Grape Harvest Time Again

As I drive in to work this morning, I can’t help but notice the first picking crew I’ve seen this year.  I figure it must be Pinot Noir for sparkling wine, as it is still early for still wine varietals by all accounts I’ve heard so far.  Of course, being the engineer at heart that I am, this time of year makes me think of current and past clients and…how is their winery process wastewater system holding up.  Last year’s harvest was a big one and it sounds like this year promises to be large as well.   In addition to a shortage in tank space, all those extra grapes turn into more rinse-water and higher organic loads hitting the onsite wastewater system.  What type of process wastewater system and how it was sized and designed plays a large role in how well each system can accommodate these peak production years.

Many of the smaller wineries are on septic systems for their process waste disposal.  That’s right, septic systems just like at your house, except it’s like you dumped gallons of juice down your sink.  This adds a lot of organic matter which in turn results in a whole lot of bacteria growing inside the leachfield.  In some soil types, this can clog the soil and result in failure of the leachfield.  Fortunately for many of the small winery owners out there, harvest operations only occur for 30 to 60 days and are typically followed by a period of inactivity at the winery.  This, coupled with harvest beginning during the drier time of year in wine country, allows leachfields to be a viable option for most of the boutique wineries out there.

So, what if a winery doesn’t have soil for a septic system, or is too big to use a leachfield to disperse all of its process wastewater.  Well, these wineries are usually pushed into using either an aerated pond system or a packaged type treatment system.  Both of these options result in the treated process water tobe reused for irrigation onsite.  For a long time, many wineries were very against using their treated wastewater to irrigate their grapes because of what the consumer may think and what it may do to the soil over time.  However, as things are getting greener, many wineries are reconsidering this and see the treated wastewater as a valuable resource, which will help them save an even more valuable resource, their well water.  Also, as more wineries move toward the organic side of things, the concern for potential impacts on the grapes is lessoning as well.  After all, if you use it in the wine process which makes the wine your customers drink, why shouldn’t you water your vines with it?

Enough about where the water goes once its treated, what really interests me is how that water gets treated.  Most people have seen the big winery ponds with floating aerators in them.  When sized and designed right for the winery’s production volume, these ponds look like a simple irrigation pond, often containing ducks and other wildlife.  However, when these ponds are too small and are overloaded during harvest, they can end up as the stinky lagoon we in the industry know too well.  Oddly enough, the solution to fixing these stinky lagoons may lie in the alterative packaged treatment systems.

Packaged treatment systems are pre-engineered and constructed into shippable parts at a factory for assembly onsite by a local contractor.  Over the last 10 years numerous packaged treatment systems have emerged in the California wine industry as a space saving, effective method for treatment of process wastewater.  Some of these systems include AdvanTex by Orenco Systems, Inc., Lyve Winery Wastewater Systems, Hoot Systems, Vacuum Bubble Aerators, the Nibbler, and numerous others.  These systems primarily operate on an aerobic basis for removal of the organic matter in the wastewater.  Although each of these has successful winery installations, there has often been a learning curve to get to that point.  In my 10 years of designing winery process wastewater systems, I have identified three critical items for design of these systems; 1) Sizing, 2) pH control, and 3)Aeration.

Appropriate sizing of the treatment system is perhaps the most critical component.  A system that is too small will result in wastewater “flushing” though through the treatment system too fast which does not allow for biological breakdown or settling of the wastewater contents.  All wineries use different enology techniques and therefore water use can all across the board.  A treatment system which may be correct for one winery may not work for another winery of the same size because of the volume of water used at the two different sites.

As most winemakers know, and likely love to some extent, wine is very acidic.  It’s too bad that bacteria doesn’t have the same taste as winemaker.  Bacteria want wastewater to be as close to neutral pH as possible for optimum cell growth and efficient treatment.  Raising the pH can be accomplished with simple equipment, but must be accomplished at the beginning of any packaged treatment system for success.  Some wineries, because of cleaning caustics rinsed down the drain, will also need to add the ability to lower pH to stay within the desire bacteria growth range.  Low pH can kill an entire bacteria population in a treatment system, which is not very good in the middle of harvest, especially of there are strict regulatory discharge limits applied to that system.

Finally, no matter how well the basin for a treatment system is sized, if there is not sufficient oxygen to convert the organic material into bacteria cells,  the system is destined for failure.  The aforementioned stinky lagoon is a factor of poor aeration in the pond.  This is compounded in a packaged system because the volume for treatment is typically much smaller than that of a lagoon.  The volume of the treatment basin must be sufficient for contact with the oxygen imparted into the water by the aeration device.  Once dissolved oxygen levels drop to zero, it becomes an uphill battle to regain it, which typically doesn’t happen until harvest is over and high loads have stopped.

Well, I’m sure that I have bored many of you (if you even got this far), but for those of you that read through, I hope it was an interesting read.  If you too would like to “Geek out” on winery process wastewater, please feel free to give me a call.  to all those past and present winery clients out there, I wish you a trouble free harvest.

 

Ben Monroe – Project Manager at Always Engineering