Fate and Affect of Physical Solids contained in Raw Influent Winery Wastewater 

While the organic concentrations of Winery Waste are different than those that are found in normal Domestic Waste, the basic classifications of these constituents are the same. For the purposes of wastewater treatment, the main classifications are Bio-Chemical Oxygen Demand (BOD) and Total Suspended Solids (TSS).  These two classifications are utilized conjunctively to not only measure the strength of the raw waste, but also to measure the efficiency of the treatment process by analyzing BOD and TSS in the treatment plant discharge (Effluent).  These two constituents are also normally listed in Waste Discharge Requirements (WDR’s) by the State Regional Water Quality Control Board as standards for discharge of the effluent.

The basic breakdown for BOD and TSS in the winery waste is as follows;

1. BOD – The liquid portion of the waste stream that includes dissolved organics from the grapes and process waters, termed “dissolved BOD” and finely divided organic suspended solids, termed “particulate BOD”.  Together these are termed “Total BOD”

2. TSS -  The solids portion of the waste stream that includes fine suspended solids and “gross solids” which includes the grape skins and other process debris.

The treatment methodology utilized for the reduction of BOD and TSS in this winery waste is a form of the “Activated Sludge Process”.  Very basically, this is an Aerobic Process that develops a “floc” (activated sludge) to absorb and oxidize (reduce) the concentration of BOD.  In addition the floc will absorb certain size and types of TSS for oxidation/reduction.  This particulate BOD is more difficult to oxidize than the dissolved BOD.  In addition, the larger particulate solids (TSS) become imbedded in the floc and cause settleability problems. Settleability problems cause high TSS concentrations in the discharged effluent.  This, of course, causes violations of the discharge requirements.

For the above reasons, it is important to remove as much of the TSS (grape skins) from the influent as possible, prior to the activated sludge process. This greatly lessens the loading on the entire treatment system and makes for a more stable process.  It also reduces the potential for incurred effluent violations.

The removal of the grape skins can easily be accomplished by “mechanical means”, that is, by flowing the influent stream through a “rotating screening” system sized properly for the design flow and concentration of grape skins.