Since the wine produced by the fermentation process is safe to drink, many people unfamiliar with wine making assume all wastewater produced is also relatively safe. Unfortunately, there’s a few specific features common to most, winery, wastewater mixtures that make them hazardous to the environment. Even when the wastewater is diluted enough for direct reuse, it can create odor issues that make neighboring residents and businesses unhappy. While this water isn’t hazardous, and therefore is free from federal regulation from the Environmental Protection Agency in most areas, it’s still considered waste and is regulated at the state and local level. Discover what makes winery wastewater so challenging to handle, whether it’s generated during the cleaning process or as runoff from irrigating fields of grapevines.
Acidity and Organic Chemicals
Since spilled and residual wine makes its way into almost all of the wastewater produced by a winery facility, the liquid is generally low on the pH scale and therefore acidic. The natural residues of the plant stems and skins are also high in nitrogen, making wastewater a potent fertilizer. This can benefit fields when the water is reused as irrigation supply, but it can threaten waterways with oxygen depleting blooms if released or leaked. Organic chemicals, like high sugar levels, also cause algae and slime blooms in open waters. Even the purest process water and wastewater will contain these ingredients that need treatment before the water is reused or released into the environment.
Process water generally comes from washing and sanitizing the various tanks, crushing equipment, filters, mixers, sampling and testing units, and the general facilities. This means that it may contain faint to strong traces of cleaning products that are damaging to soil or water if released directly. Aeration and other processing treatments often struggle to reduce levels of sodium in particular, leaving salinity high in soil that’s watered regularly with this reused water. Switching to low sodium cleaning products, including potassium-based mixtures, can reduce the salinity and chemical load without extensive processing.
BOD and TDS/TSS
Total dissolved solids (TDS) and total suspended solids (TSS) are generally high in winery wastewater; especially during the crush season. Crushed grapes leave behind a pulp of skins, seeds, and stems known as pomace. Pomace is mixed in with the wastewater as equipment and tanks are rinsed off. This type of solids and sediment is specifically known as biochemical oxygen demand (BOD) because it’s measured by the oxygen needed to break it down via microbial activity. BOD in winery wastewater is highest during crushing, followed by the filtration periods. Even during the rest of the year, wastewater is often high in TDS and TSS from wine spills that are still rich in sediment. Rinsing off the filters used to remove sediment and dead yeast cells, from the fermenting wine, also leaves a high level of solids mixed in with the water. Aeration works well to reduce both TDS and TSS over time, but filtration may be necessary first during crushing season.
Volume and Surge
Wastewater generated by a winery varies in volume from month to month as the amount of processing fluctuates. During active crushing and wine making stages, a winery can generate thousands to hundreds of thousands of gallons of wastewater all at once. Surge events can release thousands of gallons per hour as large equipment is sanitized and cleaned between batches. It’s not always easy to calculate volume and surges because a bumper crop can leave a winery crew with more cleaning runoff than expected. Careful calculations will prevent both internal surges of wastewater, and external flooding, from overwhelming the capacity of the storage ponds.
Odor is one of the biggest complaints about winery wastewater ponds, whether they’re designed for on-site processing or just temporary storage. Wineries built in suburban and urban areas are particularly likely to generate complaints due to the smell, but even rural facilities can release long-reaching odors. The smell is generated by the microbes breaking down the waste products mixed into the water, but aeration or a surface cover can control the problem. If a winery is very close to homes or businesses, a septic tank or bioreactor may be a better choice than a large and open pond. Odor is a natural and expected part of wastewater processing or storage, but there are plenty of ways to control and prevent it.
Soil and Water Damage
Due to the sugar, pH level, and high levels of dissolved organic material, winery wastewater can damage both soil and water when released at concentrated levels. However, water that’s more diluted, and free from strong cleaning chemicals, is often ready to reuse directly on soil without any long-term damage; like salination. It all depends on the quality of the water and parameters of the soil. Open bodies of water, like rivers and lakes, are more sensitive to waste water releases. If you must release water before it’s fully processed, soil is generally a better choice. Grapes can typically handle all the effects of fairly concentrated wastewater as long as it’s minimally processed with adequate time in a processing pond.
Insect and Animal Attraction
The smell of fermentation, and sugars, can attract both animals and insects to the wastewater. This is especially likely when storing the water without processing. Processing ponds are less attractive to wildlife, but they can breakdown if animals do fall in and clog filters or break pumps. Covers often go a long way in controlling unwanted access from wildlife and humans alike. If it’s necessary to leave the ponds exposed for evaporation and aerobic digestion, fencing and netting over the surface may help instead. Adding insecticide to the water may be a necessary step in processing to control infestations.
High Energy Consumption
High energy consumption patterns in the industry are driven by heating, pumping, and processing water for winery cleaning. Without proper heating, it’s hard to get sticky, sugary residues off of the equipment and impossible to properly sanitize tanks. While it’s almost impossible to eliminate the need to heat water, it is feasible to reduce energy use during processing for wastewater you plan to reuse. Efficient pumps and aeration units trim down energy costs to improve the winery’s bottom. If you’re concerned about affording water treatment systems, considering investing a little more up front for the best equipment. This initial investment can pay off in the long run with reduced energy demands.
Dredging for Sludge Control
Even with advanced filtration and settling processes, to accumulate sediment at the bottom of the pond, it’s necessary to routine dredge all tanks and ponds used for processing winery wastewater. Short term holding ponds and tanks usually need dredging less often, but they’ll still eventually need cleaning to maintain the intended volume. Dredging is a costly and time-consuming process that is best completed when the pond is drained between uses. If you don’t drain your ponds completely at any time because they’re also used for retention, it will be a harder process. Make every effort to reduce sediment and solids in the wastewater before it reaches the pond to extend the time before dredging is needed again.
Proximity to Homes and Businesses
Finally, the proximity of many homes and businesses to wineries puts them at risk for more than just some unpleasant smells. Storing a large amount of any liquid, including wastewater, creates a flooding hazard if the system fails. Secondary containment measures, like basins and lined berms, prevent leaks and spills from threatening nearby homes and businesses. They’re also recommended to protect the winery itself from damage, if there’s flooding, even if there are no neighbors nearby.
Despite all these negative aspects of winery wastewater, it’s actually quite a positive byproduct for many facilities. Effective processing methods are the key factor in whether wastewater is valuable or frustrating for the company. When designing new storage and processing for your winery, start with the right liner to make sure not a drop of wastewater is truly wasted. You will find all the liners you need, for your wastewater holding ponds of any size or style, here at BTL Liners.