectives for operators treating produced water are: de-oiling (removal of dispersed oil and grease), desalination, removal of suspended particles and sand, removal of soluble organics, removal of dissolved gases, removal of naturally occurring radioactive materials, disinfection and softening (to remove excess water hardness). For removal of suspended particles, sand, soluble organics, dissolved gases, and radioactive materials usually there are used evaporation ponds, gas flotation systems, media filtration (sand, gravel, anthracite, walnut shell and others), ion exchange technology and chemical oxidation systems that use ozone, peroxide, permanganate, oxygen and chlorine.
Algae that live in water are a large and diverse group of simple organisms, ranging from unicellular to multicellular forms. Bloom concentrations of algae cause an increase in coagulant demand and treatability, taste and odor issues, filter blocking and toxin release in water treatment facilities. There are various strategies to control and remove algae from water such as dissolved air flotation, covering of basins and filters, advanced oxidation processes, ozonation, coagulation/flocculation by copper sulphate and potassium permanganate, bubble curtains, pulsed sludge blanket clarification, aeration, pre-oxidation using chlorine, ozoflotation, catalytic processes, barley straw, etc.
Water disinfection process is fundamental to remove microorganisms, and can be done by different methods such as use of ultraviolet, ozone and chemical substances (chlorine, hypochlorite, chloramines, chlorine dioxide, bromine).
Water hardness is known as existence of bivalent and trivalent cations such as calcium (Ca2+), magnesium (Mg2+), and in lower traces, aluminum (Al2+, Al3+) and iron (Fe2+, Fe3+). Water hardness causes some problems such as scale formation in pipes and cooling towers, reaction by soap and hard foam formation and decreased heat exchange capacity and membrane clogging. Conventional methods for hardness removal (also known as water softening process) are lime-soda process, ion exchange, electro-coagulation, electro-dialysis, reverse osmosis and nano-filtration.
In nuclear plants that use natural uranium as fuel, the reactors are functioning on heavy water, which is a form of water that contains a larger than normal amount of hydrogen isotope, deuterium. The heavy water used as a coolant for the nuclear reactors contains tritium (tritiated water) that can make it radioactive and hazardous for living organisms and environment. For this reason, nuclear power plants store the mixture of light water with tritiated water in drums for 10 times the half time for tritium (120 years) or this mixture is dispersed into environment in small quantities to prevent ecological disasters. An alternate method to separate heavy water (tritiated water) from light water (normal water) that is both economically and feasible is needed. In the patent application US 2005/0279129, different methods are presented (filtration, chemical, centrifugal, electromigrational and catalytic) that are currently used to separate heavy water (tritiated water) from light water. These methods have high complexity and are inefficient, expensive and can generate more contaminated materials (filters, membranes, etc.) that are contaminated and require storage or discharging problems as for the original water mixture. A combination of the principle presented in patent application US 2005/0279129 (lowering the temperature of the mixture to the melting point of the heavy water) combined with acoustic pressure shock waves, can offer an efficient method to accomplish an economic and feasible solution.
The sludge is a semi-solid slurry and can be produced from wastewater treatment processes or as a settled suspension obtained from conventional drinking water treatment and numerous other industrial processes. The term is also sometimes used as a generic term for solids separated from suspension in a liquid. Most producers pay for sludge disposal by weight, and water is heavy. Therefore, if the water is removed as much as possible, then the sludge is lighter and thus costs less to dispose it. Inorganic (lime and ferric salt) or organic (polymers) conditioners can be used in order to improve the solid content of waste sludge. Oily sludge frequently generated by oil production or processing sites, contains different concentrations of waste oil (40%-60%), wastewater (30%-90%) and mineral particles (5%-40%). The oil can be in its continuous phase although the water is in a high percentage in form of oil droplets absorbed onto solid particles, creating a protective layer and in the presence of surfactants forms emulsions, which creates difficulties in the waste treatment processes and subsequently in the dewatering process. The most common way to dewater sludge is to physically squeeze the water out of the sludge via pressure filtration dewatering, belt press dewatering filtration, air sludge drying processes, sludge dewatering centrifugation and vacuum filtration. In addition, a sludge drier can be utilized at the end of the process. Driers are oven like equipment that actually bake out the water. To improve of the process efficiency and reduce costs, other non-conventional approaches can be used such as acoustic pressure shock wave technology.
The water desalination technologies currently used are the reversed osmosis, multi stage flash, multiple effect distillation, vapor compression distillation and electro dialysis reversal. These technologies are energy intensive, which significantly increases the cost of produced desalinated water.
Reversed osmosis (RO) is a membrane separation process that recovers water from a saline solution pressurized to a point greater than the osmotic pressure of saline solution. In essence, membrane filters out salt ions from pressurized solution, allowing only water to pass. RO post-treatment includes removal of dissolved gasses (CO2) and pH stabilization via Ca or Na salts addition. It is interesting to note that RO works effectively only for low concentrated brine solutions, due to high concentrates that produce rapid scaling of RO membrane. The fouling/scaling of RO membranes significantly increases the operation cost. The membrane exchange represents the most of the cost necessary to operate a RO desalination facility therefore it limits the RO use in filtrating water from high concentrated brines produced by oil industry, mining or other industrial processes.
Thermal technologies—are employed in regions where the cost of energy is relatively low. Multi stage flash (MSF) distillation units are often coupled with steam or gas turbine power plants for better utilization of fuel energy. Steam produced at high temperature and pressure by fuel is expanded through turbine to produce electricity. The low to moderate temperature and pressure steam exiting the turbine is used to drive the desalination process. Multi effect distillation (MED) process involves application of sufficient energy that converts saline water to steam, which is condensed and recovered as pure water. To increase performance, each stage is run at a successively lower pressure. Even so, the energy consumption is significant and can be prohibitive in many cases.
Vapor compression distillation (VCD) uses vapor generated in evaporation chamber, compressed thermally or mechanically. The heat of condensation is returned to the evaporator and utilized as a heat source. Vapor compression processes are particularly useful for small to medium installations. However, VCD require energy intensive consumption to achieve desalination—a significant drawback.
Electrodialysis reversal (EDR) involves the separation of dissolved ions from water through ion exchange membranes. A series of ion exchange membranes is used, containing electrically charged functional sites arranged in an alternating mode between the anode and the cathode, to remove charge substances from the feed salty water. If the membrane is positively charged, only anions are allowed to pass through it. Similarly, negatively charged membranes allow only cations to pass through them. EDR uses periodic reversal of polarity to optimize its operation. The membranes of EDR units are subject to fouling, and thus some pretreatment of the feed water is usually necessary.
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