Carlos A. Madera-Parra

Phytoremediation of Landfill Leachate with Colocasia esculenta, Gynerum sagittatum and Heliconia psittacorum in Constructed Wetlands

This study assessed the accumulation of Cd (II), Hg (II), Cr (VI) and Pb (II) in Gynerium sagittatum (Gs), Colocasia esculenta (Ce) and Heliconia psittacorum (He) planted in constructed wetlands treating synthetic landfill leachate. Sixteen bioreactors were operated in two experimental blocks. Metal concentrations in the influent and effluent; root, stem, branch and leaves of plants were analysed, as well as COD, N-NH4+, TKN, T, pH, ORP, DO, and EC. Average removal efficiencies of COD, TKN and NH4+-N were 66, 67 and 72%, respectively and heavy metal removal ranged from 92 to 98% in all units. Cr (VI) was not detected in any effluent sample. The bioconcentration factors (BCF) were 100 -102. The BCF of Cr (VI) was the lowest: 0.59 and 2.5 (L kg−1) for Gs and He respectively; whilst Cd (II) had the highest (130–135 L kg−1) for Gs. Roots showed a higher metal content than shoots. Translocation factors (TF) were lower, He was the plant exhibiting TFs >1 for Pb (II), Cr (T) and Hg (II) and 0.4–0.9 for Cd (II) and Cr (VI). The evaluated plants demonstrate their suitability for phytoremediation of landfill leachate and all of them can be categorized as metals accumulators.

Performance of a system with full- and pilot-scale sludge drying reed bed units treating septic tank sludge in Brazil.

This study investigated the performance of sludge drying reed beds (SDRB) at full- and pilot-scale treating sludge from septic tanks in the city of Belo Horizonte, Brazil. The treatment units, planted with Cynodon spp., were based on an adaptation of the first-stage of the French vertical-flow constructed wetland, originally developed for treating sewage. Two different operational phases were investigated; in the first one, the full-scale unit was used together with six pilot-scale columns in order to test different feeding strategies. For the second phase, only the full-scale unit was used, including a recirculation of the filtered effluent (percolate) to one of the units of the French vertical wetland. Sludge application was done once a week emptying a full truck, during 25 weeks. The sludge was predominantly diluted, leading to low solids loading rates (median values of 18 kgTS m(-2) year(-1)). Chemical oxygen demand removal efficiency in the full-scale unit was reasonable (median of 71%), but the total solids removal was only moderate (median of 44%) in the full-scale unit without recirculation. Recirculation did not bring substantial improvements in the overall performance. The other loading conditions implemented in the pilot columns also did not show statistically different performances.

Phytoremediation Using Terrestrial Plants

Phytoremediation is broadly referred to as a biotechnology that uses vegetation to contain, sequester, remove, or degrade inorganic and organic contaminants in soil, sediment, surface water, and groundwater. Its application has been recommended as cheaper and more effective alternatives for the removal and recovery of pollutants. Despite being a relatively new technology, it has great potential as a green alternative for the management of pollutants, especially in tropical areas where the rich diversity of plants means greater potential for handling different contaminants. However, its use is often limited by the unavailability of appropriate plant species. Thus, there has been recognized a list of criteria that should take into account in the process to select a plant for inclusion in phytotechnology treatment systems. Plants through different biophysical and biochemical processes, such as adsorption, transport and translocation, hyperaccumulation or transformation, and mineralization, can remediate pollutants. Constructed wetland systems (CWS) are one of the most common applications using phytoremediation. In those systems, the interactions of plants and microorganisms act for pollutant removal. Plants for phytoremediation in constructed wetlands offer, therefore, a suitable alternative for pollution cleanup, considering its wide diversity and specific characteristic of adaptation to adequate or harsh conditions throughout its life cycle. This includes acclimation to receive high or low levels of solar radiation, longer photoperiods along entire year (12 h), overcoming extended drought, high precipitation, and/or distinct wet and dry seasons. The chapter “Phytoremediation Using Terrestrial Plants” includes the main features regarding tropical native plants and its uses for this type of technology, emphasizing on constructed wetland systems as a main application of phytoremediation.

The multigenerational effects of water contamination and endocrine disrupting chemicals on the fitness of Drosophila melanogaster

Abstract Water pollution due to human activities produces sedimentation, excessive nutrients, and toxic chemicals, and this, in turn, has an effect on the normal endocrine functioning of living beings. Overall, water pollution may affect some components of the fitness of organisms (e.g., developmental time and fertility). Some toxic compounds found in polluted waters are known as endocrine disruptors (ED), and among these are nonhalogenated phenolic chemicals such as bisphenol A and nonylphenol. To evaluate the effect of nonhalogenated phenolic chemicals on the endocrine system, we subjected two generations (F0 and F1) of Drosophila melanogaster to different concentrations of ED. Specifically, treatments involved wastewater, which had the highest level of ED (bisphenol A and nonylphenol) and treated wastewater from a constructed Heliconia psittacorum wetland with horizontal subsurface water flow (He); the treated wastewater was the treatment with the lowest level of ED. We evaluated the development time from egg to pupa and from pupa to adult as well as fertility. The results show that for individuals exposed to treated wastewater, the developmental time from egg to pupae was shorter in individuals of the F1 generation than in the F0 generation. Additionally, the time from pupae to adult was longer for flies growing in the H. psittacorum treated wastewater. Furthermore, fertility was lower in the F1 generation than in the F0 generation. Although different concentrations of bisphenol A and nonylphenol had no significant effect on the components of fitness of D. melanogaster (developmental time and fertility), there was a trend across generations, likely as a result of selection imposed on the flies. It is possible that the flies developed different strategies to avoid the effects of the various environmental stressors.

Study of the occurrence and ecosystem danger of selected endocrine disruptors in the urban water cycle of the city of Bogotá, Colombia

ABSTRACT Endocrine disruptors have been studied for their high occurrence in different environments including aquatic; however, in the context of developing countries, their occurrence, magnitude and potential threat have little information. This study involved the analysis of various components of the urban water cycle in the city of Bogotá, Colombia. As a result, it was found that the compounds with the highest occurrence are plasticizers such as phthalates and bisphenol A, whereas among the drugs, carbamazepine presented the highest concentrations (0.68–31.45 µg L−1); the analysis of the threat coefficient (HQ) showed the importance of bis(2-ethylhexyl) phthalate (BEHP) and estrone (E1) that can reach surface waters from domestic and industrial discharges.

Constructed Wetlands for Landfill Leachate Treatment

Sanitary landfills are the most widely used method of solid waste disposal around the world. Landfill leachate (LL) is recognized as one of the most critical issues for landfill operators. Landfill leachate may contain large amounts of organic matter (biodegradable, and refractory to biodegradation), as well as ammonia-nitrogen, heavy metals (HM) and chlorinated organic and inorganic salts. Various landfill leachate treatment technologies have been broadly used, including biological processes (aerobic, anaerobic and anoxic) and physicochemical processes (oxidation, precipitation, coagulation/flocculation, ozonation, activated carbon adsorption, electrochemical oxidation, Fenton process, membrane filtration). Constructed wetlands are classified among the biological methods that use phytoremediation for polluted liquid treatment. They are defined as engineered systems that use natural processes (vegetation, soils and microorganisms) to remove, transform and degrade pollutants from wastewater, creating an efficient synergic effect. The effectiveness of constructed wetlands for landfill leachate treatment has been extensively demonstrated and its full-scale implementation is rising among regions given its adaptability and capacity to efficiently treat landfill leachate.

Organic matter removal during pilot-scale soil aquifer treatment for domestic wastewater in the tropics.

The potential of enhancing water uses using soil aquifer treatment (SAT) is an interesting alternative for tropical regions, limited only by lack of knowledge on its performance in local conditions and the feasibility of adapting this technology. A SAT pilot study was conducted to analyze the phenomena associated with the transformation of organic matter (OM) from domestic wastewater. Chemically enhanced primary effluent collected at the Cañaveralejo wastewater treatment plant (Cali, Colombia) was used to feed pilot-scale SAT units at a rate of 1.25 m.d⁻¹. Dissolved organic carbon (DOC) removal in a 5.0 m length and 0.1 m diameter column packed with sand was 64.4%, while a similar column packed with a Mollisol soil from Valle del Cauca region yielded 56.2%. Oxygen availability was an important factor in OM degradation, given that the sand column degraded OM aerobically and the soil column degraded OM under oxic as well as anoxic conditions. SAT acted as a reliable barrier for DOC in tropical conditions. Nevertheless, operational problems such as clogging indicated that probably Mollisol soil may not be the suitable for SAT or that this particular effluent requires further pre-treatment before SAT.