Abstract
Technological solutions allowing the increase of the technological efficiency of anaerobic methods of wastewater treatment are still under investigation. The weaknesses of these solutions can be limited by the use of active fillings. The aim of the present study was to determine the impact of fluidized active filling on the effectiveness of anaerobic treatment of sugar-industry effluent, the production efficiency and the qualitative composition of the biogas produced. High, comparable (p = 0.05) effluent treatment results were observed at tested organic load rates between 4.0 and 6.0 kg COD (Chemical Oxygen Demand)/m3·d. The COD removal rate reached over 74%, biogas yields ranged from 356 ± 25 to 427 ± 14 dm3/kg CODremoved and the average methane contents were approximately 70%. A significant decrease in effluent treatment efficiency and methane fermentation was observed after increasing the organic load rate to 8.0 kg COD/m3·d, which correlated with decreased pH and FOS/TAC (volatile organic acid and buffer capacity ratio) increased to 0.44 ± 0.2. The use of fluidized active filling led to phosphorus removal with an efficiency ranged from 64.4 ± 2.4 to 81.2 ± 8.2% depending on the stage. Low concentration of total suspended solids in the treated effluent was also observed.
Highlights
The chemical oxygen demand (COD) removal rate reached over 74%, biogas yields ranged from 356 ± 25 to 427 ± 14 dm3 /kg CODremoved and the average methane contents were approximately 70%
A significant decrease in effluent treatment efficiency and methane fermentation was observed after increasing the organic load rate to 8.0 kg COD/m3 ·d, which correlated with decreased pH and FOS/TAC increased to 0.44 ± 0.2
Fermentation reactors have been the preferred method for treating sugar-industry effluent, encompassing technologies such as anaerobic fixed bed (UAFB) [5], upflow anaerobic sludge blanket (UASB) [6], anaerobic downflow stationary fixed film (DSFF) [7], aerated fixed film (AFF) [8]
Summary
Sugar-industry effluent is characterized by a high load of suspended solids and nutrients and by a high COD (Chemical Oxygen Demand) mainly due to the presences of carbohydrates [1,2,3].Discharge of such effluent into the environment has a negative impact on aquatic ecosystems [4].As of recent years, fermentation reactors have been the preferred method for treating sugar-industry effluent, encompassing technologies such as anaerobic fixed bed (UAFB) [5], upflow anaerobic sludge blanket (UASB) [6], anaerobic downflow stationary fixed film (DSFF) [7], aerated fixed film (AFF) [8]and anaerobic batch reactors [9].Advantages of fermentation reactors include low operating costs [10,11], small size of the bioreactors not requiring large investment plots [12], low excess sludge, which can usually be used as a nitrogen- and phosphorus-rich fertilizer [13,14] provided high soil enzymes activity and greater stability in crop production [15], their capacity to treat highly-polluted wastewater and operating at high organic load rates (OLRs) [16]. Sugar-industry effluent is characterized by a high load of suspended solids and nutrients and by a high COD (Chemical Oxygen Demand) mainly due to the presences of carbohydrates [1,2,3]. Discharge of such effluent into the environment has a negative impact on aquatic ecosystems [4]. CH4 -rich biogas is an important product of anaerobic biodegradation of organic compounds [20]
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