**2.3 Diagnosis process**

392 Mass Transfer - Advanced Aspects

system; bioreactor type and its mechanical design; the composition of the fermentation

The mass balance for the dissolved oxygen in the well-mixed liquid phase can be established

Where dC/dt is the accumulation oxygen rate in the liquid phase, OTR is the oxygen transfer rate from the gas to the liquid phase, described by equation (1) and OUR is the oxygen uptake rate by microorganisms. The methods that can be applied for the oxygen transfer rate measures can be classified depending on whether the measurement is done in the absence of microorganisms or with dead cells or in the presence of biomass that consumes oxygen at the time of measurement. When biochemical reactions do not take

The dynamic method used to measure the kLa value is based on the dissolved oxygen consumption and supply. In this method the change in the dissolved oxygen concentration is analyzed supplying air until the oxygen saturation concentration in the liquid phase is reached. The oxygen decreasing is then recorded as a function of time. Under these conditions the equation (2) can be expressed as equation (4), but, after the decreasing phase, the oxygen is again supplied and the equation (2) can be written as equation (5). In these

Furthermore kLa is usually expressed at standard conditions of temperature and pressure,

The determination of the oxygen uptake rate OUR can also be carried out using a dynamic method which measures the respiratory activity of microorganisms that grow in the bioreactor. When the air supply is switching off, the dissolved oxygen concentration will decrease at a rate equal to oxygen consumption due to the microorganisms respiration rate. In this situation the OUR is determined from the slope of the plot of dissolved oxygen concentration *vs* time. The biomass concentration should be known in order to determined

Another important parameter in the aerobic reactors optimization is the sludge settling and production. The large amount of excess sludge generated during activated sludge process is estimated to cost about 40-60 % of the operating cost (Chen *et al*., 2001). This sludge contains volatile solids and retains about 95% of water resulting in a large volume of residual solids produced. The biological sludge production in conventional wastewater treatment plants

݀ݐ ൌ ܱܴܶ െ ܱܷܴ (2)

݀ݐ ൌ ݇ܽ ൈ <sup>ሺ</sup>כܥ െ ܥሻ (3)

൰ ൌ െ݇ܽൈݐ) 4(

כܥ൰ ൌ െ݇ܽൈݐ) 5(

݇ܽଶ ൌ ்݇ܽ ൈ ͳǤͲʹͶଶି் (6)

broth and the possible effect of the microorganisms (Xu *et al*., 2010).

ܥ݀

as (Garcia-Ochoa & Gomez, 2009; Irizar *et al*., 2009):

place, OUR=0, then the equation (2) can be simplified to:

ܥ݀

cases the kLa values can be determined from the slope of the *ln f(CL) vs* time.

ܥ൬ ݈݊ ܥ

݈݊ ൬ͳ െ ܥ

20ºC, 1atm (equation 6).

the specific oxygen uptake rate (SOUR).

The selection of the most appropriate technology for the winery wastewater treatment is a difficult step that should be done after a diagnosis process. A proper diagnosis should conduct a survey report that includes all the information required for decision-makers. Regarding the production process, it should address all activities associated with it: vintage, racking and bottling (Figure 6). The knowledge of materials and supplies, as well as byproducts generated during the process is essential in diagnosis. The water uses and water consumption are critical, both in terms of quantity or quality. The survey of sewers in the farm unit, particularly if the drainage system is separated or combined, and the points of wastewater discharge should also be covered. The wastewater flows should be evaluated through the installation of flow meters. The different streams of wastewater generated must be quantified in order to make an assessment, as rigorous as possible.

The water consumption in two Portuguese wineries, one small and one medium size are quite different, with regard to quantity. However, the distribution of water consumption has a similar behavior throughout the year (Figure 7 and Figure 8). The data presented show that most water (60%-80%) is consumed in the vintage period that last about a month. So, the collection of water consumption associated with the physicochemical characterization of the wastewater is essential for the proper sizing of any treatment system. In addition, it is

Winery Wastewater Treatment - Evaluation of the Air Micro-Bubble Bioreactor Performance 395

microorganisms. Thus, this separation reduces the costs of wastewater treatment and

The winery wastewater was collected, during four years, from three wineries of different sizes and characteristics and located in different Regions of Portugal. The Casa Agrícola Quinta da Casa Boa, located at Runa, Lisboa Region, producing only red wines, has a small/medium dimension with a production capacity of 200,000 L. The Catapereiro, located at Alcochete, Tejo Region, produces both white and red wines, has a medium dimension with a production capacity of 1 000,000 L of wine. The Herdade da Mingorra, located at Beja, Alentejo Region, has a medium dimension with a production capacity of 1 000,000 L of wine

Composite samples of the winery wastewater, representative of each phase of the process, were taken and maintained at 4ºC. A set of major key parameters were defined and analysed, according to *Standard Methods for the Examination of Water and Wastewater* (1998), in order to assess the winery wastewater pollutant charge: pH, conductivity, chemical oxygen demand (COD), biochemical oxygen demand (BOD), total suspended solids (TSS), volatile suspended solids (VSS), polyphenols, anionic surfactants, Na, K, Mg and Ca. The winery wastewater flows were evaluated from water consumption. With this propose the wineries

The Air Micro-Bubble Bioreactor (AMBB) with a total volume of 15 dm3 consists of a cylindrical bioreactor, equipped with a circulated pump and a settler (Figure 15). The aeration was conducted during the wastewater recirculation by a high efficiency Venturi injector (HEVI) in conjunction with mass transfer multiplier nozzles (MTM). The MTM nozzles discharge the air/water mixture from the HEVI into the bottom of the bioreactor (Figure 14). The AMBB is equipped with an air flow meter and a monitoring probe (HANNA Instruments) able to on-line monitor pH, DO and temperature. Figure 16 shows a

Several trails performed with the AMBB, under batch conditions were carried out during 15 days. The reactor was inoculated with 15 dm3 of fresh winery wastewater, from the vintage period and with 0.15 dm3 of acclimated biomass, obtained during the treatment of winery wastewater, in the previously year. Samples from the mixed liquor were daily taken for physico-chemical characterisation. The aerated flow was 2 dm3 min-1. The operating temperature was 20-30ºC. The recirculation of the mixed liquor started with 20 min hour-1,

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

**3. Winery wastewater treatment in the Air Micro-Bubble Bioreactor** 

monitoring, which are associated with the disinfection process.

installed general water counters to be daily read and register.

**3.1 Wastewater characterization** 

(Figure 9 to Figure 14).

**3.2 Bioreactor set-up** 

schematic overview of the bioreactor.

**3.4 Seed germination bioassays** 

**3.3 Bioreactor start-up and operating conditions** 

with a flow of 40 dm3 min-1 and then was changed to 5 min hour-1.

dilutions in distilled water (25%, 50% v/v) were tested (Oliveira *et al*., 2009).

possible to understand the need for flexibility of the treatment system, because the system should allow good removal yields, during the vintage period, but has also to remain in operation during the rest of the year even at low loads. In small wineries often there is a minor stream of wastewater during several months, which may lead to bioreactor inefficient performance. To overcome this situation a feast/famine strategy may be a challenge for future research at a full-scale.

Adapted from Duarte *et al*. (2004).

Fig. 7. Distribution of water consumption during the global period of processing at a medium dimension winery

Fig. 8. Distribution of water consumption during the global period of processing at a small dimension winery

The physicochemical characterization assessment is carried out by determining specific parameters such as pH, electrical conductivity, dissolved oxygen, chemical oxygen demand, biochemical oxygen demand, total phosphorus, total nitrogen, total solids, suspended solids, total polyphenol compounds, anionic surfactants. In order to evaluate the fate of treated wastewater, it is also important to know the winery surroundings, in particular the existence of a sewage, the irrigation area, the type of structures and available areas, among others.

In wineries that intend to reuse the treated wastewater for irrigation, other concerns should be considered. The domestic wastewater flow containing high concentration of pathogenic microorganisms should not be mixed with the industrial wastewater stream. This flow should be treated separately or discharged in the sewage. This decision is extremely important, since the wastewater from winery operations does not contain pathogenic microorganisms. Thus, this separation reduces the costs of wastewater treatment and monitoring, which are associated with the disinfection process.
