Separation of domestic effluents at the source and the utilization of low-flush toilets offer alt... more Separation of domestic effluents at the source and the utilization of low-flush toilets offer alternative approaches for developing efficient wastewater treatment systems while promoting energy generation through anaerobic digestion. This study focused on assessing toilet usage in Mexico and exploring the potential of anaerobic codigestion of brown water (feces) and toilet paper as influential factors in wastewater treatment systems. A survey was conducted on a representative sample of Mexicans to gather information on toilet usage frequency, toilet paper use and disposal practices, as well as the type and quantity of commercial disinfectants and pharmaceutical compounds they use or consume. The survey revealed that per capita toilet paper consumption is 2.9 kg annually, that 58 % of respondents do not dispose used paper in the toilet, and that about 47 % use two to three cleaning and disinfection products. Notably, 97 % of the sampled Mexican population expressed a willingness to transition to more eco-friendly toilet options. Subsequently, in a second step, the anaerobic codigestion of brown water with toilet paper was evaluated, demonstrating a relatively high production of volatile
fatty acids but low methane production. This suggests an efficient hydrolysis/acidogenesis process coupled with restrained methanogenesis, probably due to pH decrease caused by acidogenesis. This study underscores that toilet paper and brown water are potential suitable substrates for anaerobic co-digestion. Furthermore, it
sheds light on the behaviors of Mexican society regarding bathroom use and cleaning, contributing to the establishment of foundations for wastewater treatment systems with effluent separation at the source.
Las emulsiones multiples agua-en aceite-en agua (W1/O/W2) en el area ambiental se han propuesto p... more Las emulsiones multiples agua-en aceite-en agua (W1/O/W2) en el area ambiental se han propuesto para tratar aguas. Actualmente se ha sugerido entrampar un consorcio microbiano degradador de MTBE en el sistema de emulsiones multiples, para tratar agua contaminada con metil ter butil eter (MTBE), no obstante, es importante el uso de los materiales adecuados en la formulacion de la emulsion debido a que pueden interferir en la degradacion de MTBE. El objetivo de este estudio fue observar el consumo de los materiales que componen la emulsion multiple W1/O/W2 en presencia y ausencia de MTBE por el consorcio microbiano. Los materiales que se han propuesto para estabilizar la emulsion multiple W1/O/W2 son goma de mezquite (Prosopis laevigata), acido poliacrilico, aceite mineral ligero y Span 80. Se utilizaron cada uno de los anteriores compuestos por separado en una concentracion de 0.2% en microcosmos en ausencia y en presencia de MTBE, se cuantifico CO2 para advertir el consumo de los co...
This study is focused on the effect of thermo alkaline pretreatment on velocity of anaerobic hydr... more This study is focused on the effect of thermo alkaline pretreatment on velocity of anaerobic hydrolysis mesophilic and thermophilic of waste activated sludge (WAS), separating the hydrolysis of suspended solids (SS) and dissolved solids (SD). In order to research the hydrolysis of SS, the Sander’s surface model was used, and for the hydrolysis of SD, the Goel’s model of saturation was employed. The pretre tment increased the uperficial rea available for the enzymatic action, due to the reduction of the solids size. The effect of the pretreatment in the anaerobic digestion of the SD in thermophilic conditions, resulted in competitive inhibition over the anaerobic hydrolysis rate, whereas that in mesophilic conditions, resulted in non competitive inhibition. Mathematical simulation of SS to SD and methane consecutive reactions, showed that a 4 % increase in initial thermal-alkaline tr ated sludge di inished the inhibition of SD hydrolysis in the thermophilic anaerobic digestion.
The present research studies of mesophilic hydrolysis (AM) and stabilization under thermophilic m... more The present research studies of mesophilic hydrolysis (AM) and stabilization under thermophilic methanogenic conditions (MT) for a mixture of primary sludge (PS) and secondary sludge (SS) using two serial Upflow Anaerobic Sludge Blanket reactors (UASB). The AM and MT reactors were operated at 32 ± 2 °C and 56 ± 1 °C, respectively with different rates of PS:SS in the supply, without stir or recirculation at different hydraulic retention times (HRT). The AM reactor showed the optimal results in the stage V, HRT of 2 days, solid retention times (SRT) of 18.1 for a PS:SS rate of 50:50, and volumetric loading (Bv) of 3.6 kg DQO/m3.d., and it was observed a COD removal efficiency of 56.8%, soluble COD production of 48.3%, volatile suspended solids (VSS) removal of 68.6% using a hydrolysis rate of 0.16 kg/m3.d. The MT reactor showed the optimal stabilization for HRT on the 6th day of operation, methane (CH4) production of 107.7 mL CH4/ Kg VSSremoved, VSS removal of 66%, faecal coliform eli...
Aquatic plant biomass has been shown to have a great potential for biogas production. The use of ... more Aquatic plant biomass has been shown to have a great potential for biogas production. The use of ruminal fluid has been shown to improve the degradation of the lignocellulosic material with its conversion into volatile fatty acids (VFA) during a first phase of hydrolysis–acidogenesis. VFAs are important as the feedstock for methane and hydrogen production in a second phase process within a biorefinery. The objective of this work was to produce a high yield of VFA during a first phase of anaerobic hydrolysis–acidogenesis of Pistia stratiotes biomass assessing the effect of the use of rumen fluid as inoculum and of daily adjustment of pH in batch-operated reactors. One liter anaerobic reactors containing 15 gSV L−1 of P. stratiotes biomass were incubated at 30 ± 2 °C and agitated once a day. The inoculum concentration had no significant effect on the increase in VFA concentration and 20 % (V/V) was used in all treatments. The final average VFA concentration and conversion coefficients from VS to VFA in the inoculated treatment with no pH adjustment (T1) and with pH adjustment (T2) (1817 mgCOD L−1 and 0.1319 mgVFA mgVS−1, respectively) were significantly higher than those found in the treatment with no inoculum (T0). There were no significant differences between T0 and T1 in the VS degradation rate. In contrast, the degradation rate in T2 was significantly higher. Thus, the addition of ruminal fluid promoted the production of VFA, and the pH adjustment had no significant effect on this parameter but did influence the biomass degradation.
This study is focused on the e�ect of thermo alkaline pretreatment on velocity of anaerobic hydro... more This study is focused on the e�ect of thermo alkaline pretreatment on velocity of anaerobic hydrolysis mesophilic and thermophilic of waste activated sludge (WAS), separating the hydrolysis of suspended solids (SS) and dissolved solids (SD). In order to research the hydrolysis of SS, the Sander¿s surface model was used, and for the hydrolysis of SD, the Goel¿s model of saturation was employed. The pretreatment increased the superficial area available for the enzymatic action, due to the reduction of the solids size. The e�ect of the pretreatment in the anaerobic digestion of the SD in thermophilic conditions, resulted in competitive inhibition over the anaerobic hydrolysis rate, whereas that in mesophilic conditions, resulted in non competitive inhibition. Mathematical simulation of SS to SD and methane consecutive reactions, showed that a 4 % increase in initial thermal-alkaline treated sludge diminished the inhibition of SD hydrolysis in the thermophilic anaerobic digestion.
The kinetics of the acidogenic and methanogenic stages of lactose digestion were studied in two i... more The kinetics of the acidogenic and methanogenic stages of lactose digestion were studied in two independent upflow anaerobic sludge bed (UASB) reactors. The acidogenic reactor stage was fed on lactose (1 g/L) at several specific organic loading rates (SOLR) (0.2, 0.4, 0,8, 1 and 1.6 g COD/g VSS.d). At 1.0 g COD/VSS.d the acidogenic and methanogenic conversions were highest with acetate being 67% of total VFA (50% on a COD basis) while the COD degradation rate was minimal 0.2 g CODdeg/g VSS.d. The methanogenic reactor was fed on acetate-lactose mixtures (100,75, 50, 25, 0% acetate) at an OLR of 0.41 g COD/g VSS.d with the best performance at 50%. The results show that in order to control a two stage anaerobic process, the control strategies should be put on the acidogenic reactor in order to produce a fixed acetate percentage in the feed to the methanogenic reactor.
Bulletin of Environmental Contamination and Toxicology, 1999
) is a pesticide that belongs to the group of organochlorines. It has beenextensively used since ... more ) is a pesticide that belongs to the group of organochlorines. It has beenextensively used since the Second World War all over the world and, even though its useis banned or restricted in many countries because of its deleterious effects, it is stillcommonly found in the environment, especially in the soil, due to its strong adsorption tosolid particles, which results in a great persistency (EPA, 1986). Some investigationshave reported that the DDT present in the soil can be degraded in two years, while othershave found that the process can take from fifteen to twenty years or more (Alexander,1994).The degradation products of DDT are mainly the dechlorination products DDE and DDD.The pathway can be DDT → DDE → DDD, or from DDT to DDD directly. These routeshave not been completely established, even after 40 years of studies (Wayland et al.,1991). In anaerobic marine sediments DDE is readily dechlorinated to DDMU (Quensenet al., 1998).In less developed countries, the use of DDT still continues in order to control diseasessuch as malaria and dengue (Wayland et al., 1991; Cebrian, 1998). So far, no chemicalcompound has been found that brings together DDT’s properties and effectiveness. InMexico, the use of DDT is higher than in any other Latin American country (PAHO,1994). Mexico used about 1000 tons of DDT in 1992 (Sharpe, 1995). The production ofDDT in Mexico is mostly for its own use. Though production has diminished since 1970,it has remained stable since 1985 (Lopez-Carrillo et al., 1996). In a study carried out inthe state of Veracruz in Mexico, DDT and DDE were determined in the adipose tissue ofpeople. These compounds were present in all the cases analyzed and the highest levelswere found in a suburban zone. Average DDT concentration was 24.82 mg/kg, veryhigh compared to the results in other countries (Waliszewski et al., 1995).In recent years, there has been renewed research interest in DDT, since it has beenassociated with several health problems, including the increased risk of breast cancer inwomen and alterations in reproductive functions in men (Cebrian, 1998).DDT is a chlorinated organic compound that is highly resistant to degradation bybiological, photolithical and chemical means, given that its molecular structure containschlorinated aliphatic and aromatic structures that impart great chemical stability.Because of this, DDT is a recalcitrant, toxic, persistent pollutant (Kannan et al., 1992).This explains the current interest in developing bioremediation processes for thiscompound.Current bioremediation processes typically use aerobic bacteria to degrade petroleum andother chemical wastes by oxidation of the compounds. However, it has been observedthat anaerobic systems are often more capable of degrading chlorinated pollutants byreductive dechlorination (Leahy and Brown, 1994). Some compounds, such aspolychlorinated biphenyls (PCBs) can be initially dechlorinated and partially degraded by
Two stages anaerobic digestion of the organic fraction of municipal solid wastes (OFMSW) is propo... more Two stages anaerobic digestion of the organic fraction of municipal solid wastes (OFMSW) is proposed using a batch anaerobic trickling bed (BATB) reactor in the first hydrolysis and acidogenesis stage. At total solids loading of 135 g/L and reaction times around 30 days, total solids (ηTS) and chemical oxygen demand (ηCOD) removal efficiencies above 46% were obtained independently of pH (between 4.1 and 6.4). Dependent on pH were methane production, four times more at pH 6.4 than at 4.8 and four times more volatile fatty acids (VFA) production at 6.4 than at 4.1 and twice than at 4.8. Leachates generated in the BATB reactor were diluted with municipal wastewater and fed to an upflow anaerobic sludge blanket (UASB) reactor at volumetric organic loading rates from 11 to 28 g/L.d where 90% COD removal efficiencies (ηCOD) and 11.4 g CODCH4./L.d were obtained. Two stages anaerobic digestion results in high rates of solids removal and methane production (0.63 kWhr/kg TS fed).
Presencia UniversitariaLa planeación por cuencas es sustancial para el manejo sustentable del agu... more Presencia UniversitariaLa planeación por cuencas es sustancial para el manejo sustentable del agua. En donde se genera se debe preservar y usar. A partir de este paradigma se plantean dos estrategias para la conservación del recurso: una es aumentar la captación y otra es reducir la extracción. A partir de ellas se plantean acciones y se resaltan las tecnologías que hace falta desarrollar en México para alcanzar la sustentabilidad. Es necesaria una política pública para pasar del bombeo, que es la única tecnología actual para manejar el agua, a una variedad de tecnologías para incrementar su captación, uso eficiente, tratamiento y reuso. Hay que conjuntar las políticas de manejo de agua, producción de alimentos, de vivienda y empleo para que con la participación pública se alcance para todos un digno nivel de vida. Se ejemplifica esta política con una propuesta de gestión del agua en el DF como parte de la cuenca del Valle de México.National planning based on drainage basins is part...
The treatment of yellow water (human urine) in a downflow fluidised bed reactor (DFFBR) was inves... more The treatment of yellow water (human urine) in a downflow fluidised bed reactor (DFFBR) was investigated to evaluate biological ureolysis and nutrient recovery. The reactor was operated at 30±4 °C in batch mode, and reaction time = 1 d. The average immobilised biomass (as volatile solids, IVS) in the reactor was 2.5±0.9 g L−1support, and specific ureolytic activity was 121 g Urea-N g−1 IVS d−1. The kinetic parameters were 0.152 mol L−1 (Km) and 8 mol g−1 IVS d−1 (Vmax). The ureolysis efficiency was 93.4% and chemical oxygen demand removal efficiency was 31.2%, while total ammonium nitrogen (NH4+-N) production rate was 7 g L−1 d−1 and phosphate removal reached 26%. Precipitates recovery during biological treatment was 1.72±0.8 g. These results suggest that the treatment of yellow water in a DFFBR is a viable option for partial recovery of N and P.
The growth of aquaculture as an industry has accelerated over the past decades; this has resulted... more The growth of aquaculture as an industry has accelerated over the past decades; this has resulted in environmental damages and low productivity of various crops. The need for increased disease resistance, growth of aquatic organisms, and feed efficiency has brought about the use of probiotics in aquaculture practices. The first application of probiotics occurred in 1986, to test their ability to increase growth of hydrobionts (organisms that live in water). Later, probiotics were used to improve water quality and control of bacterial infections. Nowadays, there is documented evidence that probiotics can improve the digestibility of nutrients, increase tolerance to stress, and encourage reproduction. Currently, there are commercial probiotic products prepared from various bacterial species such as Bacillus sp., Lactobacillus sp., Enterococcus sp., Carnobacterium sp., and the yeast Saccharomyces cerevisiae among others, and their use is regulated by careful management recommendations....
Revista Digital Universitaria (1607 - 6079). Vol. 14, No. 10 (2013), Oct 1, 2013
0 0 1 121 695 UNAM 5 1 815 14.0 Normal 0 false false false ES-MX JA X-NONE /* Style Definitions *... more 0 0 1 121 695 UNAM 5 1 815 14.0 Normal 0 false false false ES-MX JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-ansi-language:ES-MX; mso-fareast-language:ES-MX;} La planeacion por cuencas es sustancial al manejo sustentable del agua. En donde se genera se debe preservar y usar. A partir de este paradigma se plantean dos estrategias para la conservacion del recurso: una es aumentar la captacion y otra es reducir la extraccion. Y a partir de ellas se plantean acciones y se resaltan las tecnologias que hace falta desarrollar en Mexico para alcanzar la sustentabilidad. Es necesaria una politica publica para pasar del bombeo que es la unica tecnologia actual para manejar el agua a una variedad de tecnologias para incrementar su captacion, su uso eficiente, su tratamiento y su reuso. Se requiere conjuntar las politicas de manejo de agua, produccion de alimentos, de vivienda y de empleo para que con la participacion publica se alcance para todos un digno nivel de vida.
The growth of aquaculture as an industry has accelerated over the past decades; this has resulted... more The growth of aquaculture as an industry has accelerated over the past decades; this has resulted in environmental damages and low productivity of various crops. The need for increased disease resistance, growth of aquatic organisms, and feed efficiency has brought about the use of probiotics in aquaculture practices. The first application of probiotics occurred in 1986, to test their ability to increase growth of hydrobionts (organisms that live in water). Later, probiotics were used to improve water quality and control of bacterial infections. Nowadays, there is documented evidence that probiotics can improve the digestibility of nutrients, increase tolerance to stress, and encourage reproduction. Currently, there are commercial probiotic products prepared from various bacterial species such as Bacillus sp., Lactobacillus sp., Enterococcus sp., Carnobacterium sp., and the yeast Saccharomyces cerevisiae among others, and their use is regulated by careful management recommendations....
Separation of domestic effluents at the source and the utilization of low-flush toilets offer alt... more Separation of domestic effluents at the source and the utilization of low-flush toilets offer alternative approaches for developing efficient wastewater treatment systems while promoting energy generation through anaerobic digestion. This study focused on assessing toilet usage in Mexico and exploring the potential of anaerobic codigestion of brown water (feces) and toilet paper as influential factors in wastewater treatment systems. A survey was conducted on a representative sample of Mexicans to gather information on toilet usage frequency, toilet paper use and disposal practices, as well as the type and quantity of commercial disinfectants and pharmaceutical compounds they use or consume. The survey revealed that per capita toilet paper consumption is 2.9 kg annually, that 58 % of respondents do not dispose used paper in the toilet, and that about 47 % use two to three cleaning and disinfection products. Notably, 97 % of the sampled Mexican population expressed a willingness to transition to more eco-friendly toilet options. Subsequently, in a second step, the anaerobic codigestion of brown water with toilet paper was evaluated, demonstrating a relatively high production of volatile
fatty acids but low methane production. This suggests an efficient hydrolysis/acidogenesis process coupled with restrained methanogenesis, probably due to pH decrease caused by acidogenesis. This study underscores that toilet paper and brown water are potential suitable substrates for anaerobic co-digestion. Furthermore, it
sheds light on the behaviors of Mexican society regarding bathroom use and cleaning, contributing to the establishment of foundations for wastewater treatment systems with effluent separation at the source.
Las emulsiones multiples agua-en aceite-en agua (W1/O/W2) en el area ambiental se han propuesto p... more Las emulsiones multiples agua-en aceite-en agua (W1/O/W2) en el area ambiental se han propuesto para tratar aguas. Actualmente se ha sugerido entrampar un consorcio microbiano degradador de MTBE en el sistema de emulsiones multiples, para tratar agua contaminada con metil ter butil eter (MTBE), no obstante, es importante el uso de los materiales adecuados en la formulacion de la emulsion debido a que pueden interferir en la degradacion de MTBE. El objetivo de este estudio fue observar el consumo de los materiales que componen la emulsion multiple W1/O/W2 en presencia y ausencia de MTBE por el consorcio microbiano. Los materiales que se han propuesto para estabilizar la emulsion multiple W1/O/W2 son goma de mezquite (Prosopis laevigata), acido poliacrilico, aceite mineral ligero y Span 80. Se utilizaron cada uno de los anteriores compuestos por separado en una concentracion de 0.2% en microcosmos en ausencia y en presencia de MTBE, se cuantifico CO2 para advertir el consumo de los co...
This study is focused on the effect of thermo alkaline pretreatment on velocity of anaerobic hydr... more This study is focused on the effect of thermo alkaline pretreatment on velocity of anaerobic hydrolysis mesophilic and thermophilic of waste activated sludge (WAS), separating the hydrolysis of suspended solids (SS) and dissolved solids (SD). In order to research the hydrolysis of SS, the Sander’s surface model was used, and for the hydrolysis of SD, the Goel’s model of saturation was employed. The pretre tment increased the uperficial rea available for the enzymatic action, due to the reduction of the solids size. The effect of the pretreatment in the anaerobic digestion of the SD in thermophilic conditions, resulted in competitive inhibition over the anaerobic hydrolysis rate, whereas that in mesophilic conditions, resulted in non competitive inhibition. Mathematical simulation of SS to SD and methane consecutive reactions, showed that a 4 % increase in initial thermal-alkaline tr ated sludge di inished the inhibition of SD hydrolysis in the thermophilic anaerobic digestion.
The present research studies of mesophilic hydrolysis (AM) and stabilization under thermophilic m... more The present research studies of mesophilic hydrolysis (AM) and stabilization under thermophilic methanogenic conditions (MT) for a mixture of primary sludge (PS) and secondary sludge (SS) using two serial Upflow Anaerobic Sludge Blanket reactors (UASB). The AM and MT reactors were operated at 32 ± 2 °C and 56 ± 1 °C, respectively with different rates of PS:SS in the supply, without stir or recirculation at different hydraulic retention times (HRT). The AM reactor showed the optimal results in the stage V, HRT of 2 days, solid retention times (SRT) of 18.1 for a PS:SS rate of 50:50, and volumetric loading (Bv) of 3.6 kg DQO/m3.d., and it was observed a COD removal efficiency of 56.8%, soluble COD production of 48.3%, volatile suspended solids (VSS) removal of 68.6% using a hydrolysis rate of 0.16 kg/m3.d. The MT reactor showed the optimal stabilization for HRT on the 6th day of operation, methane (CH4) production of 107.7 mL CH4/ Kg VSSremoved, VSS removal of 66%, faecal coliform eli...
Aquatic plant biomass has been shown to have a great potential for biogas production. The use of ... more Aquatic plant biomass has been shown to have a great potential for biogas production. The use of ruminal fluid has been shown to improve the degradation of the lignocellulosic material with its conversion into volatile fatty acids (VFA) during a first phase of hydrolysis–acidogenesis. VFAs are important as the feedstock for methane and hydrogen production in a second phase process within a biorefinery. The objective of this work was to produce a high yield of VFA during a first phase of anaerobic hydrolysis–acidogenesis of Pistia stratiotes biomass assessing the effect of the use of rumen fluid as inoculum and of daily adjustment of pH in batch-operated reactors. One liter anaerobic reactors containing 15 gSV L−1 of P. stratiotes biomass were incubated at 30 ± 2 °C and agitated once a day. The inoculum concentration had no significant effect on the increase in VFA concentration and 20 % (V/V) was used in all treatments. The final average VFA concentration and conversion coefficients from VS to VFA in the inoculated treatment with no pH adjustment (T1) and with pH adjustment (T2) (1817 mgCOD L−1 and 0.1319 mgVFA mgVS−1, respectively) were significantly higher than those found in the treatment with no inoculum (T0). There were no significant differences between T0 and T1 in the VS degradation rate. In contrast, the degradation rate in T2 was significantly higher. Thus, the addition of ruminal fluid promoted the production of VFA, and the pH adjustment had no significant effect on this parameter but did influence the biomass degradation.
This study is focused on the e�ect of thermo alkaline pretreatment on velocity of anaerobic hydro... more This study is focused on the e�ect of thermo alkaline pretreatment on velocity of anaerobic hydrolysis mesophilic and thermophilic of waste activated sludge (WAS), separating the hydrolysis of suspended solids (SS) and dissolved solids (SD). In order to research the hydrolysis of SS, the Sander¿s surface model was used, and for the hydrolysis of SD, the Goel¿s model of saturation was employed. The pretreatment increased the superficial area available for the enzymatic action, due to the reduction of the solids size. The e�ect of the pretreatment in the anaerobic digestion of the SD in thermophilic conditions, resulted in competitive inhibition over the anaerobic hydrolysis rate, whereas that in mesophilic conditions, resulted in non competitive inhibition. Mathematical simulation of SS to SD and methane consecutive reactions, showed that a 4 % increase in initial thermal-alkaline treated sludge diminished the inhibition of SD hydrolysis in the thermophilic anaerobic digestion.
The kinetics of the acidogenic and methanogenic stages of lactose digestion were studied in two i... more The kinetics of the acidogenic and methanogenic stages of lactose digestion were studied in two independent upflow anaerobic sludge bed (UASB) reactors. The acidogenic reactor stage was fed on lactose (1 g/L) at several specific organic loading rates (SOLR) (0.2, 0.4, 0,8, 1 and 1.6 g COD/g VSS.d). At 1.0 g COD/VSS.d the acidogenic and methanogenic conversions were highest with acetate being 67% of total VFA (50% on a COD basis) while the COD degradation rate was minimal 0.2 g CODdeg/g VSS.d. The methanogenic reactor was fed on acetate-lactose mixtures (100,75, 50, 25, 0% acetate) at an OLR of 0.41 g COD/g VSS.d with the best performance at 50%. The results show that in order to control a two stage anaerobic process, the control strategies should be put on the acidogenic reactor in order to produce a fixed acetate percentage in the feed to the methanogenic reactor.
Bulletin of Environmental Contamination and Toxicology, 1999
) is a pesticide that belongs to the group of organochlorines. It has beenextensively used since ... more ) is a pesticide that belongs to the group of organochlorines. It has beenextensively used since the Second World War all over the world and, even though its useis banned or restricted in many countries because of its deleterious effects, it is stillcommonly found in the environment, especially in the soil, due to its strong adsorption tosolid particles, which results in a great persistency (EPA, 1986). Some investigationshave reported that the DDT present in the soil can be degraded in two years, while othershave found that the process can take from fifteen to twenty years or more (Alexander,1994).The degradation products of DDT are mainly the dechlorination products DDE and DDD.The pathway can be DDT → DDE → DDD, or from DDT to DDD directly. These routeshave not been completely established, even after 40 years of studies (Wayland et al.,1991). In anaerobic marine sediments DDE is readily dechlorinated to DDMU (Quensenet al., 1998).In less developed countries, the use of DDT still continues in order to control diseasessuch as malaria and dengue (Wayland et al., 1991; Cebrian, 1998). So far, no chemicalcompound has been found that brings together DDT’s properties and effectiveness. InMexico, the use of DDT is higher than in any other Latin American country (PAHO,1994). Mexico used about 1000 tons of DDT in 1992 (Sharpe, 1995). The production ofDDT in Mexico is mostly for its own use. Though production has diminished since 1970,it has remained stable since 1985 (Lopez-Carrillo et al., 1996). In a study carried out inthe state of Veracruz in Mexico, DDT and DDE were determined in the adipose tissue ofpeople. These compounds were present in all the cases analyzed and the highest levelswere found in a suburban zone. Average DDT concentration was 24.82 mg/kg, veryhigh compared to the results in other countries (Waliszewski et al., 1995).In recent years, there has been renewed research interest in DDT, since it has beenassociated with several health problems, including the increased risk of breast cancer inwomen and alterations in reproductive functions in men (Cebrian, 1998).DDT is a chlorinated organic compound that is highly resistant to degradation bybiological, photolithical and chemical means, given that its molecular structure containschlorinated aliphatic and aromatic structures that impart great chemical stability.Because of this, DDT is a recalcitrant, toxic, persistent pollutant (Kannan et al., 1992).This explains the current interest in developing bioremediation processes for thiscompound.Current bioremediation processes typically use aerobic bacteria to degrade petroleum andother chemical wastes by oxidation of the compounds. However, it has been observedthat anaerobic systems are often more capable of degrading chlorinated pollutants byreductive dechlorination (Leahy and Brown, 1994). Some compounds, such aspolychlorinated biphenyls (PCBs) can be initially dechlorinated and partially degraded by
Two stages anaerobic digestion of the organic fraction of municipal solid wastes (OFMSW) is propo... more Two stages anaerobic digestion of the organic fraction of municipal solid wastes (OFMSW) is proposed using a batch anaerobic trickling bed (BATB) reactor in the first hydrolysis and acidogenesis stage. At total solids loading of 135 g/L and reaction times around 30 days, total solids (ηTS) and chemical oxygen demand (ηCOD) removal efficiencies above 46% were obtained independently of pH (between 4.1 and 6.4). Dependent on pH were methane production, four times more at pH 6.4 than at 4.8 and four times more volatile fatty acids (VFA) production at 6.4 than at 4.1 and twice than at 4.8. Leachates generated in the BATB reactor were diluted with municipal wastewater and fed to an upflow anaerobic sludge blanket (UASB) reactor at volumetric organic loading rates from 11 to 28 g/L.d where 90% COD removal efficiencies (ηCOD) and 11.4 g CODCH4./L.d were obtained. Two stages anaerobic digestion results in high rates of solids removal and methane production (0.63 kWhr/kg TS fed).
Presencia UniversitariaLa planeación por cuencas es sustancial para el manejo sustentable del agu... more Presencia UniversitariaLa planeación por cuencas es sustancial para el manejo sustentable del agua. En donde se genera se debe preservar y usar. A partir de este paradigma se plantean dos estrategias para la conservación del recurso: una es aumentar la captación y otra es reducir la extracción. A partir de ellas se plantean acciones y se resaltan las tecnologías que hace falta desarrollar en México para alcanzar la sustentabilidad. Es necesaria una política pública para pasar del bombeo, que es la única tecnología actual para manejar el agua, a una variedad de tecnologías para incrementar su captación, uso eficiente, tratamiento y reuso. Hay que conjuntar las políticas de manejo de agua, producción de alimentos, de vivienda y empleo para que con la participación pública se alcance para todos un digno nivel de vida. Se ejemplifica esta política con una propuesta de gestión del agua en el DF como parte de la cuenca del Valle de México.National planning based on drainage basins is part...
The treatment of yellow water (human urine) in a downflow fluidised bed reactor (DFFBR) was inves... more The treatment of yellow water (human urine) in a downflow fluidised bed reactor (DFFBR) was investigated to evaluate biological ureolysis and nutrient recovery. The reactor was operated at 30±4 °C in batch mode, and reaction time = 1 d. The average immobilised biomass (as volatile solids, IVS) in the reactor was 2.5±0.9 g L−1support, and specific ureolytic activity was 121 g Urea-N g−1 IVS d−1. The kinetic parameters were 0.152 mol L−1 (Km) and 8 mol g−1 IVS d−1 (Vmax). The ureolysis efficiency was 93.4% and chemical oxygen demand removal efficiency was 31.2%, while total ammonium nitrogen (NH4+-N) production rate was 7 g L−1 d−1 and phosphate removal reached 26%. Precipitates recovery during biological treatment was 1.72±0.8 g. These results suggest that the treatment of yellow water in a DFFBR is a viable option for partial recovery of N and P.
The growth of aquaculture as an industry has accelerated over the past decades; this has resulted... more The growth of aquaculture as an industry has accelerated over the past decades; this has resulted in environmental damages and low productivity of various crops. The need for increased disease resistance, growth of aquatic organisms, and feed efficiency has brought about the use of probiotics in aquaculture practices. The first application of probiotics occurred in 1986, to test their ability to increase growth of hydrobionts (organisms that live in water). Later, probiotics were used to improve water quality and control of bacterial infections. Nowadays, there is documented evidence that probiotics can improve the digestibility of nutrients, increase tolerance to stress, and encourage reproduction. Currently, there are commercial probiotic products prepared from various bacterial species such as Bacillus sp., Lactobacillus sp., Enterococcus sp., Carnobacterium sp., and the yeast Saccharomyces cerevisiae among others, and their use is regulated by careful management recommendations....
Revista Digital Universitaria (1607 - 6079). Vol. 14, No. 10 (2013), Oct 1, 2013
0 0 1 121 695 UNAM 5 1 815 14.0 Normal 0 false false false ES-MX JA X-NONE /* Style Definitions *... more 0 0 1 121 695 UNAM 5 1 815 14.0 Normal 0 false false false ES-MX JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-ansi-language:ES-MX; mso-fareast-language:ES-MX;} La planeacion por cuencas es sustancial al manejo sustentable del agua. En donde se genera se debe preservar y usar. A partir de este paradigma se plantean dos estrategias para la conservacion del recurso: una es aumentar la captacion y otra es reducir la extraccion. Y a partir de ellas se plantean acciones y se resaltan las tecnologias que hace falta desarrollar en Mexico para alcanzar la sustentabilidad. Es necesaria una politica publica para pasar del bombeo que es la unica tecnologia actual para manejar el agua a una variedad de tecnologias para incrementar su captacion, su uso eficiente, su tratamiento y su reuso. Se requiere conjuntar las politicas de manejo de agua, produccion de alimentos, de vivienda y de empleo para que con la participacion publica se alcance para todos un digno nivel de vida.
The growth of aquaculture as an industry has accelerated over the past decades; this has resulted... more The growth of aquaculture as an industry has accelerated over the past decades; this has resulted in environmental damages and low productivity of various crops. The need for increased disease resistance, growth of aquatic organisms, and feed efficiency has brought about the use of probiotics in aquaculture practices. The first application of probiotics occurred in 1986, to test their ability to increase growth of hydrobionts (organisms that live in water). Later, probiotics were used to improve water quality and control of bacterial infections. Nowadays, there is documented evidence that probiotics can improve the digestibility of nutrients, increase tolerance to stress, and encourage reproduction. Currently, there are commercial probiotic products prepared from various bacterial species such as Bacillus sp., Lactobacillus sp., Enterococcus sp., Carnobacterium sp., and the yeast Saccharomyces cerevisiae among others, and their use is regulated by careful management recommendations....
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Papers by O. Monroy
fatty acids but low methane production. This suggests an efficient hydrolysis/acidogenesis process coupled with restrained methanogenesis, probably due to pH decrease caused by acidogenesis. This study underscores that toilet paper and brown water are potential suitable substrates for anaerobic co-digestion. Furthermore, it
sheds light on the behaviors of Mexican society regarding bathroom use and cleaning, contributing to the establishment of foundations for wastewater treatment systems with effluent separation at the source.
fatty acids but low methane production. This suggests an efficient hydrolysis/acidogenesis process coupled with restrained methanogenesis, probably due to pH decrease caused by acidogenesis. This study underscores that toilet paper and brown water are potential suitable substrates for anaerobic co-digestion. Furthermore, it
sheds light on the behaviors of Mexican society regarding bathroom use and cleaning, contributing to the establishment of foundations for wastewater treatment systems with effluent separation at the source.