Nutrient Limitation in a Coastal System Influenced by Mussel Farming, River Outflow and On-shore Circulation of Waters Abstract The aim of this study was to investigate nutrient availability for mussel growth in the coastal waters of NW Thessaloniki Gulf (Greece). Nutrient and chlorophyll-a measurements were taken on a monthly basis during 2014–15, along an experimental line of mussels growing in suspension and in the open sea, outside the area of intensive mussel farming. The results are based on the calculation of N:P ratio, f = NO3−-N/(NO3−-N + NH4+-N) ratio and chlorophyll-a measurements. N:P ratio was high throughout the year, showing phosphate limitation, while the f ratio revealed low values of ‘new’ nitrogen entering the system (input of nitrate). According to chlorophyll-a measurements, the coastal waters are occasionally oligotrophic. Size fractionation revealed that phytoplankton cells were mostly picoplankton (<0.45 μm). Productivity in the region decreased during the summer when repeated on-shore circulation of waters is unfavorable for external sources of nutrients, resulting in limited nutrient availability for phytoplankton growth and thus, posing a risk for reduced mussel production.

Assessing Oil Content of Microalgae Grown in Industrial Energetic-Laden Wastewater Abstract Industrial ammunition facilities generate wastewater containing different energetic compounds and nitrogen species. Our previous studies showed that some of these untreated wastewater streams can be mixed at a specific ratio to grow microalgae. In this study, four different untreated wastewater samples from an industrial ammunition facility were mixed and used as a culture media for microalgae, Scenedesmus obliquus ATCC®11477, in 100 L raceway reactors. The main objective of the study was to test the effect of growth parameters (light penetration, nutrient availability and retention times) on the oil content of microalgae in a semi-continuous setting. The raceway reactors were operated under 68–95 μmol/m2/s of light intensity for a 14:10 h light:dark photoperiod, and 60 rpm mixing paddle speed. Continuous monitoring of pH and temperature of the growth medium, periodic analysis of cell density and dry weight of microalgae, and analysis of the medium’s nutrient contents were performed. Biomass harvesting from the raceway reactors was conducted weekly, and the harvested algal biomass was tested for its oil content using an ethanol extraction method. Results showed that nitrogen starvation increased the oil production from 13% to 29% of oil based on the dry weight of biomass, whereas no increment in oil or biomass production was evidenced with the increase of light penetration for the two different retention times tested. This study provided significant information towards microalgae growth in energetic-laden wastewater streams. This study also showed that wastewaters from industrial ammunition facilities can be reused for culturing microalgae, which can be utilized for renewable energy production.

Can Deliberative Approaches Make the Difference in Groundwater Economics and Management? Some First Evidence Abstract Deliberative monetary valuation (DMV) has emerged as a means to address the shortcomings of conventional stated preference techniques in the context of cost - benefit analysis. Especially for environmental goods or services that are complex or less familiar to participants and the community’s understanding with respect to non-market valuation is generally poor, DMV may be beneficial. This paper endeavours to contribute to the literature by exploring, for the first time, the role of information sharing, deliberation and storytelling on respondents’ values, beliefs and perceptions about groundwater resources. For this purpose, participants in a contingent valuation (CV) survey were invited to attend deliberative workshops, held after two months from the CV survey. The results indicate that the deliberation process has the ability to change participants’ perceptions by revealing values that were previously implicit, by helping them overcome cognitive barriers and by exposing them to a more diverse set of knowledge, arguments and opinions through group discussions. Overall, there is strong evidence that deliberation approaches could lead participants to better-informed choices, and consequently, to more sustainable, robust, and socially acceptable policy pathways for groundwater resources.

Comparison of Hydrographic Survey and Satellite Bathymetry in Monitoring Kerkini Reservoir Storage Abstract This paper investigates two mapping methods for Kerkini reservoir bottom, in order to study the morphology and the evolution of deposits at the reservoir. The methods are the hydrographic and the satellite bathymetry. The hydrographic method incorporates the geodetic satellite technology with sonar system for mapping the bottom relief, while the satellite bathymetry extracts the depths using the information from the spectral bands of a satellite image. The satellite Worldview-2 was used in this study. The milestones for the Kerkini reservoir were the years 1952 and 1982, where the construction of the west dike changed the hydrological regime. After these changes, bottom surveys of the reservoir were carried out in 1962 and 1984 and charts were produced. Based on these diagrams, deposition rates are calculated and volumes are compared over the years till the recent mapping in 2014. The digital bathymetry models, obtained from the implementation of hydrography and satellite bathymetry, are compared to each other. Furthermore, the development of new methods for the determination of volume and deposition rate can contribute to the optimal management of such water systems and the creation of a sustainability index for the reservoir.

Removal of COD from Industrial Biodiesel Wastewater Using an Integrated Process: Electrochemical-Oxidation with IrO 2 -Ta 2 O 5 /Ti Anodes and Chitosan Powder as an Adsorbent Abstract The production of biodiesel is an energy and water-intensive process that produces wastewater with high concentrations of COD, BOD, and FOG. Conventional treatment processes are not capable of treating contaminants and pollutants in biodiesel wastewater to satisfactory concentrations, and hence, advanced treatment processes are necessary. Untreated discharge of biodiesel wastewater results in additional costs during the production of biodiesel when penalties and fines are applied. In this research, a lab-scale integrated treatment process was used to investigate the successful abatement of contaminants, COD, BOD and FOG, present in industrial biodiesel wastewater. The integrated treatment process consisted of three consecutive steps: acidification, electrochemical oxidation, and adsorption. Acidification as a pre-treatment occurred at a pH of 2. Electrochemical oxidation using IrO2-Ta2O5/Ti anodes at a current density of 1 mA/cm2 and NaCl concentration of 0.08 M was followed by three consecutive adsorption stages using Chitosan powder at a concentration of 4.5 g/L. The experimental results show that the integrated treatment process could reduce COD, BOD and FOG levels by 94%, 86% and 95%, respectively. The treated effluent complies with local industrial effluent discharge standards, which could be disposed of safely without further treatment.

Removal of As(III) from Synthetic Groundwater Using Fe-Mn Bimetal Modified Kaolin Clay: Adsorption Kinetics, Isotherm and Thermodynamics Studies Abstract The removal efficiency of As(III) by kaolin clay modified by Fe-Mn bimetal oxides was successfully evaluated. Modification of kaolin clay by Fe-Mn oxides increased the surface area of the kaolin clay from 19.2 to 29.8 m2/g and further decreased the pore diameter from 9.54 to 8.5 nm. As(III) removal efficiency was optimum at pH < 8 and was inhibited at pH >8. The adsorption isotherm data fitted well to Langmuir adsorption isotherm model with a maximum adsorption capacity of 2.93 mg/g at initial As(III) concentration range of 1 to 30 mg/L. The adsorption kinetics data was described better by pseudo-second order of reaction kinetics indicating that As(III) sorption occurred via chemisorption. Thermodynamics studies revealed that As(III) adsorption occurs spontaneously and the reaction is exothermic in nature. Compared to other reported adsorbents, Fe-Mn bimetal kaolin showed higher adsorption capacity making it a suitable candidate for As(III) removal from groundwater.

Water Distillation Extraction of Essential Oil from Sideritis Raeseri Herb Abstract Water distillation extraction is a well known and popular method for obtaining essential oils from medicinal and aromatic herbs. Additionally, it represents an environmentally friendly process. In the current work, Sideritis raeseri, also known as mountain tea herb, is used to attain essential oils by means of Clevenger apparatus exploiting water as extracting solvent. Essential oils are recognized for their applications in folk medicine. The Sideritis herbs are widely distributed in Mediterranean regions and the Balkans (Albania, Greece and Bulgaria). The primary goal of the present work is to utilize an eco-friendly process, i.e., hydro-distillation to obtain essential oils from Sideritis raesieri. Secondly, to identify the main chemical components in the essential oils of Sideritis herbs by utilizing spectral characterization by means of FTIR spectroscopy. Several samples were considered for the water distillation extraction of Sideritis herbs from different localities of southern Albania, i.e., Zagori (Gjirokastra), Dry Mountain (Korҫa) and Tomorr Mountain (Korҫa). FTIR analyses indicated presence of alpha- and beta-pinene, and bicyclogermacrene as main chemical constituents in the essential oil samples. FTIR spectra featured signals in the range 1437–1374 cm−1 and 1637 cm−1 attributed to bicyclogermacrene, and alpha- and beta-pinene, respectively, in good agreement with reported FTIR relevant studies.

Comparative Analysis between Morphometry and Geo-Environmental Factor Based Soil Erosion Risk Assessment Using Weight of Evidence Model: a Study on Jainti River Basin, Eastern India Abstract Assessment of spatial soil erosion risk is a viable effort signifying the needs of conservation measures due to the deterioration of land as well as soil quality degradation at various scales. Among several non-quantitative approaches regarding erosion risk prediction, watershed morphometry and other geo-environmental parameter based assessments were performed largely and separately which showed varied results. In the present work, using 15 morphometric and 13 geo-environmental parameters, spatial soil erosion risk was modelled in order to inspect the performances and consistency of both approaches in predicting Spatial Soil Erosion Risk (SSER). Field site erosion patch inventory (a total of 164 erosion patches), google earth imagery and a probabilistic model, i.e., Weight of Evidence (WoE) enabled the analysis. Training patches (115 patches) were used to model the SSER while validation patches (49 patches) were used to assess the consistency of model output. Both approaches quantify 25.41% and 20.18% of the area to high to very high susceptibility class, separately. The contribution of each factor of both parameter groups in risk predicting was analysed through Map Removal Sensitivity Analysis (MRSA). Further, the results of performance were evaluated through Repetitive Operator Choice (ROC) curve (success rate and prediction rate curves) measuring Area Under Curve (AUC). The success and prediction rate curves show that when considering morphometric parameters, the AUC is 0.775 and 0.729, respectively, whereas in the case of geo-environmental parameters, AUC = 0.892 and 0.878 accordingly. This reveals the better consistency of geo-environmental parameters in context with the spatial erosion risk zoning in the present scenario.

Innovative Biogeochemical Cover to Mitigate Landfill Gas Emissions: Investigation of Controlling Parameters Based on Batch and Column Experiments Abstract Municipal solid waste (MSW) landfills generate different gases mainly methane (CH4) and carbon dioxide (CO2) during the process of waste decomposition. Modern landfills are provided with gas collection systems, however, significant amount of landfill gas (LFG) escapes into the atmosphere, making landfills one of the largest anthropogenic sources of CH4 and CO2 emissions. Several researchers have investigated various alternative landfill cover systems, such as biocovers, in order to mitigate CH4 transport across landfill covers by enhancing microbial CH4 oxidation. In recent years, biochar as an organic amendment has shown promise in enhanced microbial oxidation due to its inert/stable chemical nature, high surface area, high internal porosity, and high moisture holding capacity. However, in all these efforts, little regard is given to the CO2 that still escapes into the atmosphere in undesirable amounts. The current study introduces the concept of biogeochemical cover, which uses steel slag in conjunction with biochar-amended soil to mitigate fugitive emissions from a landfill. The current study compares the CO2 sequestration potential of steel slag, mainly basic oxygen furnace (BOF) slag under various environmental conditions that may prevail in the landfill cover. BOF slag shows significant CO2 sequestration potential under variable conditions including moisture, temperature, gas flow conditions, and BOF slag type and particle size. The results suggest that the use of BOF slag could be a cost effective and green solution to the problems of fugitive LFG emissions.

Kinetics of Reductive Degradation of 2,4-dinitroanisole (DNAN) Using Mg-Based Bimetals Abstract Technology advancements and modern use of explosives have led to the development of insensitive munitions such as 2,4-dinitroanisole (DNAN). Treatment systems using zero-valent iron (ZVI) and Fe-based bimetals are well-known, however, Mg-based bimetals can be advantageous over iron because of the more negative reduction potential and relative insensitivity to pH conditions. This work reports on the use of ZVMg and Mg-bimetals (Mg/Cu, Mg/Ni, Mg/Zn) to treat pure compound aqueous solutions and wastewater containing DNAN. Kinetic experiments were carried out in bench-scale batch reactors at unadjusted initial pH, 0.5% solids-to-liquid ratio (S/L), and 10:1 Mg to catalytic metal ratio. The results, modelled with a pseudo-first order kinetic expression, are used to determine reaction rate constants via nonlinear regression. For pure DNAN aqueous solutions, the pseudo-first order kinetic rate constants are 0.119, 0.102, 0.020, and 0.009 min−1 for Mg/Cu, Mg/Zn, Mg/Ni, and ZVMg, respectively. Reaction rate constants for DNAN wastewater are 0.114, 0.046, and 0.021 min−1 for Mg/Cu, Mg/Zn and Mg/Ni, respectively. Parametric studies investigated the impact of catalytic metal, reagent dose, and initial pH on DNAN degradation. Reagent dose levels tested were 0.25, 0.50 and 0.75% S/L. Initial pH, lowered with acetic acid (pH range 3.3–4.0), significantly enhanced reaction rates of all bimetal pairs and ZVMg yielding half-lives between 0.7–1.4 min. The bimetal pair showing the fastest kinetics at unadjusted initial pH, Mg/Cu, was characterized in constant temperature experiments. Under identical conditions (unadjusted initial pH, 0.5% S/L, 10:1 Mg: Cu), the activation energy of DNAN degradation by Mg/Cu is 8.47 kJ/mol.