Ammonia accumulation in biogas plants reactors is becoming more frequently encountered, resulting... more Ammonia accumulation in biogas plants reactors is becoming more frequently encountered, resulting in reduced methane (CH4) production. Ammonia toxicity occurs when N-rich substrates represent a significant part of the biogas plant’s feedstock. The aim of this study was to develop an estimation method for the effect of ammonia toxicity on the CH4 production of biogas plants. Two periods where a biogas plant operated at 3200 mg·L−1 (1st period) and 4400 mg·L−1 (2nd period) of ammonium nitrogen (NH4+–N) were examined. Biomethane potentials (BMPs) of the individual substrates collected during these periods and of the mixture of substrates with the weight ratio used by the biogas plant under different ammonia levels (2000–5200 mg·L−1 NH4+–N) were determined. CH4 production calculated from the substrates’ BMPs and the quantities used of each substrate by the biogas plant was compared with actual CH4 production on-site. Biogas plant’s CH4 production was 9.9% lower in the 1st and 20.3% in t...
The environmental planning of Magnesia Prefecture is studied in this work, aiming at the assessme... more The environmental planning of Magnesia Prefecture is studied in this work, aiming at the assessment of the environmental quality and the determination of the most appropriate objectives and priorities, for the achievement of the highest environmental protection level in the target area. Examination of air pollution sources showed that atmospheric pollution is mainly attributed to point sources, while the contribution of diffusion sources is negligible. In Pagasitikos Gulf, seawater pollution is increased, especially in the bay of Volos, in places where treated domestic and industrial wastewaters are discharged, and intense marine activities are developed (harbor of Volos). Moreover, significant pollution results fiom human activities such as drainage fiom rural areas, discharge of raw industrial wastewaters fiom olive processing units, and wastes from ships navigating in the area. Other important pollution problems include fiesh water salination in coastal areas, and high concentrat...
This work aims to identify the potential biomass resources produced in the area of the Central Ma... more This work aims to identify the potential biomass resources produced in the area of the Central Macedonia Region, in Northern Greece, in order to contribute to the efforts to achieve national targets for renewable energy sources. Specific objectives included the evaluation of the biomass amounts in each regional unit, the measurement of their characteristics and properties, and the investigation of their utilization potential. According to this survey, a total of 1.33 million tonnes of fresh biomass residues are produced in the Greek Central Macedonia Region. The utilization potential of available biomass resources may be evaluated according to the quality characteristics of the various types of biomass based on the results of laboratory tests and classified in the following ranking in descending order: peach and olive stone, cotton residues, almond shell, olive cake, pressed grape skins, peach pulp and peach and potato peels. The residues from oil production and cotton mill residues are of high importance. Agricultural residues remaining in the farming areas, such as olive and peach branches, represent another challenging biomass source. Furthermore, according to the survey for each regional unit, there is a significant number of biomass types that could be utilized, after appropriate management. An efficient management plan should be based on the use of biomass resources with a regular production regime over the year, such as manure or potato residues, combined with or supported by the sequential use of various other residues produced through the year, on a temporary basis. Thus the presence of different types of biomass resources in the specific area, with seasonal variability, could justify the continuous availability of raw materials all year round.
Abstract The removal of toxic materials is becoming ever more critical due to diminishing water r... more Abstract The removal of toxic materials is becoming ever more critical due to diminishing water resources, increasing wastewater disposal costs, and stricter discharge regulations that have lowered permissible contaminant levels in waste streams. The present work presents an overview of various techniques (such as chemical precipitation, electrochemical treatment, coagulation—flocculation, flotation, membrane filtration, adsorption and ion exchange, catalytic oxidation, phytoremediation, and biodegradation processes) for the removal of toxic materials from water and wastewater, including their advantages, limitations, and applications. Secure management methods of wastes containing toxic materials, including waste minimization, recycling, degradation, vitrification, and stabilization, are also summarized and annotated. The chapter is completed with case studies for potential application of toxic materials removal techniques in water and wastewater treatment.
Four microalgae species were evaluated for their bioremediation capacity of anaerobic digestion e... more Four microalgae species were evaluated for their bioremediation capacity of anaerobic digestion effluent (ADE) rich in ammonium nitrogen, derived from a biogas plant. Chlorella vulgaris, Chlorella sorokiniana, Desmodesmus communis and Stichococcus sp. were examined for their nutrient assimilation efficiency, biomass production and composition through their cultivation in 3.7% v/v ADE; their performance was compared with standard cultivation media which consisted in different nitrogen sources, i.e., BG-11NO3 and BG-11ΝH4 where N-NO3 was replaced by N-NH4. The results justified ammonium as the most preferable source of nitrogen for microalgae growth. Although Stichococcus sp. outperformed the other 3 species in N-NH4 removal efficiency both in BG-11NH4 and in 3.7% ADE (reaching up to 90.79% and 69.69% respectively), it exhibited a moderate biomass production when it was cultivated in diluted ADE corresponding to 0.59 g/L, compared to 0.89 g/L recorded by C. vulgaris and 0.7 g/L by C. ...
The aim of this paper was to evaluate the characteristics and the energy potential for the methan... more The aim of this paper was to evaluate the characteristics and the energy potential for the methane production of fine screenings collected from the primary stage of a municipal wastewater treatment plant, and assess the impact on the properties and the oxygen demand of the aqueous effluents downstream from the sieves. Commercial filter bags with sieve openings of 3000, 1250, 1000, and 300 μm were used for the collection of screenings following a measurement of their biochemical methane potential. It was revealed that solid fractions from the sieves with a large size presented a high net methane production capacity exceeding 900 mL/g VS, but the gas production rate was rather slow, requiring a long time to reach the final value. However, cumulative solid fractions containing particles with a size larger than 300 μm had a lower net methane production, about 700 mL/g VS, but with a faster rate, resulting in almost 80% of the total volume released in 30 days. Aqueous samples downstream ...
1 Sector of Industrial Management & Operations Research, School of Mechanical Engineering, Nation... more 1 Sector of Industrial Management & Operations Research, School of Mechanical Engineering, National Technical University of Athens, 15780, Athens, Greece 2Laboratory of Heat Transfer and Environmental Engineering, Department of Mechanical Engineering, ...
The aim of this work was to examine the ecotoxicity of reclaimed wastewater by the use of bioassa... more The aim of this work was to examine the ecotoxicity of reclaimed wastewater by the use of bioassays and the determination of immunological parameters. Secondary and tertiary mucicipal wastewater samples were examined for their physicochemical and microbiological characteristics as well as for their endotoxin concentrations. The ecotoxicological characteristics were assessed by a battery of bioassays, using Vibrio fischeri, Daphnia magna and Tetrahymena thermophilla as test species and phytotoxicity. The mitogenic responses of mouse splenocytes were as well used as bioassay. The cytokines of IL-1, IL-2, IL-10, IFNγ and TNFα, were also determined in the supernatant of splenocyte cultures and served as molecular biomarkers. All bioassays exhibited decrease of the ecotoxicological responses after tertiary treatment. However, mitogenic responses were proved to be more sensitive. IL-1 increased, while IL-2 production was unaffected. The fact that IL-10 production increased in response to ...
Wastewater treatment plants have been traditionally developed for the aerobic degradation of effl... more Wastewater treatment plants have been traditionally developed for the aerobic degradation of effluent organic matter, and are associated with high energy consumption. The adoption of sustainable development targets favors the utilization of every available energy source, and the current work aims at the identification of biomethane potential from non-conventional sources derived from municipal wastewater treatment processes. Byproducts derived from the primary treatment process stage were collected from four sewage treatment plants in Greece with great variation in design capacity and servicing areas with wide human activities, affecting the quality of the influents and the corresponding primary wastes. The samples were characterized for the determination of their solids and fats content, as well as the concentration of leached organic matter and nutrients, and were subjected to anaerobic digestion treatment for the measurement of their biomethane production potential according to s...
ABSTARCT The aim of this work was the study of the combination of an inorganic pre-polymerized co... more ABSTARCT The aim of this work was the study of the combination of an inorganic pre-polymerized coagulant (PACl) with ferric species and polysilicic acid in various Al/Fe/Si and OH/Al molar ratios, and two polymerization techniques for the production of a unique reagent representing a coagulant, more efficient than commercial PACl-18 and laboratory prepared PACllab for water or wastewater treatment. A number of coagulants were prepared and were examined by jar tests for the treatment of simulated water; turbidity and UV254nm absorbance were measured in the treated water. PSiFAC1.5:10:15 prepared by co-polymerization was found to be the most efficient coagulant from all the tested compounds. Low coagulant doses, about 2 mg/L were required for the reduction of turbidity values to lower than 1 NTU; furthermore, PSiFAC1.5:10:15 resulted in very low residual aluminum concentration of about 140μg Al/L. The most effective coagulant obtained was also used for the treatment of tannery wastewa...
Simple and low-cost field systems called biobeds have been successfully developed in Sweden to re... more Simple and low-cost field systems called biobeds have been successfully developed in Sweden to reduce the environmental pollution caused by pesticides. Although these systems have been efficiently used for the treatment of a broad range of wastewaters worldwide, however, their utilization for olive oil mill wastewaters (ΟMWW) treatment is limited. The aim of this study was the examination of a pilot soil tank of 1 m3 (biobed) operation for treatment, purification, and detoxification of a highly loaded olive oil wastewater effluent and the determination of the appropriate mixture of filling material consisted of compost and soil and the corresponding bed layer thickness for the optimum removal capacity of pollutants. A handmade irrigation system was developed to inject olive mill wastewater onto the biobed. Raw and effluent samples were collected in a feed and a storage tank, respectively. The effluent from the storage tank was recycled to the inlet of the system and the operation wa...
As water bodies are being severely stressed due to climate change conditions and growing populati... more As water bodies are being severely stressed due to climate change conditions and growing populations, special attention must be given to areas experiencing water scarcity problems. The Mediterranean area countries are suffering from water scarcity problems jeopardizing the sustainability of the local ecosystems. At the same time, more than 50% of the urban water being supplied in these countries, is being lost through leaks and breaks occurring in the water distribution systems mainly due to lack of efficient water losses reduction strategies. In order to guarantee sufficient quantities of good quality water, water utilities must apply water auditing and water losses control methods. International Water Association (IWA) developed a WB assessment methodology based on a very detailed handbook including 170 water system PIs, based on 232 system variables that need to be regularly monitored. Trying to implement the IWA methodology many practical problems appeared regarding unreliable o...
Ammonia accumulation in biogas plants reactors is becoming more frequently encountered, resulting... more Ammonia accumulation in biogas plants reactors is becoming more frequently encountered, resulting in reduced methane (CH4) production. Ammonia toxicity occurs when N-rich substrates represent a significant part of the biogas plant’s feedstock. The aim of this study was to develop an estimation method for the effect of ammonia toxicity on the CH4 production of biogas plants. Two periods where a biogas plant operated at 3200 mg·L−1 (1st period) and 4400 mg·L−1 (2nd period) of ammonium nitrogen (NH4+–N) were examined. Biomethane potentials (BMPs) of the individual substrates collected during these periods and of the mixture of substrates with the weight ratio used by the biogas plant under different ammonia levels (2000–5200 mg·L−1 NH4+–N) were determined. CH4 production calculated from the substrates’ BMPs and the quantities used of each substrate by the biogas plant was compared with actual CH4 production on-site. Biogas plant’s CH4 production was 9.9% lower in the 1st and 20.3% in t...
The environmental planning of Magnesia Prefecture is studied in this work, aiming at the assessme... more The environmental planning of Magnesia Prefecture is studied in this work, aiming at the assessment of the environmental quality and the determination of the most appropriate objectives and priorities, for the achievement of the highest environmental protection level in the target area. Examination of air pollution sources showed that atmospheric pollution is mainly attributed to point sources, while the contribution of diffusion sources is negligible. In Pagasitikos Gulf, seawater pollution is increased, especially in the bay of Volos, in places where treated domestic and industrial wastewaters are discharged, and intense marine activities are developed (harbor of Volos). Moreover, significant pollution results fiom human activities such as drainage fiom rural areas, discharge of raw industrial wastewaters fiom olive processing units, and wastes from ships navigating in the area. Other important pollution problems include fiesh water salination in coastal areas, and high concentrat...
This work aims to identify the potential biomass resources produced in the area of the Central Ma... more This work aims to identify the potential biomass resources produced in the area of the Central Macedonia Region, in Northern Greece, in order to contribute to the efforts to achieve national targets for renewable energy sources. Specific objectives included the evaluation of the biomass amounts in each regional unit, the measurement of their characteristics and properties, and the investigation of their utilization potential. According to this survey, a total of 1.33 million tonnes of fresh biomass residues are produced in the Greek Central Macedonia Region. The utilization potential of available biomass resources may be evaluated according to the quality characteristics of the various types of biomass based on the results of laboratory tests and classified in the following ranking in descending order: peach and olive stone, cotton residues, almond shell, olive cake, pressed grape skins, peach pulp and peach and potato peels. The residues from oil production and cotton mill residues are of high importance. Agricultural residues remaining in the farming areas, such as olive and peach branches, represent another challenging biomass source. Furthermore, according to the survey for each regional unit, there is a significant number of biomass types that could be utilized, after appropriate management. An efficient management plan should be based on the use of biomass resources with a regular production regime over the year, such as manure or potato residues, combined with or supported by the sequential use of various other residues produced through the year, on a temporary basis. Thus the presence of different types of biomass resources in the specific area, with seasonal variability, could justify the continuous availability of raw materials all year round.
Abstract The removal of toxic materials is becoming ever more critical due to diminishing water r... more Abstract The removal of toxic materials is becoming ever more critical due to diminishing water resources, increasing wastewater disposal costs, and stricter discharge regulations that have lowered permissible contaminant levels in waste streams. The present work presents an overview of various techniques (such as chemical precipitation, electrochemical treatment, coagulation—flocculation, flotation, membrane filtration, adsorption and ion exchange, catalytic oxidation, phytoremediation, and biodegradation processes) for the removal of toxic materials from water and wastewater, including their advantages, limitations, and applications. Secure management methods of wastes containing toxic materials, including waste minimization, recycling, degradation, vitrification, and stabilization, are also summarized and annotated. The chapter is completed with case studies for potential application of toxic materials removal techniques in water and wastewater treatment.
Four microalgae species were evaluated for their bioremediation capacity of anaerobic digestion e... more Four microalgae species were evaluated for their bioremediation capacity of anaerobic digestion effluent (ADE) rich in ammonium nitrogen, derived from a biogas plant. Chlorella vulgaris, Chlorella sorokiniana, Desmodesmus communis and Stichococcus sp. were examined for their nutrient assimilation efficiency, biomass production and composition through their cultivation in 3.7% v/v ADE; their performance was compared with standard cultivation media which consisted in different nitrogen sources, i.e., BG-11NO3 and BG-11ΝH4 where N-NO3 was replaced by N-NH4. The results justified ammonium as the most preferable source of nitrogen for microalgae growth. Although Stichococcus sp. outperformed the other 3 species in N-NH4 removal efficiency both in BG-11NH4 and in 3.7% ADE (reaching up to 90.79% and 69.69% respectively), it exhibited a moderate biomass production when it was cultivated in diluted ADE corresponding to 0.59 g/L, compared to 0.89 g/L recorded by C. vulgaris and 0.7 g/L by C. ...
The aim of this paper was to evaluate the characteristics and the energy potential for the methan... more The aim of this paper was to evaluate the characteristics and the energy potential for the methane production of fine screenings collected from the primary stage of a municipal wastewater treatment plant, and assess the impact on the properties and the oxygen demand of the aqueous effluents downstream from the sieves. Commercial filter bags with sieve openings of 3000, 1250, 1000, and 300 μm were used for the collection of screenings following a measurement of their biochemical methane potential. It was revealed that solid fractions from the sieves with a large size presented a high net methane production capacity exceeding 900 mL/g VS, but the gas production rate was rather slow, requiring a long time to reach the final value. However, cumulative solid fractions containing particles with a size larger than 300 μm had a lower net methane production, about 700 mL/g VS, but with a faster rate, resulting in almost 80% of the total volume released in 30 days. Aqueous samples downstream ...
1 Sector of Industrial Management & Operations Research, School of Mechanical Engineering, Nation... more 1 Sector of Industrial Management & Operations Research, School of Mechanical Engineering, National Technical University of Athens, 15780, Athens, Greece 2Laboratory of Heat Transfer and Environmental Engineering, Department of Mechanical Engineering, ...
The aim of this work was to examine the ecotoxicity of reclaimed wastewater by the use of bioassa... more The aim of this work was to examine the ecotoxicity of reclaimed wastewater by the use of bioassays and the determination of immunological parameters. Secondary and tertiary mucicipal wastewater samples were examined for their physicochemical and microbiological characteristics as well as for their endotoxin concentrations. The ecotoxicological characteristics were assessed by a battery of bioassays, using Vibrio fischeri, Daphnia magna and Tetrahymena thermophilla as test species and phytotoxicity. The mitogenic responses of mouse splenocytes were as well used as bioassay. The cytokines of IL-1, IL-2, IL-10, IFNγ and TNFα, were also determined in the supernatant of splenocyte cultures and served as molecular biomarkers. All bioassays exhibited decrease of the ecotoxicological responses after tertiary treatment. However, mitogenic responses were proved to be more sensitive. IL-1 increased, while IL-2 production was unaffected. The fact that IL-10 production increased in response to ...
Wastewater treatment plants have been traditionally developed for the aerobic degradation of effl... more Wastewater treatment plants have been traditionally developed for the aerobic degradation of effluent organic matter, and are associated with high energy consumption. The adoption of sustainable development targets favors the utilization of every available energy source, and the current work aims at the identification of biomethane potential from non-conventional sources derived from municipal wastewater treatment processes. Byproducts derived from the primary treatment process stage were collected from four sewage treatment plants in Greece with great variation in design capacity and servicing areas with wide human activities, affecting the quality of the influents and the corresponding primary wastes. The samples were characterized for the determination of their solids and fats content, as well as the concentration of leached organic matter and nutrients, and were subjected to anaerobic digestion treatment for the measurement of their biomethane production potential according to s...
ABSTARCT The aim of this work was the study of the combination of an inorganic pre-polymerized co... more ABSTARCT The aim of this work was the study of the combination of an inorganic pre-polymerized coagulant (PACl) with ferric species and polysilicic acid in various Al/Fe/Si and OH/Al molar ratios, and two polymerization techniques for the production of a unique reagent representing a coagulant, more efficient than commercial PACl-18 and laboratory prepared PACllab for water or wastewater treatment. A number of coagulants were prepared and were examined by jar tests for the treatment of simulated water; turbidity and UV254nm absorbance were measured in the treated water. PSiFAC1.5:10:15 prepared by co-polymerization was found to be the most efficient coagulant from all the tested compounds. Low coagulant doses, about 2 mg/L were required for the reduction of turbidity values to lower than 1 NTU; furthermore, PSiFAC1.5:10:15 resulted in very low residual aluminum concentration of about 140μg Al/L. The most effective coagulant obtained was also used for the treatment of tannery wastewa...
Simple and low-cost field systems called biobeds have been successfully developed in Sweden to re... more Simple and low-cost field systems called biobeds have been successfully developed in Sweden to reduce the environmental pollution caused by pesticides. Although these systems have been efficiently used for the treatment of a broad range of wastewaters worldwide, however, their utilization for olive oil mill wastewaters (ΟMWW) treatment is limited. The aim of this study was the examination of a pilot soil tank of 1 m3 (biobed) operation for treatment, purification, and detoxification of a highly loaded olive oil wastewater effluent and the determination of the appropriate mixture of filling material consisted of compost and soil and the corresponding bed layer thickness for the optimum removal capacity of pollutants. A handmade irrigation system was developed to inject olive mill wastewater onto the biobed. Raw and effluent samples were collected in a feed and a storage tank, respectively. The effluent from the storage tank was recycled to the inlet of the system and the operation wa...
As water bodies are being severely stressed due to climate change conditions and growing populati... more As water bodies are being severely stressed due to climate change conditions and growing populations, special attention must be given to areas experiencing water scarcity problems. The Mediterranean area countries are suffering from water scarcity problems jeopardizing the sustainability of the local ecosystems. At the same time, more than 50% of the urban water being supplied in these countries, is being lost through leaks and breaks occurring in the water distribution systems mainly due to lack of efficient water losses reduction strategies. In order to guarantee sufficient quantities of good quality water, water utilities must apply water auditing and water losses control methods. International Water Association (IWA) developed a WB assessment methodology based on a very detailed handbook including 170 water system PIs, based on 232 system variables that need to be regularly monitored. Trying to implement the IWA methodology many practical problems appeared regarding unreliable o...
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