One- and Two-Stage Upflow Anaerobic Sludge-Bed Reactor Pretreatment of Winery Wastewater at 4–10°C

Abstract

The operating performance of a single and two (in series) laboratory upflow anaerobic sludge-bed (UASB) reactors (2.7-L working volume, recycle ratio varied from 1:1 to 1:18) treating diluted wine vinasse was investigated under psychrophilic conditions (4-10 degreesC). For a single UASB reactor seeded with granular sludge, the average organic loading rates (OLRs) applied were 4.7, 3.7, and 1.7 g of chemical oxygen demand (COD)/(L.d) (hydraulic retention times [HRTs] were about 1 d) at 9-11, 6 to 7, and 4 to 5 degreesC, respectively. The average total COD removal for preacidified vinasse wastewater was about 60% for all the temperature regimes tested. For two UASB reactors in series, the average total COD removal for treatment of non-preacidified wastewater exceeded 70% (the average OLRs for a whole system were 2.2, 1.8, and 1.3 g of COD/[L.d] under HRTs of 2 d at 10, 7, and 4 degreesC, respectively). In situ determinations of kinetic sludge characteristics (apparent Vm and Km) revealed the existence of substantial mass transfer limitations for the soluble substrates inside the reactor sludge bed. Therefore, application of higher recycle ratios is essential for enhancement of UASB pretreatment under psychrophilic conditions. The produced anaerobic effluents were shown to be efficiently posttreated aerobically: final effluent COD concentrations were about 0.1 g/L. Successful operation of the UASB reactors at quite low temperatures (4-10 degreesC) opens some perspectives for application of high-rate anaerobic pretreatment at ambient temperatures.

Fate of organic carbon in UAFB treating raw sewage: Impact of moderate to low temperature

“…The homoacetogenic bacteria seems less likely to exist in the reactor environment because the hydrogen concentration was much lower than can be reached by homoacetogenic bacteria (about 300 nM), which was also raised elsewhere (Xu et al, 2010). Previous studies of EGSB or UASB reactors revealed serious formation of acidifying sludge layer around the granules under psychrophilic conditions (Kalyuzhnyi et al, 2001). It was reported that under psychrophilic conditions, acidifiers have a high yield of 0.22 gCOD VSS g À1 COD removed (van Lier et al, 1997) owing to low starvation rate of acidifiers at low temperature.…”

Distillery spent wash: Treatment technologies and potential applications

“…In situ determinations of kinetic sludge characteristics (apparent Vm and Km) revealed the existence of substantial mass transfer limitations for the soluble substrates inside the reactor sludge bed. Therefore, application of higher recycle ratios is essential for enhancement of UASB pretreatment under psychrophilic conditions [55]. The conventional UASB reactors concept showed severe limitations mainly owing to problems related to mass transfer resistance or the appearance of concentration gradients inside the systems [56].…”

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.…”