biological leachate treatment: suspended growth
BIOLOGICAL LEACHATE TREATMENT: SUSPENDED GROWTH ACTIVATED SLUDGE VS. AEROBIC GRANULAR SLUDGE Y. REN*, Q. YUAN* AND F. FERRAZ** * Dep. Of Civil Engineering, Univ. of Manitoba, Winnipeg, MB Canada ** Dep. Of Hydraulics and Sanitation, Univ. of Sao Paulo, Sao Carlos-SP, Brazil
SUMMARY: Landfill leachate treatment was investigated using two anaerobic/aerobic sequencing batch reactors (SBR) inoculated with suspended growth activated sludge (ASBR) and aerobic granular sludge (GSBR). The total ammonium nitrogen (TAN) concentration in the GSBR influent was as high as 1200 mgN/L with an average TAN removal efficiency of 99.7%. However, the ASBR treatment did not show a consistent performance in TAN removal. In GSBR, nitrification was partially inhibited at FA concentration from 48 to 57 mgN/L, which was two times more than the FA concentration that inhibited nitrification in ASBR. The low chemical oxygen demand (COD) removal efficiencies of GSBR and ASBR were associated with the refractory organic content of the leachate used in this study. The results prove that aerobic granular sludge is a robust method as compared to suspended activated sludge to treat leachate containing high levels of TAN and FA.
1. INTRODUCTION Leachate is a collection of wastewater generated in landfills due to the precipitation through municipal solid wastes, the liquid produced by biochemical processes in landfill cells, and the water constituent of the wastes (Renou et al. 2008). The composition of leachate is dependent on several factors, including temperature, precipitation, the composition of landfill waste, and the age of landfills. However, the main constituents of leachate include heavy metals, xenobiotic compounds, high concentrations of ammonium nitrogen, and biodegradable and refractory organic matter (Renou et al. 2008). Several alternative methods have been considered to treat leachate. Conventional activated sludge processes have been extensively applied to treat leachate or mixtures of leachate and domestic wastewater. Aerobic granular sludge (AGS) can be considered as a valuable alternative to biological treatment of leachate due to its peculiar characteristics. The AGS method presents unique characteristics, including high settling velocity, compact structure, simultaneous nutrient removal capability, and ability to sustain high biomass concentration (Adav et al., 2008). However, there has not been any major publications about leachate treatment by AGSR. An important contribution was provided by Wei et al. (2012), who used an SBR to develop AGS for leachate treatment. Their results indicated close to 83% of COD removal and nitrogen removal varied from 44% to 92% depending on the influent ammonia concentrations. Considering the advantages of AGS presented above and the lack of studies supporting AGS application in leachate treatment, this study aimed to compare the performance of AS and AGS in biological leachate treatment. Proceedings Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium/ 2 - 6 October 2017 S. Margherita di Pula, Cagliari, Italy / © 2017 by CISA Publisher, Italy
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
2. MATERIALS AND METHODS 2.1 Experimental setup Two lab-scale SBRs namely suspended activated sludge SBR (ASBR) and aerobic granular sludge SBR (GSBR) were inoculated with activated sludge collected from South End Water Pollution Control Centre (SEWPCC) in Winnipeg, Manitoba, Canada. The ASBR was operated at 3 cycles per day. Each cycle consisted of a 10-min feeding period, 1.5-hour anoxic/anaerobic period, 5.5 hours of aerobic (react), 40 minutes of settling, and 12 minutes of decanting. The solid retention time (SRT) in ASBR was set at 10 to 40 days. The GSBR was operated at 3 cycles per day. Each cycle consisted of 0.5-hour feeding period, 1.5-hour anoxic/anaerobic period, 5.5-hour aerobic period, 5 minutes of settling period, and 12 minutes of decanting period. Leachate was collected from Brady Road Resource Management Facility (landfill) in Winnipeg. Due to the high concentration of ammonia nitrogen and COD, leachate was gradually introduced to the reactors by mixing with primary effluent from SEWPCC at volumetric ratios varying from 10 to 100%. The characteristics of leachate and primary effluent are shown in Table 1. Table 1. The characteristics of the leachate and municipal wastewater Parameter NH4+-N (mg/L) NO2--N (mg/L) NO3--N (mg/L) PO43--P (mg/L) COD (mg/L) BOD/COD pH
Leachate 700-1200
SUMMARY: Landfill leachate treatment was investigated using two anaerobic/aerobic sequencing batch reactors (SBR) inoculated with suspended growth activated sludge (ASBR) and aerobic granular sludge (GSBR). The total ammonium nitrogen (TAN) concentration in the GSBR influent was as high as 1200 mgN/L with an average TAN removal efficiency of 99.7%. However, the ASBR treatment did not show a consistent performance in TAN removal. In GSBR, nitrification was partially inhibited at FA concentration from 48 to 57 mgN/L, which was two times more than the FA concentration that inhibited nitrification in ASBR. The low chemical oxygen demand (COD) removal efficiencies of GSBR and ASBR were associated with the refractory organic content of the leachate used in this study. The results prove that aerobic granular sludge is a robust method as compared to suspended activated sludge to treat leachate containing high levels of TAN and FA.
1. INTRODUCTION Leachate is a collection of wastewater generated in landfills due to the precipitation through municipal solid wastes, the liquid produced by biochemical processes in landfill cells, and the water constituent of the wastes (Renou et al. 2008). The composition of leachate is dependent on several factors, including temperature, precipitation, the composition of landfill waste, and the age of landfills. However, the main constituents of leachate include heavy metals, xenobiotic compounds, high concentrations of ammonium nitrogen, and biodegradable and refractory organic matter (Renou et al. 2008). Several alternative methods have been considered to treat leachate. Conventional activated sludge processes have been extensively applied to treat leachate or mixtures of leachate and domestic wastewater. Aerobic granular sludge (AGS) can be considered as a valuable alternative to biological treatment of leachate due to its peculiar characteristics. The AGS method presents unique characteristics, including high settling velocity, compact structure, simultaneous nutrient removal capability, and ability to sustain high biomass concentration (Adav et al., 2008). However, there has not been any major publications about leachate treatment by AGSR. An important contribution was provided by Wei et al. (2012), who used an SBR to develop AGS for leachate treatment. Their results indicated close to 83% of COD removal and nitrogen removal varied from 44% to 92% depending on the influent ammonia concentrations. Considering the advantages of AGS presented above and the lack of studies supporting AGS application in leachate treatment, this study aimed to compare the performance of AS and AGS in biological leachate treatment. Proceedings Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium/ 2 - 6 October 2017 S. Margherita di Pula, Cagliari, Italy / © 2017 by CISA Publisher, Italy
Sardinia 2017 / Sixteenth International Waste Management and Landfill Symposium / 2 - 6 October 2017
2. MATERIALS AND METHODS 2.1 Experimental setup Two lab-scale SBRs namely suspended activated sludge SBR (ASBR) and aerobic granular sludge SBR (GSBR) were inoculated with activated sludge collected from South End Water Pollution Control Centre (SEWPCC) in Winnipeg, Manitoba, Canada. The ASBR was operated at 3 cycles per day. Each cycle consisted of a 10-min feeding period, 1.5-hour anoxic/anaerobic period, 5.5 hours of aerobic (react), 40 minutes of settling, and 12 minutes of decanting. The solid retention time (SRT) in ASBR was set at 10 to 40 days. The GSBR was operated at 3 cycles per day. Each cycle consisted of 0.5-hour feeding period, 1.5-hour anoxic/anaerobic period, 5.5-hour aerobic period, 5 minutes of settling period, and 12 minutes of decanting period. Leachate was collected from Brady Road Resource Management Facility (landfill) in Winnipeg. Due to the high concentration of ammonia nitrogen and COD, leachate was gradually introduced to the reactors by mixing with primary effluent from SEWPCC at volumetric ratios varying from 10 to 100%. The characteristics of leachate and primary effluent are shown in Table 1. Table 1. The characteristics of the leachate and municipal wastewater Parameter NH4+-N (mg/L) NO2--N (mg/L) NO3--N (mg/L) PO43--P (mg/L) COD (mg/L) BOD/COD pH
Leachate 700-1200
