Wineries and vineyards are increasingly concerned with the effects of their industry on the environment, and obviously, of the converse. Other than immediate individual responses to changing demands, though, there is little they can do to address the problem at the source. Rather, individual vineyards and wineries are contributing to global initiatives to reduce greenhouse emissions and to restore and protect the health of soil, water, and local ecosystems. These initiatives not only help the environment, but can save money, improve the product, and raise the reputation of the winery among consumers. We’ll focus here on efforts specifically related to the winemaking process.
The amount of water used in cleaning and maintenance operations should be a major focus for all wineries and may be one of the most effective and least expensive areas for reducing overall water usage. Wastewater produced in the winemaking and bottling process should also receive close attention, since this is when over 80% of annual wastewater is generated. However, finding and implementing solutions for vintage wastewater can be challenging, especially because contaminant concentrations and peak flows are at their maximum during the vintage stage.
Winery wastewater has a profile that makes it particularly challenging to treat effectively and economically. It’s full of inorganic salts, organic material, yeast, and bacteria, and yet the makeup of process water can vary substantially from season to season, from wastewater produced when pressing grapes to that produced later with washing and sanitizing equipment and bottling the finished product. For example, “high-strength” process water has more than 1 oz/gal of BOD (biological oxygen demand) and TSS (total suspended solids) of more than 0.4 oz/gal. These measurements require that wine wastewater be treated differently than wastewater from other food processing activities.
Start by Reducing
The three main principles of recycling, of course, are Reduce - Reuse - Recycle. The logical first step in managing water demand in a winery, then, is reducing use in the first place. Water use in a winery includes cleaning and washing operations during grape crushing and pressing, tank rinsing, barrel washing, bottling, residuals drainage, clean-in-place operations, filter washing, etc. These operations do not always occur simultaneously, so the volume and quality of the waste streams differ substantially.
There are typically several opportunities to increase water efficiency by careful monitoring of use, engaging employees in reaching water use goals, and making relatively simple improvements to the facility that make it easier to save water - even something as simple as installing hose shut off nozzles can make a difference during cleaning processes. A detailed use analysis will often suggest many ways water consumption can be minimized.
Managing Wastewater
After taking action to minimize the production of wastewater, wineries should examine which treatment process(es) are most appropriate for their situation. Because the characteristics of winery wastewater can vary so significantly over time, it may be necessary to consider separating the waste streams.
Treating Wastewater
There are several steps involved in treating wastewater, and for some uses not all steps will be necessary.
- Pretreatment and neutralization involve removing relatively large organic solids such as bits, lees and pomace, as well as inorganic solids such as perlite, bentonite clay, and diatomaceous earth. Filtering and screening are effective practices for this stage.
Whether the wastewater is to be discharged to the local sewer system or used to irrigate vineyards, the acidity must be controlled. The process of fermentation produces acidic waste, which can damage biological treatment systems, both at municipal treatment facilities and in the vineyard. Thoroughly mixing in mild alkaline solutions, such as lime, can bring wastewater within acceptable pH ranges, although some effluent may require stronger neutralization chemicals.
- During primary treatment, wastewater is typically moved to ponds or large tanks, where it stills. Since still water doesn’t have the energy to keep solids suspended, this stage allows even very small solids to settle to the bottom where they can be removed.
- Secondary treatment involves ridding wastewater of organic matter by employing aerobic bacteria to consume it and break it down into carbon dioxide, water, and
nutrient-rich biodegradable organic matter, which can be used as fertilizer. This stage of treatment produces much higher quality water with reduced BOD, TSS, and potentially disruptive nutrients like nitrogen and phosphorus.
In some cases, anaerobic process can also be used to break down organic matter. Initially, anaerobic bacteria break down complex organic compounds into short-chain volatile organic acids, which are used to create acetate and release hydrogen gas and carbon dioxide. Different anaerobic bacteria process the new molecules to generate methane gas and carbon dioxide, which can be used for fuel. This type of treatment takes longer than aerobic digestion and may produce odor issues but generates much less sludge. Typically, aerobic processes are preferred to anaerobic due to their speed, lack of offensive odors, and more effective nutrient removal.
- Advanced treatment refers to any process of wastewater treatment that removes greater amounts of contaminants, such as nutrients or metals, than primary or secondary treatments. The processes vary and may include physical or chemical processes, but the ultimate product exceeds the quality of secondary treatment, allowing the wastewater to meet requirements for specific uses.
Ponds and lagoons are cheap, easy to build, and take relatively less effort to operate than mechanical systems. There are two types of lagoons, aerobic and anaerobic, and treatment systems may involve one or both types. However, compared to operations at a municipal treatment facility, lagoons will typically produce a lower quality product, algae blooms may be an issue, and if regular maintenance is neglected, buildup of sludge can significantly reduce the pond’s storage capacity.
Since aerobic bacteria require oxygen to survive, aerobic lagoons usually need additional support during vintage in the form of aerators. Aside from providing oxygen, aerators allow dissolved gasses to be removed from solution and escape into the surrounding air.
When a treatment system calls for both anaerobic and aerobic treatment, lagoons or ponds can be constructed in sequence, with water entering the anaerobic pond first.
Geosynthetic liners should be used when constructing ponds or lagoons to prevent highly contaminated wastewater from seeping into the soil and the local water table. High levels of salts and organics in winery wastewater can sterilize the soil, degrade the quality of water pulled from wells, and damage aquatic ecosystems where it releases into surface waters.
In the case of anaerobic lagoons, where the biological process produces methane, floating covers should be employed to capture produced gasses, since methane represents one of the most powerful greenhouse gasses. Methane should be captured whether you intend to use it as a renewable power source or simply burn it off periodically. Covering anaerobic lagoons can also reduce or eliminate problems with offensive odors.
Constructed wetlands are more closely aligned with natural processes that purify water of all types. For wineries that have the land, it can be an excellent option for producing high quality water through a series of cells that closely mimic natural wetlands.
- As water flows into a wetland, it spreads out over a broad area and slows its movement. As the water’s energy drops, it drops suspended solids and trace minerals, which are filtered by the dense root systems of plants like cattails and bulrushes. In this first cell, waterproof geosynthetic liners are used on the sides and bottom of the cell to prevent leaks of untreated water and assure adequate water for the wetland plants.
In subsequent cells, the focus is on microbiological processes which break down nutrients and pollutants which are taken up by marginal and aquatic plants. A combination of UV exposure and plant secretions effectively kill any pathogens that are present. A typical wetland can filter primary (untreated) water to irrigation quality in 30 days without machinery or added chemicals.
