Guidelines for the management of winery wastewaters

Winery Wastewaters (WW) are characterised by their high biological oxygen demand, organic contents and electrical conductivity, being regarded as one of the major environmental issues generated by wine production. Each winery is unique in WW generation (highly variable, 0,5-14 L per litre of wine) and disposal. Thus plans for environmentally friendly management of waste are not universal and should be tested for their effectiveness. In Portugal, many wineries discharge directly their WW into the surface water bodies, sewage or irrigation, without planning. With careful planning and management, the use of WW in agriculture can be beneficial to the environment, contributing to recycle nutrients and saving water. The sustainable development of landscape, and agricultural irrigation with WW, should be done using guidelines, which are an important step in the planning and implementation of safe use of WW for irrigation. These guidelines are established in some wine-producing countries with high environmental concern, especially Australia and South Africa. However, it is important to know the quantitative and qualitative characteristics of the winery WW, the potential phytotoxicity associated with this type of WW and the edaphoclimatic conditions of the vitiviniculture region, in order to create / adapt guidelines that are in compliance with Portuguese legal requirements. The winery wastewaters (WW) are seasonally produced and its treatment and disposal represents a main problem to the winery sector, as a result of the amount and composition of the wastewater produced over the year. WW is generated mainly as the result of washing equipment and bottles and purges from the cooling process. As a consequence of the working period and the winemaking technologies, volumes and pollution loads greatly vary over the year (Duarte et al., 2004; Eusébio et al., 2005). Further, as each winery is unique in wastewater generation (highly variable, 0,5 to 14 L per litre of wine) and disposal, plans for environmentally friendly management of waste are not universal and should be tested for its effectiveness. In Portugal, many wineries discharge their wastewater directly into surface water bodies, only 17% of the wineries have environmental licence, 5% dispose a pre-treated wastewater for the municipal wastewater treatment and 7% dispose the treated wastewater into water body (MAOTDR, 2007). In order to achieve the best available technology for wastewater treatment is also important to be acquainted with the wastewater final disposal. In Portugal, the sector with the highest water consumption is the agricultural sector (87%), followed by urban sector (8%) and finally the industrial sector (5%) (MAOTDR, 2001). The search for new water sources is based on different driving forces, in particular, the population growing and the increasing interest in treated wastewater as a source of supplemental irrigation (Ryder et al., 2004). In water scarce regions, there is a benefit when the treated wastewater is used as an economic additional water supply, in agriculture (WHO, 2006), which occurs in southern Portugal. Therefore, a number of concerns had to be taken into account and the knowledge of the treated wastewater composition is critical for safe use (Bustamante et al. 2004). Another important issue is the appropriate price for wastewater. According to Mekala et al. (2008) a very low price for wastewater may encourage inefficient use and may lead to the perception that it is a cheap and unlimited resource. This problem should be considered in Portugal, since the efficiency of water use in the agriculture sector is already very low (57%) (MAOTDR, 2001). However, with regard to the wine sector, the vineyards are usually in the surroundings of the cellar, so the cost of the winery wastewater treatment is charged to the producer. The experience gained over several years in research projects, where different wineries were monitored, contributed to the improvement of technical and scientific knowledge in this area. In this study, a diagnostic was made in several wineries, throughout the country, which were characterized in terms of type of wine produced; tonnes of grapes processed; water consumption, WW quality and