Algal–bacterial symbiosis, implemented in an innovative anoxic–aerobic photobioreactor configurat... more Algal–bacterial symbiosis, implemented in an innovative anoxic–aerobic photobioreactor configuration with biomass recycling, supported an efficient removal of total organic carbon (86–90%), inorganic carbon (57–98%) and total nitrogen (68–79%) during synthetic wastewater treatment at a hydraulic and sludge retention times of 2 days and 20 days, respectively. The availability of inorganic carbon in the photobioreactor, determined by its supply in the wastewater and microalgae activity, governed the extent of nitrogen removal by assimilation or nitrification–denitrification. Unexpectedly, nitrate production was negligible despite the high dissolved oxygen concentrations, denitrification being only based on nitrite reduction. Biomass recycling resulted in the enrichment of rapidly settling algal flocs, which supported effluent total suspended solid concentrations below the European Union maximum discharge limits. Finally, the maximum nitrous oxide emissions recorded were far below the emission factors reported for wastewater treatment plants, confirming the environmental sustainability of this innovative photobioreactor in terms of global warming impact.
The present research was conducted to simultaneously optimize biogas upgrading and carbon and nut... more The present research was conducted to simultaneously optimize biogas upgrading and carbon and nutrient removal from centrates in a 180-L high-rate algal pond interconnected to an external CO 2 absorption unit. Different biogas and centrate supply strategies were assessed to increase bio-mass lipid content. Results showed 99 % CO 2 removal effi-ciencies from simulated biogas at liquid recirculation rates in the absorption column of 9.9 m 3 m −2 h −1 , concomitant with nitrogen and phosphorus removal efficiencies of 100 and 82 %, respectively, using a 1:70 diluted centrate at a hydraulic retention time of 7 days. The lipid content of the harvested algal–bacterial biomass remained low (2.9–11.2 %) regardless of the operational conditions, with no particular trend over time. The good settling characteristics of the algal–bacterial flocs resulted in harvesting efficiencies over 95 %, which represents a cost-effective alternative for algal biomass reutiliza-tion compared to conventional physical–chemical techniques. Finally, high microalgae biodiversity was found regardless of the operational conditions.
A pilot high rate algal pond (HRAP) interconnected to an external CO 2 –H 2 S absorption column v... more A pilot high rate algal pond (HRAP) interconnected to an external CO 2 –H 2 S absorption column via settled broth recirculation was used to simultaneously treat a synthetic digestate and to upgrade biogas to a bio-methane with sufficient quality to be injected into natural gas grids. An innovative HRAP operational strategy with biomass recirculation based on the control of algal-bacterial biomass productivity (2.2, 4.4 and 7.5 g m −2 d −1) via settled biomass wastage was evaluated in order to enhance nutrient recovery from digestate at a constant hydraulic retention time. The influence of the recycling liquid to biogas (L/G) ratio on the quality of the upgraded biogas was assessed. The bio-methane composition under a L/G ratio of 1 (0.4 ± 0.1% CO 2 , 0.03 ± 0.04% O 2 , 2.4 ± 0.2% N 2 and 97.2 ± 0.2% CH 4) complied with the technical specifications of most European bio-methane legislations regardless of the biomass productivity established. The HRAP operational strategy applied allowed increasing the N and P recovery from 19 and 22% to 83 and 100%, respectively, when the biomass productivity was increased from 2.2 to 7.5 g m −2 d −1. Finally, the dynamics of microalgae and bacteria population structure were characterized by morphological identification and Denaturing Gradient Gel Electrophoresis analysis.
Novel operational strategies to reduce the O 2 concentration in the upgraded biogas were evaluate... more Novel operational strategies to reduce the O 2 concentration in the upgraded biogas were evaluated in a 180 L algal–bacterial photobioreactor interconnected to a 2.5 L external absorption column during the simultaneous treatment of diluted anaerobically digested or raw vinasse and biogas upgrading. The lowest biomethane O 2 levels (0.7 ± 0.2%) were recorded when raw vinasse was fed directly into the absorption column, which resulted in CO 2 and H 2 S removals from biogas of 72 ± 1% and 100 ± 0%, respectively. Process operation at a Hydraulic Retention Time (HRT) of 7 d under the above configuration also supported the maximum total carbon, nitrogen and phosphorus removals of 72 ± 4%, 74 ± 3% and 78 ± 5%, respectively. Biomass productivity ranged from 11.4 ± 1.8 to 13.5 ± 2.2 g m −2 d −1 during microalgae cultivation in diluted anaerobically digested vinasse, while this productivity increased to 16.9 ± 0.7 g m −2 d −1 when feeding diluted raw vinasse. The good settling characteristics of the algal–bacterial flocs resulted in an average harvesting efficiency of 98.6 ± 0.5% at a HRT in the settler of 23 min, regardless of the treated vinasse. The morphological and molecular characterization of the microbial communities showed a high microalgae diversity and bacterial species richness, regardless of the operational conditions (Shannon–Wiener indices ranging from 2.8 to 3.3).
Three sludge pre-treatments, thermal hydrolysis, advanced thermal hydrolysis and enzymatic auto-h... more Three sludge pre-treatments, thermal hydrolysis, advanced thermal hydrolysis and enzymatic auto-hydrolysis, were evaluated in order to compare their effect on the potential odour footprint of secondary sludge. The odorous emission was characterized by SPME-GC-MS. The results demonstrated that thermal hydrolysis removed most of the odorous compounds from the initial sludge, and the experiments without H 2 O 2 showed better results than those with oxidant addition. The auto-hydrolysis process did not reduce the odour emission potential from the initial sludge and produced additional odorous substances regardless of the conditions and process duration.
Despite several fungal strains have been retrieved from methane-containing environments, the actu... more Despite several fungal strains have been retrieved from methane-containing environments, the actual capacity and role of fungi on methane abatement is still unclear. The batch biodegradation tests here performed demonstrated the capacity of Graphium sp. to co-metabolically biodegrade methane and methanol. Moreover, the performance and microbiology of a fungal-bacterial compost biofilter treating methane at concentrations of ∼2% was evaluated at empty bed residence times of 40 and 20 min under different irrigation rates. The daily addition of 200 mL of mineral medium resulted in elimination capacities of 36.6 ± 0.7 g m(-3) h(-1) and removal efficiencies of ≈90% at the lowest residence time. The indigenous fungal community of the compost was predominant in the final microbial population and outcompeted the inoculated Graphium sp. during biofilter operation.
Piggery wastewater is characterized by its high content in nitrogen and phosphorus, as well as by... more Piggery wastewater is characterized by its high content in nitrogen and phosphorus, as well as by a low C/N ratio. This type of wastewater is traditionally spread to croplands (with its subsequent leaching to groundwater) or rarely discharged into natural water bodies, which ultimately cause severe episodes of eutrophication in aquatic ecosystems. In this context, activated sludge systems constitute a robust and efficient treatment option. The performance of an activated sludge process using a pre-denitrification configuration treating both sieved and flocculated swine slurry at a hydraulic retention time (HRT) of 7.7 days was evaluated. In order to avoid bacterial wash-out, sludge from the settler was recirculated to the anoxic tank to accomplish denitrification. Once the biomass was acclimatized, the reactor was fed with swine slurry containing 19, 2.6, and 0.27 g/L of total chemical oxygen demand (COD), total Kjeldhal nitrogen (TKN), and soluble P, respectively. Nitrogen removal ...
Proceedings of the Water Environment Federation, 2012
ABSTRACT Technologies for odor control have been widely reviewed and their optimal range of appli... more ABSTRACT Technologies for odor control have been widely reviewed and their optimal range of application and performance has been clearly established. Selection criteria, mainly driven by process economics, are usually based on the air flow volume, the inlet concentrations and the required removal efficiency. However, these criteria are shifting with social and environmental issues becoming as important as process economics.Odor abatement systems are designed for long term operation, preferably with minimum operator involvement and without any failures. This means that the operational risk is critical, because operational experience shows that when a technology is not critical for the main objectives of a facility (e.g. purify wastewater, production of a product, etc.) a lower priority is often given in terms of operator and maintenance attention.This paper presents results from several studies to quantify Sustainability and Robustness of odor control technology in the context of odor control at wastewater treatment or water recycling plants. The most commonly used odor abatement techniques (biofiltration, biotrickling filtration, activated carbon adsorption, chemical scrubbing, activated sludge diffusion and biotrickling filtration coupled with activated carbon adsorption) are evaluated in terms of: 1. Sustainability, with quantification of process economics, environmental performance and social impact using the IChemE Sustainability Metrics. 2. Sensitivity towards design and operating parameters like utility prices (energy and labor), inlet odor concentration (H2S) and design safety (EBRT). 3. Robustness, quantifications of operating reliability, with recommendations to improve reliability during its lifespan of operations.
Algal–bacterial symbiosis, implemented in an innovative anoxic–aerobic photobioreactor configurat... more Algal–bacterial symbiosis, implemented in an innovative anoxic–aerobic photobioreactor configuration with biomass recycling, supported an efficient removal of total organic carbon (86–90%), inorganic carbon (57–98%) and total nitrogen (68–79%) during synthetic wastewater treatment at a hydraulic and sludge retention times of 2 days and 20 days, respectively. The availability of inorganic carbon in the photobioreactor, determined by its supply in the wastewater and microalgae activity, governed the extent of nitrogen removal by assimilation or nitrification–denitrification. Unexpectedly, nitrate production was negligible despite the high dissolved oxygen concentrations, denitrification being only based on nitrite reduction. Biomass recycling resulted in the enrichment of rapidly settling algal flocs, which supported effluent total suspended solid concentrations below the European Union maximum discharge limits. Finally, the maximum nitrous oxide emissions recorded were far below the emission factors reported for wastewater treatment plants, confirming the environmental sustainability of this innovative photobioreactor in terms of global warming impact.
The present research was conducted to simultaneously optimize biogas upgrading and carbon and nut... more The present research was conducted to simultaneously optimize biogas upgrading and carbon and nutrient removal from centrates in a 180-L high-rate algal pond interconnected to an external CO 2 absorption unit. Different biogas and centrate supply strategies were assessed to increase bio-mass lipid content. Results showed 99 % CO 2 removal effi-ciencies from simulated biogas at liquid recirculation rates in the absorption column of 9.9 m 3 m −2 h −1 , concomitant with nitrogen and phosphorus removal efficiencies of 100 and 82 %, respectively, using a 1:70 diluted centrate at a hydraulic retention time of 7 days. The lipid content of the harvested algal–bacterial biomass remained low (2.9–11.2 %) regardless of the operational conditions, with no particular trend over time. The good settling characteristics of the algal–bacterial flocs resulted in harvesting efficiencies over 95 %, which represents a cost-effective alternative for algal biomass reutiliza-tion compared to conventional physical–chemical techniques. Finally, high microalgae biodiversity was found regardless of the operational conditions.
A pilot high rate algal pond (HRAP) interconnected to an external CO 2 –H 2 S absorption column v... more A pilot high rate algal pond (HRAP) interconnected to an external CO 2 –H 2 S absorption column via settled broth recirculation was used to simultaneously treat a synthetic digestate and to upgrade biogas to a bio-methane with sufficient quality to be injected into natural gas grids. An innovative HRAP operational strategy with biomass recirculation based on the control of algal-bacterial biomass productivity (2.2, 4.4 and 7.5 g m −2 d −1) via settled biomass wastage was evaluated in order to enhance nutrient recovery from digestate at a constant hydraulic retention time. The influence of the recycling liquid to biogas (L/G) ratio on the quality of the upgraded biogas was assessed. The bio-methane composition under a L/G ratio of 1 (0.4 ± 0.1% CO 2 , 0.03 ± 0.04% O 2 , 2.4 ± 0.2% N 2 and 97.2 ± 0.2% CH 4) complied with the technical specifications of most European bio-methane legislations regardless of the biomass productivity established. The HRAP operational strategy applied allowed increasing the N and P recovery from 19 and 22% to 83 and 100%, respectively, when the biomass productivity was increased from 2.2 to 7.5 g m −2 d −1. Finally, the dynamics of microalgae and bacteria population structure were characterized by morphological identification and Denaturing Gradient Gel Electrophoresis analysis.
Novel operational strategies to reduce the O 2 concentration in the upgraded biogas were evaluate... more Novel operational strategies to reduce the O 2 concentration in the upgraded biogas were evaluated in a 180 L algal–bacterial photobioreactor interconnected to a 2.5 L external absorption column during the simultaneous treatment of diluted anaerobically digested or raw vinasse and biogas upgrading. The lowest biomethane O 2 levels (0.7 ± 0.2%) were recorded when raw vinasse was fed directly into the absorption column, which resulted in CO 2 and H 2 S removals from biogas of 72 ± 1% and 100 ± 0%, respectively. Process operation at a Hydraulic Retention Time (HRT) of 7 d under the above configuration also supported the maximum total carbon, nitrogen and phosphorus removals of 72 ± 4%, 74 ± 3% and 78 ± 5%, respectively. Biomass productivity ranged from 11.4 ± 1.8 to 13.5 ± 2.2 g m −2 d −1 during microalgae cultivation in diluted anaerobically digested vinasse, while this productivity increased to 16.9 ± 0.7 g m −2 d −1 when feeding diluted raw vinasse. The good settling characteristics of the algal–bacterial flocs resulted in an average harvesting efficiency of 98.6 ± 0.5% at a HRT in the settler of 23 min, regardless of the treated vinasse. The morphological and molecular characterization of the microbial communities showed a high microalgae diversity and bacterial species richness, regardless of the operational conditions (Shannon–Wiener indices ranging from 2.8 to 3.3).
Three sludge pre-treatments, thermal hydrolysis, advanced thermal hydrolysis and enzymatic auto-h... more Three sludge pre-treatments, thermal hydrolysis, advanced thermal hydrolysis and enzymatic auto-hydrolysis, were evaluated in order to compare their effect on the potential odour footprint of secondary sludge. The odorous emission was characterized by SPME-GC-MS. The results demonstrated that thermal hydrolysis removed most of the odorous compounds from the initial sludge, and the experiments without H 2 O 2 showed better results than those with oxidant addition. The auto-hydrolysis process did not reduce the odour emission potential from the initial sludge and produced additional odorous substances regardless of the conditions and process duration.
Despite several fungal strains have been retrieved from methane-containing environments, the actu... more Despite several fungal strains have been retrieved from methane-containing environments, the actual capacity and role of fungi on methane abatement is still unclear. The batch biodegradation tests here performed demonstrated the capacity of Graphium sp. to co-metabolically biodegrade methane and methanol. Moreover, the performance and microbiology of a fungal-bacterial compost biofilter treating methane at concentrations of ∼2% was evaluated at empty bed residence times of 40 and 20 min under different irrigation rates. The daily addition of 200 mL of mineral medium resulted in elimination capacities of 36.6 ± 0.7 g m(-3) h(-1) and removal efficiencies of ≈90% at the lowest residence time. The indigenous fungal community of the compost was predominant in the final microbial population and outcompeted the inoculated Graphium sp. during biofilter operation.
Piggery wastewater is characterized by its high content in nitrogen and phosphorus, as well as by... more Piggery wastewater is characterized by its high content in nitrogen and phosphorus, as well as by a low C/N ratio. This type of wastewater is traditionally spread to croplands (with its subsequent leaching to groundwater) or rarely discharged into natural water bodies, which ultimately cause severe episodes of eutrophication in aquatic ecosystems. In this context, activated sludge systems constitute a robust and efficient treatment option. The performance of an activated sludge process using a pre-denitrification configuration treating both sieved and flocculated swine slurry at a hydraulic retention time (HRT) of 7.7 days was evaluated. In order to avoid bacterial wash-out, sludge from the settler was recirculated to the anoxic tank to accomplish denitrification. Once the biomass was acclimatized, the reactor was fed with swine slurry containing 19, 2.6, and 0.27 g/L of total chemical oxygen demand (COD), total Kjeldhal nitrogen (TKN), and soluble P, respectively. Nitrogen removal ...
Proceedings of the Water Environment Federation, 2012
ABSTRACT Technologies for odor control have been widely reviewed and their optimal range of appli... more ABSTRACT Technologies for odor control have been widely reviewed and their optimal range of application and performance has been clearly established. Selection criteria, mainly driven by process economics, are usually based on the air flow volume, the inlet concentrations and the required removal efficiency. However, these criteria are shifting with social and environmental issues becoming as important as process economics.Odor abatement systems are designed for long term operation, preferably with minimum operator involvement and without any failures. This means that the operational risk is critical, because operational experience shows that when a technology is not critical for the main objectives of a facility (e.g. purify wastewater, production of a product, etc.) a lower priority is often given in terms of operator and maintenance attention.This paper presents results from several studies to quantify Sustainability and Robustness of odor control technology in the context of odor control at wastewater treatment or water recycling plants. The most commonly used odor abatement techniques (biofiltration, biotrickling filtration, activated carbon adsorption, chemical scrubbing, activated sludge diffusion and biotrickling filtration coupled with activated carbon adsorption) are evaluated in terms of: 1. Sustainability, with quantification of process economics, environmental performance and social impact using the IChemE Sustainability Metrics. 2. Sensitivity towards design and operating parameters like utility prices (energy and labor), inlet odor concentration (H2S) and design safety (EBRT). 3. Robustness, quantifications of operating reliability, with recommendations to improve reliability during its lifespan of operations.
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Papers by Raul Muñoz
with biomass recycling, supported an efficient removal of total organic carbon (86–90%), inorganic carbon (57–98%) and total nitrogen (68–79%) during synthetic wastewater treatment at a hydraulic and
sludge retention times of 2 days and 20 days, respectively. The availability of inorganic carbon in the photobioreactor, determined by its supply in the wastewater and microalgae activity, governed the extent of
nitrogen removal by assimilation or nitrification–denitrification. Unexpectedly, nitrate production was
negligible despite the high dissolved oxygen concentrations, denitrification being only based on nitrite
reduction. Biomass recycling resulted in the enrichment of rapidly settling algal flocs, which supported
effluent total suspended solid concentrations below the European Union maximum discharge limits.
Finally, the maximum nitrous oxide emissions recorded were far below the emission factors reported
for wastewater treatment plants, confirming the environmental sustainability of this innovative photobioreactor in terms of global warming impact.
with biomass recycling, supported an efficient removal of total organic carbon (86–90%), inorganic carbon (57–98%) and total nitrogen (68–79%) during synthetic wastewater treatment at a hydraulic and
sludge retention times of 2 days and 20 days, respectively. The availability of inorganic carbon in the photobioreactor, determined by its supply in the wastewater and microalgae activity, governed the extent of
nitrogen removal by assimilation or nitrification–denitrification. Unexpectedly, nitrate production was
negligible despite the high dissolved oxygen concentrations, denitrification being only based on nitrite
reduction. Biomass recycling resulted in the enrichment of rapidly settling algal flocs, which supported
effluent total suspended solid concentrations below the European Union maximum discharge limits.
Finally, the maximum nitrous oxide emissions recorded were far below the emission factors reported
for wastewater treatment plants, confirming the environmental sustainability of this innovative photobioreactor in terms of global warming impact.