**3.4 Seed germination bioassays**

Germination bioassays were performed following Fuentes *et al.* (2004), by using cress *Lepidium sativum L*. seeds, to evaluate the suitability of the treated wastewater in relation to crop irrigation and expressed as Germination Index. The treated wastewater and two dilutions in distilled water (25%, 50% v/v) were tested (Oliveira *et al*., 2009).

Winery Wastewater Treatment - Evaluation of the Air Micro-Bubble Bioreactor Performance 397

Fig. 12. 1st Racking at Quinta da Casa Boa

Fig. 13. Wastewater treatment system at Catapereiro

Fig. 14. Wastewater treatment system at Mingorra

Fig. 9. Global view at Mingorra winery

Fig. 10. Mingorra winery unit

Fig. 11. Vintage at Quinta da Casa Boa

Fig. 12. 1st Racking at Quinta da Casa Boa

Fig. 9. Global view at Mingorra winery

Fig. 10. Mingorra winery unit

Fig. 11. Vintage at Quinta da Casa Boa

Fig. 13. Wastewater treatment system at Catapereiro

Fig. 14. Wastewater treatment system at Mingorra

Winery Wastewater Treatment - Evaluation of the Air Micro-Bubble Bioreactor Performance 399

During the studying period, samples of winery wastewater were taken for laboratory characterization to evaluate their pollutant charge (Table 1). The values of pH ranged from 4 to 8, being this variation mostly dependent on the labor period. The electric conductivity of the wastewater showed no relevant variation in the different sampling periods and the

The highest values of COD were reached during the vintage period, followed by the first racking. These results are in accordance to those previously reported by other authors (Petruccioli *et al.*, 2002). As expected, the highest values of biodegradability (BOD5/COD) were achieved during the vintage period, due to the high concentration of simple molecules,

Concerning TS and TSS parameters, the results reveal a high variability during the vinification period. Moreover, the TS are significantly higher than TSS, which means that these wastewaters contain, mostly, dissolved organic pollutant charge. However, during 2nd racking the TSS concentration reach the maximum value derived from the presence of

Although polyphenols and anionic surfactants are important pollutants, it is not expected that they could influence the organic load, since they are present in low concentration. Nevertheless, after the wastewater treatment some compounds known as recalcitrant may remain in the treated effluent, such as the polyphenols that are responsible for colour and the residual COD, this can also be observed by the low biodegradability ratio presented in

Moreover, this type of wastewater has very low levels of nutrients that are essential to microbial growth. For this reason, it is often required the addition of nutrients to guarantee the process of cellular synthesis. Alternatively, it is possible to change some practices at the

The assessment of the water consumption is another key parameter for the successful of the winery wastewater treatment. In one of the monitored wineries the water consumption was evaluated throughout the operation period for two consecutive years. Internal management strategies were implemented to increase efficient water use, such as cleaning methods that aim the water reuse (closed-loop) pressure washing machines, among others. These simple

In this type of seasonal industry, the treatment system must be able to treat the wastewater produced in the vintage period. For this reason, many reactors have an appropriate volume for this stage but over dimensioned during the rest of the year. On the other hand, the high organic load of these wastewaters may promote the excessive growth of biomass, that requires an increase in the air supply (López-Palau *et al*., 2009) and creates problems of

The adopted strategy in this study is based on sludge reduction, as the production of excess sludge from the wastewater treatment plant is considered one of the serious problems encountered in the aerobic treatments (Liu & Tay, 2001). In this study, an aerobic step

range of registered values is not considered as inhibiting biomass growth.

easily metabolized (sugars and ethanol) by microorganisms (Duarte *et al.*, 2004).

tartrate. These solids are often problematic due to the high phenolic load adsorbed.

winery in order to balance this ratio (Oliveira & Duarte, 2010).

changes showed a saving in water consumption of about 40%.

alternated with an anoxic one was adopted as a strategy.

**4. Results and discussion 4.1 Wastewater assessment** 

Figure 17.

**4.2 AMBB treatment** 

sludge generation and disposal.

Fig. 15. The air micro-bubble bioreactor filled with clean water

Fig. 16. Flow diagram of the air micro-bubble bioreactor. 1- Bioreactor; 2- Settler; 3- *Venturi* injector; 4- Recirculation pump
