Safely Dispose of Hydroponics Reservoir Water

The first step to responsibly taking care of your hydroponics water starts before you have wastewater.

I am expanding to a second location this spring.  The large concern became how to rid myself of the wastewater from my hydroponics-reservoir, as I do not have several acres of prairie grass to broadcast over.  After some passionate input, I thought that I might have to scrap the entire location.  Then fact checking.  Relief. This Article.

Why We Care

On a large scale the concern is that nitrates and phosphates will build up causing infertile soil at best; at worst polluting nearby water sources.  If too many nitrates and phosphates get into the water, it increases algae growth.  Algae is harmful to humans, and fish; as toxins from the algae build up in the muscle of both species.  The health ramifications are debatable, depending on what source you listen to.  However, no one wants to take the chance that they are -that asshole dumping wastewater in public drains; increasing blue-baby syndrome in the community.

Don’t Dump on Your City

I need to start off by stating that it is irresponsible to dump your wastewater into a drain that runs back to local water.  One of the reasons to grow hydroponically is water conservation.  Don’t void any benefit by dumping; nitrates, phosphates, and other chemicals, into city water.  City Water systems are closed systems, it causes problems after so many people dump these type of chemicals into the water system.  Yes, your water city system will not be damaged by you alone.  However, on a large scale filtering these chemicals is no easy chore.

Secondly, dumping wastewater into the city water is, completely avoidable.  Reservoir water still has nutrients that can be safely absorbed by plants.  The wastewater has the same chemical makeup, the plants not in your hydroponic system need.

Size Matters for Reasons

On a small scale, yes, you can just dump reservoir water on your grass or other plants.  Just make sure to dilute the solution first.  Federal criteria for phosphate that can be in a stream is .1 ppm.(4)  If you break down the composition of a 1,000 pounds of bermudagrass; there are 50 pounds of phosphates.(5)  Prairie grass does not take up quite as many nutrients.  However, I think the point is made (if you throw the water on grass, the grass will use the phosphates).   It takes pounds of nitrogen to fertilize an acre of grass.(5)  Nitrogen is considered a crop-limiter, so plants will use the small ppm in reservoir water.

For the system, Fire Blossom Farm has the ratio of fertilizer to food grown is approximately 3:2,000 pounds.  When a reservoir change is done, the estimated ppm is 600-1,000.  Drinking water is considered undrinkable at 500 ppm.  Diluting the wastewater down will never get it to drinkable levels, but it does get you down to levels that you can put on a plant without creating build-up . . . as long as you are taking some steps.

Some Steps

Use fertilizer meant for hydroponics systems.  This sound redundant if you’ve read other articles on this blog, but it’s worth saying again.  Use fertilizers meant for hydroponics.  Secondly, use fertilizers that have the lowest possible salt content.  You can always add Epsom salts in separately.  That worn out adage, It’s easier to add more than take it out., is true.

The fertilizer used by Fire Blossom Farm breaks down with UV exposure.  When broadcasted on plants do not hit the plant with the solution, water around the plant.  The plant will still be able to pull the nutrients and whatever chemicals are left on the surface too long will dissipate, or break down further.
Use an oxygenator.  Air stones add oxygen into the water.  Oxygen allows harmful chlorine to evaporate if you don’t filter your water.  Nitrogen does not stay in solution long.  If Nitrogen is bombarded with oxygen it will return to its gaseous form quicker.  Also, oxygenated water promotes plant growth.

How Not To Make it Worse

Do not use more nutrients than you need period, period  If your plants are eating most of the nutrients in the water; there will be less chemical in the wastewater.  Secondly, do not use a water softener even if you can help it.  Most water softeners use sodium ions.  Sodium can build up in a plant to toxic levels quickly.  There are a few water softeners that use potassium ions.   So if you are trying to grow a plant that can not process the chemicals in your hard water use a softener that does use potassium ions.  The levels of potassium a plant can use without becoming toxic is much higher; as plants require a higher level of potassium. Better yet use rainwater whenever you can.  Adjust your nutrient formula accordingly.

If You Are Seriously Large Scale

Algae that is not toxic to humans is being studied as a possible solution to removing harmful elements from water.(1)  I only suggest this a starting point for those growing on a commercial scale.  The only reason I know this is a study that did take place at Arizona State University is because I knew the person directly.  He suggested the solution already existed, but the algae needed to be contained.  He took the contaminated water, grew the algae, and then composted the algae as a fertilizer with other biodegradables.  How successful this study was, I cannot attest to.  However, Researchers at Rochester Institute of Technology stumbled onto a similar idea, but with the byproduct of producing biofuel.(3)  So this is a viable option that does deserve more research.

If You’re Still Reading and Care

I have been over diluting the solution from the location on Barrett.  I can safely distribute ‘wastewater’ to plants by diluting it on the Freedom location too.  We generally clear the reservoirs out only once a year in the fall.  A batch of winter kale will be grown at this location, for that purpose.

Sources
  • Carruthers, Steven. “Issue 18: Nutrient Scrubbers.” Hydroponics & Greenhouses. N.p., Oct. 1994. Web. Explores the possibility of using algae as a solution to hydroponics wastewater. 
  • We Grow Hydroponics. “Grower’s Guide, 2013.” 2013 ed. Simi Valley: Http://wegrowhydro.com, 2013. Print. A small booklet that explains the variable and components of hydroponics. 
  • Squatriglia, Chuck. “Using Algae to Clean Wastewater, Make Fuel.” Wired. Conde Nast, n.d. Web. 01 Dec. 2016. Article on Rochester Institute of Technology’s, an experiment about purifying water with algae. 
  • Kotoski, James E. “Black Earth Creek & Limnology; Mini Facts & Analysis.” Spring Harbor Environmental Magnet Middle Scho. Spring Harbor. Lecture. Lecture sheet for middle school. Pretty pictures and federal standard for acceptable levels of phosphorus in water. Arnall, Brian, Travis Hanks, James Jones, Joshua Payne, Chad Penn, Brian Pugh, Darren Redfearn, Chris Rice, Jason Warren, and Hailin Zhang. Oklahoma Forage and Pasture Fertility Guide Oklahoma Forage and Pa. N.p.: Oklahoma Cooperative Extension Service Division of Agricultural Sciences and Natural Resources Oklahoma State U, n.d. Print. A study of grasses and their nutrient requirements; with the intent, of assisting ranchers produce feed.

 

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