• Energy Research

Irrigation accounts for 42% of the total freshwater withdrawals in the United States. Climate change, the pressure of a growing population, degrading water quality, and increased competition from other sectors could constrain continuous supply to meet future agricultural water demand. This study presents an evaluation framework to assess the potential reuse of agricultural drainage water for crop irrigation. Using a regional approach, we review the current state of agricultural drainage treatment and reuse and the institutional, economic, and other barriers that can influence the reuse decision. In the 31 eastern states, agricultural drainage contains valuable nutrients that can be reused for irrigation with minimal treatment, while the 17 western states struggle with large volumes of saline drainage that can contain constituents of concern (e.g., selenium), preventing reuse without treatment. Using a new decision-support tool called WaterTAP3, a potential treatment train for saline agricultural drainage was analyzed to identify treatment challenges, research needs, and the potential implementation at a larger scale. As demonstrated by our case study, desalination of agricultural drainage is costly and energy intensive and will require sizable investments to fully develop and optimize technologies as well as manage the generated waste and brine.

Irrigation accounts for 42% of the total freshwater withdrawals in the United States. Climate change, the pressure of a growing population, degrading water quality, and increased competition from other sectors could constrain continuous supply to meet future agricultural water demand. This study presents an evaluation framework to assess the potential reuse of agricultural drainage water for crop irrigation. Using a regional approach, we review the current state of agricultural drainage treatment and reuse and the institutional, economic, and other barriers that can influence the reuse decision. In the 31 eastern states, agricultural drainage contains valuable nutrients that can be reused for irrigation with minimal treatment, while the 17 western states struggle with large volumes of saline drainage that can contain constituents of concern (e.g., selenium), preventing reuse without treatment. Using a new decision-support tool called WaterTAP3, a potential treatment train for saline agricultural drainage was analyzed to identify treatment challenges, research needs, and the potential implementation at a larger scale. As demonstrated by our case study, desalination of agricultural drainage is costly and energy intensive and will require sizable investments to fully develop and optimize technologies as well as manage the generated waste and brine.

Sludge or waste activated sludge (WAS) generated from wastewater treatment plants may be considered a nuisance. It is a key source for secondary environmental contamination on account of the presence of diverse pollutants (polycyclic aromatic hydrocarbons, dioxins, furans, heavy metals, etc.). Innovative and cost-effective sludge treatment pathways are a prerequisite for the safe and environment-friendly disposal of WAS. This article delivers an assessment of the leading disposal (volume reduction) and energy recovery routes such as anaerobic digestion, incineration, pyrolysis, gasification and enhanced digestion using microbial fuel cell along with their comparative evaluation, to measure their suitability for different sludge compositions and resources availability. Furthermore, the authors shed light on the bio-refinery and resource recovery approaches to extract value added products and nutrients from WAS, and control options for metal elements and micro-pollutants in sewage sludge. Recovery of enzymes, bio-plastics, bio-pesticides, proteins and phosphorus are discussed as a means to visualize sludge as a potential opportunity instead of a nuisance.

Sludge or waste activated sludge (WAS) generated from wastewater treatment plants may be considered a nuisance. It is a key source for secondary environmental contamination on account of the presence of diverse pollutants (polycyclic aromatic hydrocarbons, dioxins, furans, heavy metals, etc.). Innovative and cost-effective sludge treatment pathways are a prerequisite for the safe and environment-friendly disposal of WAS. This article delivers an assessment of the leading disposal (volume reduction) and energy recovery routes such as anaerobic digestion, incineration, pyrolysis, gasification and enhanced digestion using microbial fuel cell along with their comparative evaluation, to measure their suitability for different sludge compositions and resources availability. Furthermore, the authors shed light on the bio-refinery and resource recovery approaches to extract value added products and nutrients from WAS, and control options for metal elements and micro-pollutants in sewage sludge. Recovery of enzymes, bio-plastics, bio-pesticides, proteins and phosphorus are discussed as a means to visualize sludge as a potential opportunity instead of a nuisance.

Adsorption is an efficient and low-cost technology used to purify volatile organic compounds (VOCs). In the current study, novel microbial adsorbents were synthesized using cells of lyophilized fungi (Ophiostoma stenoceras LLC) or bacteria (Pseudomonas veronii ZW) that were modified by aminomethylation. Based on the adsorption performance and structural characterization results, the modified fungal biosorbent was the best. Its maximum adsorption capacities for ethyl acetate, α-pinene, and n-hexane were 620, 454, and 374 mg·g-1, respectively, which were much higher than those of other synthesized biosorbents. The specific surface area of the fungal biosorbent was 20 m2·g-1, and most of the components were hydrocarbon compounds and polysaccharides. The VOC adsorption process on these synthesized biosorbents was in accordance with the Langmuir isothermal model and the pseudo-first-order kinetic model, thereby suggesting that physical adsorption was the dominant mechanism. The fungal biosorbent could be used for five consecutive VOC sorption-desorption cycles without any obvious decrease in adsorption capacity.

Adsorption is an efficient and low-cost technology used to purify volatile organic compounds (VOCs). In the current study, novel microbial adsorbents were synthesized using cells of lyophilized fungi (Ophiostoma stenoceras LLC) or bacteria (Pseudomonas veronii ZW) that were modified by aminomethylation. Based on the adsorption performance and structural characterization results, the modified fungal biosorbent was the best. Its maximum adsorption capacities for ethyl acetate, α-pinene, and n-hexane were 620, 454, and 374 mg·g-1, respectively, which were much higher than those of other synthesized biosorbents. The specific surface area of the fungal biosorbent was 20 m2·g-1, and most of the components were hydrocarbon compounds and polysaccharides. The VOC adsorption process on these synthesized biosorbents was in accordance with the Langmuir isothermal model and the pseudo-first-order kinetic model, thereby suggesting that physical adsorption was the dominant mechanism. The fungal biosorbent could be used for five consecutive VOC sorption-desorption cycles without any obvious decrease in adsorption capacity.

One of the most important features of photocatalytic materials intended to be used for water treatment is their long-term stability. The study is focused on the application of thermal and chemical treatments for the reactivation of TiO2-SnS2 composite photocatalyst, prepared by hydrothermal synthesis and immobilized on the glass support using titania/silica binder. Such a catalytic system was applied in solar-driven treatment, solar/TiO2-SnS2/H2O2, for the purification of water contaminated with diclofenac (DCF). The effectiveness of studied reactivation methods for retaining TiO2-SnS2 activity in consecutive cycles was evaluated on basis of DCF removal and conversion, and TOC removal and mineralization of organic content. Besides these water quality parameters, biodegradability changes in DCF aqueous solution treated by solar/TiO2-SnS2/H2O2 process using simply reused (air-dried) and thermally and chemically reactivated composite photocatalyst through six consecutive cycles were monitored. It was established that both thermal and chemical reactivation retain TiO2-SnS2 activity in the second cycle of its reuse. However, both treatments caused the alteration in the TiO2-SnS2 morphology due to the partial transformation of visible-active SnS2 into non-active SnO2. Such alteration, repeated through consecutive reactivation and reuse, was reflected through gradual activity loss of TiO2-SnS2 composite in applied solar-driven water treatment.

One of the most important features of photocatalytic materials intended to be used for water treatment is their long-term stability. The study is focused on the application of thermal and chemical treatments for the reactivation of TiO2-SnS2 composite photocatalyst, prepared by hydrothermal synthesis and immobilized on the glass support using titania/silica binder. Such a catalytic system was applied in solar-driven treatment, solar/TiO2-SnS2/H2O2, for the purification of water contaminated with diclofenac (DCF). The effectiveness of studied reactivation methods for retaining TiO2-SnS2 activity in consecutive cycles was evaluated on basis of DCF removal and conversion, and TOC removal and mineralization of organic content. Besides these water quality parameters, biodegradability changes in DCF aqueous solution treated by solar/TiO2-SnS2/H2O2 process using simply reused (air-dried) and thermally and chemically reactivated composite photocatalyst through six consecutive cycles were monitored. It was established that both thermal and chemical reactivation retain TiO2-SnS2 activity in the second cycle of its reuse. However, both treatments caused the alteration in the TiO2-SnS2 morphology due to the partial transformation of visible-active SnS2 into non-active SnO2. Such alteration, repeated through consecutive reactivation and reuse, was reflected through gradual activity loss of TiO2-SnS2 composite in applied solar-driven water treatment.