Michael Keleman - Academia.edu (original) (raw)

Papers by Michael Keleman

Research paper thumbnail of Characterization of typical household food wastes from disposers: Fractionation of constituents and implications for resource recovery at wastewater treatment

Bioresource Technology, May 1, 2015

h i g h l i g h t s Extensive detailed analysis of typical household FW with 33 different food ty... more h i g h l i g h t s Extensive detailed analysis of typical household FW with 33 different food types. COD and N were 3-5 folds higher in particulate form than in soluble form. COD/N ratios were higher in aqueous form (63:1) than particulates (42:1). FW can be an effective source of carbon for BNR and of N&P recovery from biosolids. The impact of FW on H 2 S generation in sewers is negligible.

Research paper thumbnail of Flocculent Settling of Food Wastes

Water Environment Research, Jul 1, 2016

This study evaluated the flocculent settling in water and municipal wastewater (MWW) in a 10.6 ft... more This study evaluated the flocculent settling in water and municipal wastewater (MWW) in a 10.6 ft deep column. A total of eight runs at three different testing conditions involving MWW alone, food waste (FW) alone, and FW in MWW (FWþMWW) were conducted. Total suspended solid (TSS), total BOD (TBOD), total COD (TCOD), total nitrogen (TN), and total phosphorous (TP) removal efficiencies after 3 hours of settling were 62%, 46%, 49%, 46% and 62% for FW, and 50%, 43%, 39%, 37% and 24% for MWW. Removal efficiencies of particulate COD (PCOD) and particulate BOD (PBOD) at the lowest surface overflow rate (SOR) of 1.1 m 3 /m 2 /hr corresponding to the longest settling time of 3 hours were 59% and 64% for FW, and 65% and 70% for FW with MWW samples. On the other hand, no significant variation between FW and FW with MWW was observed for PN removal after 3 hours of settling. Water Environ. Res., 88, 660 (2016).

Research paper thumbnail of Systematic Analysis of Factors That Affect Food-Waste Storage: Toward Maximizing Lactate Accumulation for Resource Recovery

ACS Sustainable Chemistry & Engineering, 2020

In the U.S., several states have attempted to mitigate greenhouse-gas emissions by banning food w... more In the U.S., several states have attempted to mitigate greenhouse-gas emissions by banning food wastes from landfills. As a result, U.S.-based companies are now providing decentralized foodwaste management systems for supermarkets and restaurants, which include storage as a slurry. It is unclear, however, which storage conditions (factors) would affect the spontaneous microbial activity, resulting in a different fermentation product spectra, and how this would further affect post-treatment. Here, we performed two experiments to mimic: 1) storage and 2) subsequent anaerobic digestion. For the food-waste storage system, we designed a mixed-level fractional factorial analysis with 12 experimental combinations, including separating food waste into: carbohydrate-rich, lipid-rich, and protein-rich food waste. We found that all factors that we tested affected the fermentation outcome. We observed that relatively low pH levels of 3-4, which were achieved due to rapid lactate accumulation by microbial activity during storage, coincided with greater lactate production and a maximum chemical oxygen demand (COD) selectivity of 90%. Food waste storage followed classical ensilage dynamics with homofermentation to lactate in combination with low pH preventing the subsequent breakdown of lacate into other carboxylic acids and hydrogen gas. The mechanistic understanding provides an opportunity to optimize lactate production, which is ideal for subsequent methane or chemical production.

Research paper thumbnail of Food waste as a resource: grinding, dilution, and storage as a pretreatment strategy to produce fermentation intermediates

In several states of the U.S., one measure to mitigate greenhouse-gas emissions has been to ban f... more In several states of the U.S., one measure to mitigate greenhouse-gas emissions has been to ban food wastes from landfills. As a result, U.S.-based companies are now providing decentralized food-waste management systems for supermarkets and restaurants, which include storage as a slurry. It is unclear, however, which storage conditions (factors) would affect the spontaneous microbial activity, resulting in a different fermentation product spectra, and how this would affect further post-treatment. Here, we performed two experiments to mimic: 1) storage and 2) subsequent anaerobic digestion. For the food-waste storage system, we designed a mixed-level fractional factorial analysis with 12 experimental combinations, including separating food waste into: carbohydrate-rich, lipid-rich, and protein-rich food waste. We found that all factors that we tested correlated with the fermentation product spectra, but that especially the factors: i) storage temperature; ii) food-waste composition; ...

Research paper thumbnail of Modeling the impact of food wastes on wastewater treatment plants

Journal of Environmental Management, 2019

Food waste (FW) enriched with readily biodegradable organics can enhance biological nutrient remo... more Food waste (FW) enriched with readily biodegradable organics can enhance biological nutrient removal (BNR), and biogas production. This study conducted extensive wastewater treatment simulations using BioWin software to predict the impact of food waste on nutrient removal, biogas generation, and energy balance. A total of 114 scenarios were tested to simulate different treatment technologies i.e. conventional activated sludge, Modified Ludzack-Ettinger (MLE), anaerobic-anoxic-aerobic (A2O), Bardenpho, and 2nd generation BNR technologies. The simulations also included sidestream treatment for nitrogen removal, as well as mainstream partial nitrification based on BNR. The results showed that FW addition enhanced nitrogen removal and decreased effluent nitrogen for BNR processes by 3.6-7.9 mg/L for MLE, 0.6-1.3 mg/L for A2O, and 1-2.3 mg/L for Bardenpho. In addition, FW addition decreased net operational cost by 26%-63% for BNR processes operating at mainstream conventional dissolved oxygen (DO) of 2 mg/L, 24%-78% for partial nitrification system, 29%-54% for sidestream, and 23%-76% for sidestream with mainstream partial nitrification process. The total net energy benefit considering both the net change in aeration energy and methane energy for a typical 37,854 m 3 /d or 10 MGD plant increased with FW addition by 3300-7900 kWh/d with a variation between BNR types, due to a substantial increase in methane production. Carbon diversion scenarios showed that the higher primary treatment efficiencies decreased the net operational cost and increased net energy gain.

Research paper thumbnail of Synergism of co-digestion of food wastes with municipal wastewater treatment biosolids

Waste management (New York, N.Y.), Jan 24, 2016

Five semi-continuous flow anaerobic digesters treating a mixture of food waste (FW) and municipal... more Five semi-continuous flow anaerobic digesters treating a mixture of food waste (FW) and municipal biosolids (primary sludge and thickened wasted activated sludge) at an solids retention time (SRT) of 20 days and different blend ratios i.e. 0, 10%, 20%, 40% by volume with the fifth digester treating only biosolids at the same COD/N ratio as the 40% FW digester were operated to investigate co-digestion performance. Sixty days of steady-state operation at organic loading rates (OLR) of 2.2-3.85kgCOD/m(3)/d showed that COD removals were higher for the three co-digesters than for the two municipal biosolids digesters i.e. 61-69% versus 47-52%. Specific methane production per influent CODs were 1.3-1.8 folds higher in co-digestion than mono-digestion. The first-order COD degradation kinetic constants for co-digestion were more than double the mono-digestion. Additional methane production through synergism accounted for a minimum of 18-20% of the overall methane production. The estimated n...

Research paper thumbnail of Flocculent Settling of Food Wastes

Water environment research : a research publication of the Water Environment Federation, 2016

This study evaluated the flocculent settling in water and municipal wastewater (MWW) in a 10.6 ft... more This study evaluated the flocculent settling in water and municipal wastewater (MWW) in a 10.6 ft deep column. A total of eight runs at three different testing conditions involving MWW alone, food waste (FW) alone, and FW in MWW (FW+MWW) were conducted. Total suspended solid (TSS), total BOD (TBOD), total COD (TCOD), total nitrogen (TN), and total phosphorous (TP) removal efficiencies after 3 hours of settling were 62%, 46%, 49%, 46% and 62% for FW, and 50%, 43%, 39%, 37% and 24% for MWW. Removal efficiencies of particulate COD (PCOD) and particulate BOD (PBOD) at the lowest surface overflow rate (SOR) of 1.1 m(3)/m(2)/hr corresponding to the longest settling time of 3 hours were 59% and 64% for FW, and 65% and 70% for FW with MWW samples. On the other hand, no significant variation between FW and FW with MWW was observed for PN removal after 3 hours of settling.

Research paper thumbnail of Overlooked & Misunderstood: The Essential Role of Food Waste Disposers in Diverting Food Scraps from Landfills to Beneficial Use

Proceedings of the Water Environment Federation, 2008

Research paper thumbnail of Characterization of typical household food wastes from disposers: Fractionation of constituents and implications for resource recovery at wastewater treatment

Bioresource technology, Jan 13, 2015

Food wastes with typical US food composition were analyzed to characterize different constituents... more Food wastes with typical US food composition were analyzed to characterize different constituents in both particulate and soluble phases i.e., solids, chemical oxygen demand (COD), 5-day biochemical oxygen demand (BOD), nitrogen (N), phosphorus (P). Relationships between various pollutants were also investigated using 50 samples. One gram of dry food waste generated 1.21g COD, 0.58g BOD5, 0.36g Total SS, 0.025g Total N, and 0.013g Total P. Distribution of constituents between particulate and aqueous phases indicated that 40% of COD and 30% of nitrogen were present in soluble form. Relative mass ratios of COD and nitrogen to solids were three to five times higher in particulates than in aqueous phase. However, COD/N ratios were higher in aqueous form than particulates at 63:1 versus 42:1. Detailed relationships between parameters showed that COD, nitrogen, and phosphorus in particulates are 200%, 3.6%, and 3.5% of the volatile suspended solids.

Research paper thumbnail of Food Waste to Renewable Energy

Proceedings of the Water Environment Federation, 2010

Research paper thumbnail of Microbial communities in co-digestion of food wastes and wastewater biosolids

Bioresource Technology, 2019

The effect of food waste (FW) co-digestion with wastewater biosolids (WWB) on microbial communiti... more The effect of food waste (FW) co-digestion with wastewater biosolids (WWB) on microbial communities was investigated through running thirteen lab-scale digesters for 100 days at different operational conditions i.e. organic loading rates (2 and 4 kgCOD/m 3 •day), feed types (WWB and FW), and FW content (10%, 90%, 100%). Compared with mono-digestion of WWB, FW co-digestion enhanced biogas production by 13% and COD degradation rates by up to 101%. Among fermentative bacteria/acetogens, Syntrophomonas was the dominant genus in FW digesters in contrast to the dominance of Clostridium in WWB digesters. The predominant methanogen was Methanosarcina in FW digesters in contrast to Methanosaeta in WWB digesters. COD degradation rates and methane yields were well correlated with Bacteroidetes population. Methane production rate was well correlated with Clostridium for FW digesters, with syntrophs for WWB digesters, and with aceticlastic methanogens for both digesters. Synergism was associated with hydrolytic bacteria, Clostridium, Syntrophomonas, syntrophs, Methanosarcina, and Methanobacterium.

Research paper thumbnail of Synergistic Effects of Codigesting Preprocessed Food Waste Slurry

Proceedings of the Water Environment Federation, 2017

Anaerobic digestion is the most widely used technology to produce biogas such as methane and hydr... more Anaerobic digestion is the most widely used technology to produce biogas such as methane and hydrogen from the decomposition of organic compounds. The effectiveness of the process depends on the stability of the consecutive reactions i.e. hydrolysis, acidification, acetogenesis, and methanogenesis. The process is widely used in sludge treatment for stabilization and production of methane gas. Due to the recent demand of renewable energy, anaerobic digestion has also been used for treating biodegradable wastes; for instance, the organic fraction of municipal solids wastes, wastewater treatment biosolids, and various food and beverage wastes (Arsova, 2010). Particularly, anaerobic digestion of food wastes (FW) is also considered as one of the effective methods of waste management. However, digestion stability can be hampered when FW is used as single substrate due to the high variability of its composition depending on its source (Lacovidou et al., 2012). Thus, the use of FW as co-substrate for municipal sludge digestion has emerged to enhance sludge digestibility, and increase energy generation to facilitate the achievability of energy-neutral wastewater treatment.

Research paper thumbnail of Characterization of typical household food wastes from disposers: Fractionation of constituents and implications for resource recovery at wastewater treatment

Bioresource Technology, May 1, 2015

h i g h l i g h t s Extensive detailed analysis of typical household FW with 33 different food ty... more h i g h l i g h t s Extensive detailed analysis of typical household FW with 33 different food types. COD and N were 3-5 folds higher in particulate form than in soluble form. COD/N ratios were higher in aqueous form (63:1) than particulates (42:1). FW can be an effective source of carbon for BNR and of N&P recovery from biosolids. The impact of FW on H 2 S generation in sewers is negligible.

Research paper thumbnail of Flocculent Settling of Food Wastes

Water Environment Research, Jul 1, 2016

This study evaluated the flocculent settling in water and municipal wastewater (MWW) in a 10.6 ft... more This study evaluated the flocculent settling in water and municipal wastewater (MWW) in a 10.6 ft deep column. A total of eight runs at three different testing conditions involving MWW alone, food waste (FW) alone, and FW in MWW (FWþMWW) were conducted. Total suspended solid (TSS), total BOD (TBOD), total COD (TCOD), total nitrogen (TN), and total phosphorous (TP) removal efficiencies after 3 hours of settling were 62%, 46%, 49%, 46% and 62% for FW, and 50%, 43%, 39%, 37% and 24% for MWW. Removal efficiencies of particulate COD (PCOD) and particulate BOD (PBOD) at the lowest surface overflow rate (SOR) of 1.1 m 3 /m 2 /hr corresponding to the longest settling time of 3 hours were 59% and 64% for FW, and 65% and 70% for FW with MWW samples. On the other hand, no significant variation between FW and FW with MWW was observed for PN removal after 3 hours of settling. Water Environ. Res., 88, 660 (2016).

Research paper thumbnail of Systematic Analysis of Factors That Affect Food-Waste Storage: Toward Maximizing Lactate Accumulation for Resource Recovery

ACS Sustainable Chemistry & Engineering, 2020

In the U.S., several states have attempted to mitigate greenhouse-gas emissions by banning food w... more In the U.S., several states have attempted to mitigate greenhouse-gas emissions by banning food wastes from landfills. As a result, U.S.-based companies are now providing decentralized foodwaste management systems for supermarkets and restaurants, which include storage as a slurry. It is unclear, however, which storage conditions (factors) would affect the spontaneous microbial activity, resulting in a different fermentation product spectra, and how this would further affect post-treatment. Here, we performed two experiments to mimic: 1) storage and 2) subsequent anaerobic digestion. For the food-waste storage system, we designed a mixed-level fractional factorial analysis with 12 experimental combinations, including separating food waste into: carbohydrate-rich, lipid-rich, and protein-rich food waste. We found that all factors that we tested affected the fermentation outcome. We observed that relatively low pH levels of 3-4, which were achieved due to rapid lactate accumulation by microbial activity during storage, coincided with greater lactate production and a maximum chemical oxygen demand (COD) selectivity of 90%. Food waste storage followed classical ensilage dynamics with homofermentation to lactate in combination with low pH preventing the subsequent breakdown of lacate into other carboxylic acids and hydrogen gas. The mechanistic understanding provides an opportunity to optimize lactate production, which is ideal for subsequent methane or chemical production.

Research paper thumbnail of Food waste as a resource: grinding, dilution, and storage as a pretreatment strategy to produce fermentation intermediates

In several states of the U.S., one measure to mitigate greenhouse-gas emissions has been to ban f... more In several states of the U.S., one measure to mitigate greenhouse-gas emissions has been to ban food wastes from landfills. As a result, U.S.-based companies are now providing decentralized food-waste management systems for supermarkets and restaurants, which include storage as a slurry. It is unclear, however, which storage conditions (factors) would affect the spontaneous microbial activity, resulting in a different fermentation product spectra, and how this would affect further post-treatment. Here, we performed two experiments to mimic: 1) storage and 2) subsequent anaerobic digestion. For the food-waste storage system, we designed a mixed-level fractional factorial analysis with 12 experimental combinations, including separating food waste into: carbohydrate-rich, lipid-rich, and protein-rich food waste. We found that all factors that we tested correlated with the fermentation product spectra, but that especially the factors: i) storage temperature; ii) food-waste composition; ...

Research paper thumbnail of Modeling the impact of food wastes on wastewater treatment plants

Journal of Environmental Management, 2019

Food waste (FW) enriched with readily biodegradable organics can enhance biological nutrient remo... more Food waste (FW) enriched with readily biodegradable organics can enhance biological nutrient removal (BNR), and biogas production. This study conducted extensive wastewater treatment simulations using BioWin software to predict the impact of food waste on nutrient removal, biogas generation, and energy balance. A total of 114 scenarios were tested to simulate different treatment technologies i.e. conventional activated sludge, Modified Ludzack-Ettinger (MLE), anaerobic-anoxic-aerobic (A2O), Bardenpho, and 2nd generation BNR technologies. The simulations also included sidestream treatment for nitrogen removal, as well as mainstream partial nitrification based on BNR. The results showed that FW addition enhanced nitrogen removal and decreased effluent nitrogen for BNR processes by 3.6-7.9 mg/L for MLE, 0.6-1.3 mg/L for A2O, and 1-2.3 mg/L for Bardenpho. In addition, FW addition decreased net operational cost by 26%-63% for BNR processes operating at mainstream conventional dissolved oxygen (DO) of 2 mg/L, 24%-78% for partial nitrification system, 29%-54% for sidestream, and 23%-76% for sidestream with mainstream partial nitrification process. The total net energy benefit considering both the net change in aeration energy and methane energy for a typical 37,854 m 3 /d or 10 MGD plant increased with FW addition by 3300-7900 kWh/d with a variation between BNR types, due to a substantial increase in methane production. Carbon diversion scenarios showed that the higher primary treatment efficiencies decreased the net operational cost and increased net energy gain.

Research paper thumbnail of Synergism of co-digestion of food wastes with municipal wastewater treatment biosolids

Waste management (New York, N.Y.), Jan 24, 2016

Five semi-continuous flow anaerobic digesters treating a mixture of food waste (FW) and municipal... more Five semi-continuous flow anaerobic digesters treating a mixture of food waste (FW) and municipal biosolids (primary sludge and thickened wasted activated sludge) at an solids retention time (SRT) of 20 days and different blend ratios i.e. 0, 10%, 20%, 40% by volume with the fifth digester treating only biosolids at the same COD/N ratio as the 40% FW digester were operated to investigate co-digestion performance. Sixty days of steady-state operation at organic loading rates (OLR) of 2.2-3.85kgCOD/m(3)/d showed that COD removals were higher for the three co-digesters than for the two municipal biosolids digesters i.e. 61-69% versus 47-52%. Specific methane production per influent CODs were 1.3-1.8 folds higher in co-digestion than mono-digestion. The first-order COD degradation kinetic constants for co-digestion were more than double the mono-digestion. Additional methane production through synergism accounted for a minimum of 18-20% of the overall methane production. The estimated n...

Research paper thumbnail of Flocculent Settling of Food Wastes

Water environment research : a research publication of the Water Environment Federation, 2016

This study evaluated the flocculent settling in water and municipal wastewater (MWW) in a 10.6 ft... more This study evaluated the flocculent settling in water and municipal wastewater (MWW) in a 10.6 ft deep column. A total of eight runs at three different testing conditions involving MWW alone, food waste (FW) alone, and FW in MWW (FW+MWW) were conducted. Total suspended solid (TSS), total BOD (TBOD), total COD (TCOD), total nitrogen (TN), and total phosphorous (TP) removal efficiencies after 3 hours of settling were 62%, 46%, 49%, 46% and 62% for FW, and 50%, 43%, 39%, 37% and 24% for MWW. Removal efficiencies of particulate COD (PCOD) and particulate BOD (PBOD) at the lowest surface overflow rate (SOR) of 1.1 m(3)/m(2)/hr corresponding to the longest settling time of 3 hours were 59% and 64% for FW, and 65% and 70% for FW with MWW samples. On the other hand, no significant variation between FW and FW with MWW was observed for PN removal after 3 hours of settling.

Research paper thumbnail of Overlooked & Misunderstood: The Essential Role of Food Waste Disposers in Diverting Food Scraps from Landfills to Beneficial Use

Proceedings of the Water Environment Federation, 2008

Research paper thumbnail of Characterization of typical household food wastes from disposers: Fractionation of constituents and implications for resource recovery at wastewater treatment

Bioresource technology, Jan 13, 2015

Food wastes with typical US food composition were analyzed to characterize different constituents... more Food wastes with typical US food composition were analyzed to characterize different constituents in both particulate and soluble phases i.e., solids, chemical oxygen demand (COD), 5-day biochemical oxygen demand (BOD), nitrogen (N), phosphorus (P). Relationships between various pollutants were also investigated using 50 samples. One gram of dry food waste generated 1.21g COD, 0.58g BOD5, 0.36g Total SS, 0.025g Total N, and 0.013g Total P. Distribution of constituents between particulate and aqueous phases indicated that 40% of COD and 30% of nitrogen were present in soluble form. Relative mass ratios of COD and nitrogen to solids were three to five times higher in particulates than in aqueous phase. However, COD/N ratios were higher in aqueous form than particulates at 63:1 versus 42:1. Detailed relationships between parameters showed that COD, nitrogen, and phosphorus in particulates are 200%, 3.6%, and 3.5% of the volatile suspended solids.

Research paper thumbnail of Food Waste to Renewable Energy

Proceedings of the Water Environment Federation, 2010

Research paper thumbnail of Microbial communities in co-digestion of food wastes and wastewater biosolids

Bioresource Technology, 2019

The effect of food waste (FW) co-digestion with wastewater biosolids (WWB) on microbial communiti... more The effect of food waste (FW) co-digestion with wastewater biosolids (WWB) on microbial communities was investigated through running thirteen lab-scale digesters for 100 days at different operational conditions i.e. organic loading rates (2 and 4 kgCOD/m 3 •day), feed types (WWB and FW), and FW content (10%, 90%, 100%). Compared with mono-digestion of WWB, FW co-digestion enhanced biogas production by 13% and COD degradation rates by up to 101%. Among fermentative bacteria/acetogens, Syntrophomonas was the dominant genus in FW digesters in contrast to the dominance of Clostridium in WWB digesters. The predominant methanogen was Methanosarcina in FW digesters in contrast to Methanosaeta in WWB digesters. COD degradation rates and methane yields were well correlated with Bacteroidetes population. Methane production rate was well correlated with Clostridium for FW digesters, with syntrophs for WWB digesters, and with aceticlastic methanogens for both digesters. Synergism was associated with hydrolytic bacteria, Clostridium, Syntrophomonas, syntrophs, Methanosarcina, and Methanobacterium.

Research paper thumbnail of Synergistic Effects of Codigesting Preprocessed Food Waste Slurry

Proceedings of the Water Environment Federation, 2017

Anaerobic digestion is the most widely used technology to produce biogas such as methane and hydr... more Anaerobic digestion is the most widely used technology to produce biogas such as methane and hydrogen from the decomposition of organic compounds. The effectiveness of the process depends on the stability of the consecutive reactions i.e. hydrolysis, acidification, acetogenesis, and methanogenesis. The process is widely used in sludge treatment for stabilization and production of methane gas. Due to the recent demand of renewable energy, anaerobic digestion has also been used for treating biodegradable wastes; for instance, the organic fraction of municipal solids wastes, wastewater treatment biosolids, and various food and beverage wastes (Arsova, 2010). Particularly, anaerobic digestion of food wastes (FW) is also considered as one of the effective methods of waste management. However, digestion stability can be hampered when FW is used as single substrate due to the high variability of its composition depending on its source (Lacovidou et al., 2012). Thus, the use of FW as co-substrate for municipal sludge digestion has emerged to enhance sludge digestibility, and increase energy generation to facilitate the achievability of energy-neutral wastewater treatment.