Treatment of winery wastewaters in a membrane submerged bioreactor

Abstract

Wine production is seasonal, and thus the wastewater flow and its chemical oxygen demand (COD) concentrations greatly vary during the vintage and non-vintage periods, as well as being dependant on the winemaking technologies used, e.g. red, white or special wines production. Due to this seasonal high variability in terms of organic matter load, the use of membrane biological reactors (MBR) could be suitable for the treatment of such wastewaters. MBR offers several benefits, such as rapid start up, good effluent quality, low footprint area, absence of voluminous secondary settler and its operation is not affected by the settling properties of the sludge. A pilot scale hollow fibre MBR system of 220 L was fed by adequately diluting white wine with tap water, simulating wastewaters generated in wineries. The COD in the influent ranged between 1,000 and 4,000 mg/L. In less than 10 days after the start up, the system showed a good COD removal efficiency. The COD elimination percentage was always higher than 97% regardless of the organic loading rate (OLR) applied (0.5-2.2 kg COD/m3 d), with COD concentrations in the effluent ranging between 20 and 100 mg/L. Although the biomass concentration in the reactor increased from 0.5 to 8.6 g VSS/L, the suspended solids concentration in the effluent was negligible. Apparent biomass yield was estimated in 0.14 g VSS/g COD.

Anaerobic treatment of winery wastewater in fixed bed reactors

“…The feed was made alkaline with the addition of NaOH (0.5-1.0 ml 10 N NaOH/l feed), and was supplemented with nutrients corresponding to a COD/N/P ratio of 400/7/1 [9]. Due to the low nutrient content present in winery wastewater, the addition of nitrogen and phosphate sources is recommended for cellular growth in the biological treatment process [14,16,31] to maintain a minimum COD:Tot N:P ratio of 400:7:1. The main characteristics of the feed are given in Table 2.…”

“…For the conventional activated sludge systems [8,9] and SBR systems [10] operated with an OLR less than 1 kg COD/m 3 day, COD removal efficiency of above 90% was achieved. Recently several advanced aerobic treatment systems were developed such as jet-loop reactors [12], moving bed biofilm reactors [14], FBBR [15] and MBR systems [16]. These systems are also capable of achieving COD removal efficiency above 90%, but at relatively higher loading rates.…”

“…Based on aerobic systems are conventional activated sludge systems [8,9], SBR systems [10,11], jet-loop reactors [6,12], aerobic biofilm systems such as RBC [13] and more recently advanced treatment systems such as moving bed biofilm reactors [14], fixed bed biofilm reactors (FBBR) [15] and membrane bioreactor (MBR) systems [16]. Based on anaerobic systems are anaerobic filters [17], UASB [18,19], hybrid reactors [20] and anaerobic SBR [21].…”

“…The use of conventional activated sludge systems is sometimes problematic due to bad settling properties of the sludge caused by the development of filamentous bacteria or the formation of dispersed flocs, resulting in an effluent with a high solids concentration and turbidity [16]. Aerobic biofilm systems such as FBBR are an alternative to the conventional activated sludge plants as these systems offer advantages such as low reactor volume requirements; reduction of bulking problems; the absence of return flow and backwashing due to the high void ratio of the filling media and an easier management with respect to the conventional activated sludge plants [15].…”

“…Compared to aerobic processes, anaerobic process do not require oxygen and therefore are less energy intensive and sludge production is much less making the process simpler and cheaper [16,22].…”