Water Treatment Process For Agricultural & Animal Use Wells

Water Treatment Process

1. Water availability issues. For all of recorded time, crop growth and watering of livestock has depended on available rainfall, lakes, rivers, streams and natural reservoirs. All are classified as surface water. Some advanced societies diverted natural sources to locations where needed and soon thereafter hand dug wells tapped into shallow level aquifers. Water withdrawal was by bucket and rope. By the mid nineteenth century, hand pumps were available and soon after, windmills powered the pumps. It wasn’t until the 1950’s that reliable submersible electric pumps enabled large volume water withdrawal for irrigation and other applications. Too much of a good thing has forced ever lowering of ground water levels and dropping pump levels. Unfortunately, rain water has not been able to percolate through the ground to replenish the aquifer levels as quickly as it is being withdrawn so two things are happening – we are running out of available water and the quality is getting worse. Since 2014, the scientific community has been pursuing the possibility of there being as much as 3 times as much fresh water as there is sea water deep within the earth. Deep is an understatement because depth estimates range from 200 to 400 miles. The discovery and ongoing interest are based on seismic studies and our ever-increasing knowledge of tectonic plate physics. The water exists in a phase that is neither liquid, solid or vapor but in a 4th state (possibly as hydroxyl-OH) absorbed in a mineral called ringwoodite. This mineral is formed from magnesium silicate (Mg2SiO4) under high temperature and pressure. Sounds farfetched, but so did fracking for oil 30 years ago.
2. Number of agricultural wells in USA Latest (2018) USDA numbers are:
   1. 231,000 farms irrigated 56 million acres with 83.4 million acre-feet (27 trillion gallons) of water. This equates to 12,000,000 gallons per farm.
   2. Five states account for 50% of all agricultural wells
      1. California – 15%  35,000 farms
      2. Nebraska – 14%  32,000 farms
      3. Arkansas – 8%     18,000 farms
      4. Texas – 7%           16,000 farms
      5. Idaho – 6%           14,000 farms
3. Well water problems related to agriculture
   1. Crop production. 90% of problems are related to high Total Dissolved Solids (TDS) which is expressed as Parts Per Million (PPM). If a gallon of water were boiled until all wetness is gone and all that was left is typically a white to tan powder or scale, this Solid material would be everything from the periodic table of elements that were dissolved in the water. By weighing the Total of these solids and using arithmetic to determine their weight in a million pounds (120,000 gallons) of water. Distilled water has a TDS value of 0 and sea water is 32,000. Well water values are all over the range, but 350 PPM to 16,000 PPM are commonly found in agricultural well water tests. DS values above 750 PPM inhibit plants from freely up taking water from the soil and circulating it in the xylem system to deliver necessary nutrients. At higher levels and with certain chemical ratios such as that of sodium and calcium (SAR) can actually come close to stopping flow. The primary problem with high TDS is its directly proportional effect on the water’s surface tension which lowers its ability to climb in the plant due to capillary attraction. Also, there are often concentrations of one or two elements among the dozens or more in a particular well that inhibit growth or quality of a crop. State and/or county agricultural departments, working in concert with research universities, publish lists of water parameters for virtually all possible crops. One element in water that negatively affects both plants and animals is boron.
   2. Animal use. Unique to virtually all species of all farm animals is their ability to sense high TDS in the drinking water offered to them. Simply put, they will drink only enough to sustain life and will become dehydrated. Cattle and dairy farmers sell the weight of their product as a carcass or as a liquid both being over 90% water. Lower water intake and retention significantly reduces profitability. There are certain elements in water that are dangerous to animals that they do not sense.
      1. Sulfates. They act as a cathartic leading to diarrhea. Extreme fluid lost and rapid digestive transit time lowering nutrient uptake.
      2. Nitrates. Body changes nitrate to nitrite which lessens the blood’s ability to transport oxygen and leads to weakness and frailty.
      3. Insecticides, pesticides, fertilizers, etc. Neurotoxins causing difficult-to-diagnose behavioral and physical issues.
4. Current technologies for treatment of agricultural well water
   1. Reverse Osmosis (R.O.)
      This water treatment process has matured significantly since its inception in the 1960’s. In the last 10 years, changes in technology have been incremental, so the process is stable and results predictable. The technology revolves around a thin sheet of plastic material not unlike Saran Wrap through which water containing the dissolved elements discussed above. This material is referred to as a membrane and has the unique ability to pass water molecules and hold back or reject elements when the water/element combination is pressurized. The process is not 100% effective, so typical results are 70 to 99% removal of the dissolve elements based on element concentration (TDS), applied pressure, temperature, specific membrane chemistry and other equipment subtleties. The primary benefit of the RO is to lower the water surface tension to improve water transit through plant to deliver nutrients. Performance ranges are:
      1. Applied (pumping) pressures. 150 PSI at moderate TDS levels to 800 PSI at high TDS levels.
      2. Energy consumption. Using 35,000 gallons per day use of treated water and 65% recovery (35% of all water to drain) as a base line, electrical power required would be  5.7 kWh on the moderate TDS levels and 26 kWh for the high TDS levels
      3. Waste water. The rejected elements need to be carried away in a waste water stream that represents 25 to 50% of water delivered to the system. This water is almost always too bad to have any use.
      4. Equipment cost. CAPEX. Using the parameters from (2) above, the end user should expect to pay slightly over $100,000.00 installed on a prepared site and $300,000.00 for a high TDS system.
      5. Operating cost. OPEX. Plan on 5% annually of original purchase price PLUS cost of electricity over a 15-year effective system life for consumables, membrane cleaning and/or replacement, anti-scale chemicals, replacement parts, etc., etc.
   2. Ion exchange.
      This is a process dating to the late 1920’s where one to 3 contaminants such as nitrates, alkalinity, calcium, etc. can be removed from a well stream by substituting the offending element for chloride, sodium, hydrogen, hydroxide, etc. Although effective, there is a waste stream with chemicals that may percolate through the soil and contaminate the aquifer or it may need to be removed as hazmat.  Depending on the specific ion exchange (resin) used and its regenerating chemical, drain volume will run from 2 to 10% of total water requirement. The TDS reduction is minimal if at all so that there is seldom a measurable
      lowering of the surface tension.
   3. Absorption media holds on to contaminant, but adds nothing in exchange. Primary function is to remove selectively elements that are discarded. When media capacity is full, chemicals and/or backwashing take place or media is discarded. Classic uses are for iron, manganese, arsenic and boron. None reduce the TDS or the surface tension.
   4. Catalytic/magnetic and Magnetic.
      Both processes run a conductor (water) through a strong magnetic field. Faraday’s Law causes a voltage to be developed. This energy is known to lower the surface tension on many (but not all) high TDS water supplies. TDS is not reduced.
5. THE FUTURE
   Worldwide, water withdrawal from aquafers is estimated at 75 trillion gallons annually with replenishment at <2% from rainfall. Unfortunately, withdrawal in coastal areas is causing seawater intrusion that progressively makes the well water less acceptable and requiring even higher levels of treatment before use. There are no supportive numbers on the number of wells drying up, but it is happening. 8+ billion people on earth need to be fed but because of water scarcity many may die of starvation. We have established in this presentation that reverse osmosis is the go-to technology to obtain water with acceptable chemistry for plants and animals in spite of unrealistically high CAPEX and OPEX. Let’s pause for a moment and truly think of what is going on. Water containing only ½% by weight of minerals (5,000 PPM) is unsatisfactory for irrigation or animals, but the RO process uses energy-consuming pressures and expensive hardware to literally pull the 99-1/2% water away from the ½% minerals. Wouldn’t it make more sense to reach into unpressurized water and pull out the small weight of minerals? Basic arithmetic says this could reduce energy needs by as much as 99-1/2% and a high percentage reduction of hardware cost depending on the technology used. That technology is available as DIME IMPROVED CAPACITIVE DEIONIZATION (DICDI).

   Dime Improved Capacitive Deionization

   DICDI equipment involves the use of a relatively large volume of a custom adsorbent assembly (cell) immersed in unpressurized high TDS water. A low voltage, low amperage (low power) current flows through the water and adsorbent causing minerals in the water to cling into the adsorbent thus removed from the water and resulting in a significant reduction in TDS and surface tension. Power requirements are low enough to be handled by a small solar array. When the adsorbent becomes saturated with minerals, electrical polarity is reversed for a short time and adsorbed minerals are discharged into a low volume of water to drain. The DICDI adsorbent is made of 3 low-cost sustainable materials and processing involves 2 steps and some easy to fabricate, low-cost fixtures. Scaling from a system producing 500 gallons daily to 5,000 or 50,000 gallons is nothing more than increasing the number of adsorbent cells and increasing the support frame size. The DICDI process can reasonably expect to lower the ex-factory equipment cost by 75% and operating cost by 90% when compared to Reverse Osmosis. The systems are designed and constructed to improve well water quality for growing edible crops and to help animals thrive on the water they drink by treatment of water with a TDS range from 750 to 18,000 PPM. At this stage it not intended to treat 32,000 PPM sea water though future iterations may be adapted for this use.