Field application of farmstead runoff to vegetated filter strips: surface and subsurface water quality assessment

Farmstead runoff poses significant environmental impacts to ground and surface waters. Three vegetated filter strips were assessed for the treatment of dairy farmstead runoff at the soil surface and subsurface at 0.3- or 0. 46-m and 0. 76-m depths for numerous storm events. A medium-sized Michigan dairy was retrofitted with two filter strips on sandy loam soil and a third filter strip was implemented on a small Michigan dairy with sandy soil to collect and treat runoff from feed storage, manure storage, and other impervious farmstead areas. All filter strips were able to eliminate surface runoff via infiltration for all storm events over the duration of the study, eliminating pollutant contributions to surface water. Subsurface effluent was monitored to determine the contributing groundwater concentrations of numerous pollutants including chemical oxygen demand (COD), metals, and nitrates. Subsurface samples have an average reduction of COD concentrations of 20, 11, and 85% for the medium dairy Filter Strip 1 (FS1), medium dairy Filter Strip 2 (FS2), and the small Michigan dairy respectively, resulting in average subsurface concentrations of 355, 3960, and 718 mg L COD. Similar reductions were noted for ammonia and total Kjeldahl nitrogen (TKN) in the subsurface effluent. The small Michigan dairy was able to reduce the pollutant leachate concentrations of COD, TKN, and ammonia over a range of influent concentrations. Increased influent concentrations in the medium Michigan dairy filter strips resulted in an increase in COD, TKN, and ammonia concentrations in the leachate. Manganese was leached from the native soils at all filter strips as evidenced by the increase in manganese concentrations in the leachate. Nitrate concentrations were above standard drinking water limits (10 mg L), averaging subsurface concentrations of 11, 45, and 25 mg L NO-N for FS1, FS2, and the small Michigan dairy, respectively.     

Experimental study of cross-flow wet electrostatic precipitator

This paper reports development and testing of a novel cross-flow wet electrostatic precipitator (WESP), recently patented at Ohio University, that utilizes vertical columns of permeable material in the form of polypropylene ropes placed in a cross-flow configuration within a flue gas stream. The cross-flow design has large surface area, which provides scrubbing action; therefore, it has the potential for removing multiple pollutants, including particulates, gases, vapors, and mists. In this new method, the ropes are kept wet by the liquid (water) introduced from the top of the cells running downward on the ropes by capillary action, making the permeable materials act as the ground electrode for capturing particles from the flue gas. Preliminary testing has shown an efficiency of well above 80% using two cells and three sets of discharge electrodes. Since the material of construction is primarily corrosion-resistant polymeric material, both weight and cost reductions are expected from this new design.

Implications: The newly invented cross-flow WESP exhibit particulate collection efficiency of well above 80% when introduced in particulate-laden exhaust flow. This value was obtained using a two cells and three discharge electrodes configuration. The electric field strength has a substantial effect on the collection efficiency. Also, the pressure drop test results indicate that there is a potential to increase the collection area, which, in turn, will increase the collection efficiency further.     

Simulated Impacts of Climate Change on Current Farming Locations of Striped Catfish (Pangasianodon hypophthalmus; Sauvage) in the Mekong Delta,Vietnam

In Vietnam, culturing striped catfish makes an important contribution to the Mekong Delta’s economy. Water level rise during rainy season and salt intrusion during dry season affect the water exchange and quality for this culture. Sea level rise as a consequence of climate change will worsen these influences. In this study, water level rise and salt water intrusion for three sea level rise (SLR) scenarios (i.e., +30, +50, and +75 cm) were simulated. The results showed that at SLR +50, the 3-m-flood level would spread downstream and threaten farms located in AnGiang, DongThap and CanTho provinces. Rising salinity levels for SLR +75 would reduce the window appropriate for the culture in SocTrang and BenTre provinces, and in TienGiang’s coastal districts. Next to increasing dikes to reduce the impacts, the most tenable and least disruptive option to the farming community would be to shift to a salinity tolerant strain of catfish.     

Bioaccumulation of butyltins and liver damage in the demersal fish Cathorops spixii (Siluriformes,Ariidae)

The toxicity of butyltin compounds (BTs), mainly tributyltin (TBT), has been reported in different organisms. However, such an analysis in fish after field exposure with reference to the related biomarkers has not been commonly observed in the literature. This study presents the uptake of BTs in the liver of a neotropical marine catfish Cathorops spixii in Paranagua Bay, an important estuarine system located in southern Brazil. Two different areas, close to and distant from the harbor, were used for chemical analysis evaluation of hepatotoxicity through genetic, enzymatic, and histopathological biomarkers. The presence of polycyclic aromatic hydrocarbons in bile was also considered as a biomarker. The results showed a significant relationship between TBT levels and the inhibition of biotransformation enzymes and high occurrence of melanomacrophages in fish collected close to the harbor site. These effects were linked to the absence of TBT metabolites in the liver. In the second site, the presence of DBT was associated with an increase in EROD and GST activity. The larger amount of DNA damage as well as the highest oxidative stress was noted in fish from the less TBT-polluted area, where DBT and bile PAHs occurred. These findings showed different impact levels due to or increased by the chronic exposure of biota to BTs.     

Insights into real cotton-textile dyeing wastewater treatment using solar advanced oxidation processes

Different advanced oxidation processes (AOPs) were applied to the treatment of a real cotton-textile dyeing wastewater as a pre-oxidation step to enhance the biodegradability of the recalcitrant compounds, which can be further oxidized using a biological process. Tests were conducted on a lab-scale prototype using artificial solar radiation and at pilot scale with compound parabolic collectors using natural solar radiation. The cotton-textile dyeing wastewater presents a lilac color, with a maximum absorbance peak at 641 nm, alkaline pH (pH?=?8.2), moderate organic content (DOC?=?152 mg C L^?1, COD?=?684 mg O₂ L^?1) and low-moderate biodegradability (40 % after 28 days in Zahn–Wellens test). All the tested processes contributed to an effective decolorization and mineralization, but the most efficient process was the solar-photo-Fenton with an optimum catalyst concentration of 60 mg Fe²⁺ L^?1, leading to 98.5 % decolorization and 85.5 % mineralization after less than 0.1 and 5.8 kJ_UV L^?1, respectively. In order to achieve a final wastewater with a COD below 250 mg O₂ L^?1 (discharge limit into water bodies imposed by the Portuguese Legislation-Portaria no. 423/97 of 25 June 1997), considering the combination of a solar-photo-Fenton reaction with a biological process, the phototreatment energy required is 0.5 kJ_UV L^?1, consuming 7.5 mM hydrogen peroxide, resulting in 58.4 % of mineralization $ \left({t}_{30\mathrm{W}}=3.2\ \min; \overline{T}=30.7\ {}^{\circ}\mathrm{C};\overline{\mathrm{pH}}=2.80;{\overline{\mathrm{UV}}}_{G,n}={13\ \mathrm{W}\ \mathrm{m}}^{-2}\right). $      

Electrochemical removal of synthetic textile dyes from aqueous solutions using Ti/Pt anode: role of dye structure

In this work, the efficiency of electrochemical oxidation (EO) was investigated for removing a dye mixture containing Novacron Yellow (NY) and Remazol Red (RR) in aqueous solutions using platinum supported on titanium (Ti/Pt) as anode. Different current densities (20, 40 and 60 mA cm^?2) and temperatures (25, 40 and 60 °C) were studied during electrochemical treatment. After that, the EO of each of these dyes was separately investigated. The EO of each of these dyes was performed, varying only the current density and keeping the same temperature (25 °C). The elimination of colour was monitored by UV-visible spectroscopy, and the degradation of organic compounds was analysed by means of chemical oxygen demand (COD). Data obtained from the analysis of the dye mixture showed that the EO process was effective in colour removal, in which more than 90 % was removed. In the case of COD removal, the application of a current density greater than 40 mA cm^?2 favoured the oxygen evolution reaction, and no complete oxidation was achieved. Regarding the analysis of individual anodic oxidation dyes, it was appreciated that the data for the NY were very close to the results obtained for the oxidation of the dye mixture while the RR dye achieved higher colour removal but lower COD elimination. These results suggest that the oxidation efficiency is dependent on the nature of the organic molecule, and it was confirmed by the intermediates identified. Figure

Chemical structures of a NY and b RR     

Environmental monitoring model for a drainage basin obtained through spectral analysis of time series

The quality of results of an environmental monitoring plan is limited to the weakest component, which could be the analytical approach or sampling method. Considering both the possibilities and the fragility that sampling methods offer, this environmental monitoring study focused on the uncertainties caused by the time component. Four time series of nutrient concentration at two sampling points (PB1 and PB2) in the Ribeir?o Garcia basin in Blumenau, Brazil, which were significantly correlated to the spatial component, were considered with a 2-hour resolution to develop efficient sampling models. These models were based on the time at which there was the highest tendency toward adverse environmental effects. Fourier spectral analysis was used to evaluated the time series and resulted in two sampling models: (1) the SMCP (sampling model for critical period) that operated with 100% efficiency for registering the highest concentration of nutrients and was valid for 83% of the studied parameters; and (2) the SMGCP (sampling model for global critical period) that operated with 83 and 50% efficiency for PB1 and PB2, respectively.     

Optimization of artificial neural network models through genetic algorithms for surface ozone concentration forecasting

Introduction

This study proposes three methodologies to define artificial neural network models through genetic algorithms (GAs) to predict the next-day hourly average surface ozone (O₃) concentrations. GAs were applied to define the activation function in hidden layer and the number of hidden neurons.

Methods

Two of the methodologies define threshold models, which assume that the behaviour of the dependent variable (O₃ concentrations) changes when it enters in a different regime (two and four regimes were considered in this study). The change from one regime to another depends on a specific value (threshold value) of an explanatory variable (threshold variable), which is also defined by GAs. The predictor variables were the hourly average concentrations of carbon monoxide (CO), nitrogen oxide, nitrogen dioxide (NO₂), and O₃ (recorded in the previous day at an urban site with traffic influence) and also meteorological data (hourly averages of temperature, solar radiation, relative humidity and wind speed). The study was performed for the period from May to August 2004.

Results and discussion

Several models were achieved and only the best model of each methodology was analysed. In threshold models, the variables selected by GAs to define the O₃ regimes were temperature, CO and NO₂ concentrations, due to their importance in O₃ chemistry in an urban atmosphere.

Conclusion

In the prediction of O₃ concentrations, the threshold model that considers two regimes was the one that fitted the data most efficiently.     

Chromium (VI) remediation in aqueous solution by waste products (peel and seed) of mango (Mangifera indica L.) cultivars

The surface group characteristics of mango cultivar peels and seeds were evaluated by infrared spectra, PZC, and functional group composition. The adsorption/reduction of chromium (VI) in aqueous solutions was investigated by varying pH, contact time, initial Cr(VI) concentration, and adsorbent amount. The results show that both peel and seed powders of the mango cultivars showed significant adsorption/reduction capacity for Cr(VI) and that the desorption process obeys pseudo-second-order kinetics. Optimal adsorption occurred at pH 1.0, using a Cr(VI) concentration of 100 mg/L. On average, at pH 1.0, and a concentration of 3 g/L, the maximum adsorption/reduction capacity of Cr(VI) was 83% (peels 76%, seeds 90%). Of the mango powders tested, the most efficient were Tommy seed (100%) and Coite peel (98%) followed by Coite seed (96%) and Tommy peel powders (95%). The adsorption/reduction of Cr(VI) was complete (100%) by the mango seed, in comparison to the peel powders (97%) after 180 min. The data indicates that mango waste products, such as seed and peel powders, are both excellent candidates for the remediation of Cr(VI) from aqueous systems and due to the higher concentration of gallates and galloyl glucosides, the mango seed powders should be the powders of choice for future remediation projects.

     

Analytic Modeling of Rainwater Harvesting in the Brazilian Semiarid Northeast

During the past two decades, government efforts to provide water access to rural communities in Brazil's semiarid Northeast region have focused on building systems to capture and store rainwater, most importantly through the One Million Cisterns Program (P1MC). This article presents an analytic model based on daily precipitation data to evaluate the sustainability of rainwater capture. Application of this model to analysis of the P1MC reveals the heterogeneous climate in this region causes large spatial variability in the effectiveness of this program. In addition, the size of the area of capture, the run‐off coefficient of the roofs, and the amount of first‐flush diversion also have important effects. This analysis demonstrates while rainwater capture can offer sufficient water for drinking, as a stand‐alone solution it cannot meet P1MC objectives of guaranteeing sustainable and universal access to water for drinking, cooking, and basic hygiene in all regions and years.