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1.
Nanomaterials (Basel) ; 14(13)2024 Jun 25.
Article in English | MEDLINE | ID: mdl-38998692

ABSTRACT

Water pollution, particularly from organic contaminants like dyes, is a pressing issue, prompting exploration into advanced oxidation processes (AOPs) as potential solutions. This study focuses on synthesizing Cu2O on cellulose-based fabric using Eucalyptus globulus leaf extracts. The resulting catalysts effectively degraded methylene blue through photocatalysis under LED visible light and heterogeneous Fenton-like reactions with H2O2, demonstrating reusability. Mechanistic insights were gained through analyses of the extracts before and after Cu2O synthesis, revealing the role of phenolic compounds and reducing sugars in nanoparticle formation. Cu2O nanoparticles on cellulose-based fabric were characterized in terms of their morphology, structure, and bandgap via SEM-EDS, XRD, Raman, FTIR, UV-Vis DRS, and TGA. The degradation of methylene blue was pH-dependent; photocatalysis was more efficient at neutral pH due to hydroxyl and superoxide radical production, while Fenton-like reactions showed greater efficiency at acidic pH, primarily generating hydroxyl radicals. Cu2O used in Fenton-like reactions exhibited lower reusability compared to photocatalysis, suggesting deterioration. This research not only advances understanding of catalytic processes but also holds promise for sustainable water treatment solutions, contributing to environmental protection and resource conservation.

2.
Plants (Basel) ; 13(2)2024 Jan 06.
Article in English | MEDLINE | ID: mdl-38256712

ABSTRACT

Drought is a major challenge for agriculture worldwide, being one of the main causes of losses in plant production. Various studies reported that some soil's bacteria can improve plant tolerance to environmental stresses by the enhancement of water and nutrient uptake by plants. The Atacama Desert in Chile, the driest place on earth, harbors a largely unexplored microbial richness. This study aimed to evaluate the ability of various Bacillus sp. from the hyper arid Atacama Desert in the improvement in tolerance to drought stress in lettuce (Lactuca sativa L. var. capitata, cv. "Super Milanesa") plants. Seven strains of Bacillus spp. were isolated from the rhizosphere of the Chilean endemic plants Metharme lanata and Nolana jaffuelii, and then identified using the 16s rRNA gene. Indole acetic acid (IAA) production, phosphate solubilization, nitrogen fixation, and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity were assessed. Lettuce plants were inoculated with Bacillus spp. strains and subjected to two different irrigation conditions (95% and 45% of field capacity) and their biomass, net photosynthesis, relative water content, photosynthetic pigments, nitrogen and phosphorus uptake, oxidative damage, proline production, and phenolic compounds were evaluated. The results indicated that plants inoculated with B. atrophaeus, B. ginsengihumi, and B. tequilensis demonstrated the highest growth under drought conditions compared to non-inoculated plants. Treatments increased biomass production and were strongly associated with enhanced N-uptake, water status, chlorophyll content, and photosynthetic activity. Our results show that specific Bacillus species from the Atacama Desert enhance drought stress tolerance in lettuce plants by promoting several beneficial plant traits that facilitate water absorption and nutrient uptake, which support the use of this unexplored and unexploited natural resource as potent bioinoculants to improve plant production under increasing drought conditions.

3.
J Environ Manage ; 351: 119812, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38100865

ABSTRACT

Phosphorus (P) is an essential element for life that must be managed sustainably. The institutional framework for P recovery from wastewater includes policies, regulations, plans, and actions that promote the recovery, recycling, and safe use of this element, aimed at moving toward more sustainable nutrient management and environmental protection. This review analyzes the status of the institutional framework for P recovery from wastewater in different countries around the world. Europe is the continent where the most progress has been made in terms of legislation. Countries such as Germany, the Netherlands, Austria, and Denmark have already implemented policies and regulations that promote environmental protection, as well as P recovery and reuse. In other parts of the world, such as the United States, China, and Japan, there have also been significant advances in promoting the closure of the P cycle, with the implementation of advanced recovery technologies in wastewater treatment plants and regional/national action plans. By contrast, in Latin America there has been little progress in P treatment and recovery, with a weak regulatory framework, unclear goals, and insufficient allocation of techno-economic resources. In this context, it is necessary to reinforce the comprehensive institutional framework, which covers technological aspects, economic incentives, political agreements, and regulations, to promote the sustainable management of this valuable resource.


Subject(s)
Phosphorus , Wastewater , Conservation of Natural Resources , Policy , Recycling , Waste Disposal, Fluid
4.
Plants (Basel) ; 12(10)2023 May 18.
Article in English | MEDLINE | ID: mdl-37653935

ABSTRACT

Irrigated agriculture is responsible for a third of global agricultural production, but the overuse of water resources and intensification of farming practices threaten its sustainability. The use of saline water in irrigation has become an alternative in areas subjected to frequent drought, but this practice affects plant growth due to osmotic impact and excess of ions. Plant-growth-promoting rhizobacteria (PGPR) can mitigate the negative impacts of salinity and other abiotic factors on crop yields. Actinobacteria from the hyper-arid Atacama Desert could increase the plant tolerance to salinity, allowing their use as biofertilizers for lettuce crops using waters with high salt contents. In this work, rhizosphere samples of halophytic Metharme lanata were obtained from Atacama Desert, and actinobacteria were isolated and identified by 16S gene sequencing. The PGPR activities of phosphate solubilization, nitrogen fixation, and the production of siderophore and auxin were assessed at increasing concentrations of NaCl, as well as the enhancement of salt tolerance in lettuce plants irrigated with 100 mM of NaCl. Photosynthesis activity and chlorophyll content, proline content, lipid peroxidation, cation and P concentration, and the identification and quantification of phenolic compounds were assessed. The strains S. niveoruber ATMLC132021 and S. lienomycini ATMLC122021 were positive for nitrogen fixation and P solubilization activities and produced auxin up to 200 mM NaCl. In lettuce plants, both strains were able to improve salt stress tolerance by increasing proline contents, carotenoids, chlorophyll, water use efficiency (WUE), stomatal conductance (gs), and net photosynthesis (A), concomitantly with the overproduction of the phenolic compound dicaffeoylquinic acid. All these traits were positively correlated with the biomass production under saltwater irrigation, suggesting its possible use as bioinoculants for the agriculture in areas where the water resources are scarce and usually with high salt concentrations.

5.
Methods Mol Biol ; 2704: 43-50, 2023.
Article in English | MEDLINE | ID: mdl-37642837

ABSTRACT

The phytosterol-biotransforming strains can be selected from Mycobacterium sp. using a high concentration of ß-sitosterol. The selection is made by culturing the strains in a medium enriched with 14 g/L of ß-sitosterol as the unique source of carbon. During 2 months, the bacterial cultures are transferred successively. The extraction of the biotransformation products is made with methanol and ethyl acetate. The qualitative and quantitative analyses are made by means of thin-layer chromatography, gas-liquid chromatography (GLC), and GLC-mass spectrometry. Under these conditions, it is observed that after seven transfers, the strains Mycobacterium sp. MB-3683 and Mycobacterium fortuitum B-11045 increase their biotransformation capacity from 20% to 64% and from 34% to 55%, respectively. The products in the highest proportion identified for each trial are androstenedione and androstadienedione. The results suggest that the high substrate concentration could be a selective mechanism to obtain strains more efficient in the biotransformation of ß-sitosterol into steroidal bases.


Subject(s)
Phytosterols , Gas Chromatography-Mass Spectrometry , Androstenedione , Carbon , Chromatography, Thin Layer
6.
Methods Mol Biol ; 2704: 329-336, 2023.
Article in English | MEDLINE | ID: mdl-37642854

ABSTRACT

Stigmasterol is a phytosterol contained in kraft mill effluent that is able to increase over 100% after aerobic biological treatment. This compound can act as an endocrine disrupter as its structure is similar to that of cholesterol. Furthermore, stigmasterol contained in kraft mill effluent shows high toxicity (25-fold more than ß-sitosterol) to aquatic organisms such as Daphnia magna. However, the operation of the aerobic treatment and biomass adaptation could be affecting their removal. The performances of activated sludge (AS), aerated lagoon (AL), and moving bed biofilm reactors (MBBR) are compared to remove the stigmasterol contained in kraft mill effluent. The AL operates at a hydraulic retention time of 6 h and removes up to 90% of phytosterols. So, a 96% of stigmasterol is removed by AL when the sterol retention load is 0.6 mg/L · d. However, stigmasterol concentrations increase from 29% to 37% at a low stigmasterol load rate (0.2 mg/L · d). On the other hand, the stigmasterol is removed between 65% and 87% by an AS under a hydraulic retention time of 3 h. Moreover, a 100% of stigmasterol can be removed by the MBBR when the hydraulic retention time is 2 days.


Subject(s)
Phytosterols , Stigmasterol , Biofilms , Bioreactors , Acclimatization , Sewage
7.
Article in English | MEDLINE | ID: mdl-36767672

ABSTRACT

Laundry greywater is considered as an alternative source of non-potable water, as it is discharged in approximately 70% of homes. Because this water contains compounds such as biodegradable and recalcitrant organic matter, surfactants, and microbiological compounds, it must be treated prior to reuse. Therefore, the objective of this study was to assess the behavior of organic matter and antibiotic-resistant bacteria (ARB) in greywater treated by a constructed wetland (CW). The results show that the organic matter removal efficiencies were 67.19%, 50.15%, and 63.57% for biological oxygen demand (BOD5), chemical oxygen demand (COD) and total organic carbon (TOC), respectively; these efficiencies were not significant (p > 0.05). In addition, the CW allows the distribution of TOC and ionic compounds in the fractions below 1000 Da to increase by 5.03% and 13.05%, respectively. Meanwhile, the treatment of microbiological compounds generated non-significant removals (p > 0.05), along with increases in bacteria resistant to the antibiotics ciprofloxacin (CIP) and ceftriaxone (CTX) of 36.34%, and 40.79%, respectively. In addition, a strong association between ARB to CIP, CTX, cationic and non-ionic surfactants was determined, indicating the role of surfactants in ARB selection. It is suggested that disinfection systems should be employed prior to the reuse of the treated water.


Subject(s)
Water Pollutants, Chemical , Wetlands , Wastewater , Angiotensin Receptor Antagonists , Water Pollutants, Chemical/analysis , Angiotensin-Converting Enzyme Inhibitors , Organic Chemicals , Water , Ceftriaxone , Bacteria , Anti-Bacterial Agents/pharmacology , Waste Disposal, Fluid/methods
9.
J Environ Manage ; 324: 116320, 2022 Dec 15.
Article in English | MEDLINE | ID: mdl-36183529

ABSTRACT

Cryptosporidium sp. and Giardia sp. are parasites that cause diseases in the population. Most of parasite diseases regarding the consumption of drinking water polluted with sewage are caused by Cryptosporidium sp. or Giardia sp. it is because of the incomplete disinfection of the wastewater treatment. Therefore, in this work the removal or inactivation efficiency of different treatment technologies presented by around 40 scientific studies was evaluated, with a view to water circularity. For Cryptosporidium sp., we conclude that the most efficient secondary technologies are aerobic technologies, which remove between 0.00 and 2.17 log units (Ulog), with activated sludge presenting the greatest efficiency, and that the tertiary technologies with the greatest removal are those that use ultrasound, which reach removal values of 3.17 Ulog. In the case of Giardia sp., the secondary technologies with the greatest removal are anaerobic technologies, with values between 0.00 and 3.80 Ulog, and the tertiary technologies with the greatest removal are those that combine filtration with UV or a chemical disinfection agent. Despite the removal values obtained, the greatest concern remains detecting and quantifying the infectious forms of both parasites in effluents; therefore, although the technologies perform adequately, discharge effluents must be monitored with more sensitive techniques, above all aiming for circularity of the treated water in a context of the water scarcity that affects some parts of the world.


Subject(s)
Cryptosporidiosis , Cryptosporidium , Giardiasis , Water Purification , Animals , Giardia , Sewage/parasitology , Water , Oocysts , Giardiasis/epidemiology , Water Purification/methods
10.
J Environ Manage ; 324: 116357, 2022 Dec 15.
Article in English | MEDLINE | ID: mdl-36202036

ABSTRACT

Reducing the costs and environmental impacts of sludge management is currently one of the main challenges faced by the wastewater treatment sector. Anaerobic digestion followed by land application has been widely endorsed as a low-impact approach to sludge management, mainly due to the recovery of biogas and the valorization of digestate. However, the influence that the operational conditions of digestion and the management practices of land application can have over the environmental performance of this strategy has been scarcely studied. Furthermore, most of the previous studies dealing with the environmental assessment of this strategy use simplified methods for estimating emissions after land application of sludge, and the lack of systematic accounting of these environmental flows might significantly affect the validity and comparability of the results. Therefore, this work performed an assessment of the influence that 4 relevant practices can have over the environmental impacts of this approach in the context of south-central Chile, providing a mass-balanced inventory for nitrogen, phosphorus and heavy metals in soil based on the ad hoc implementation of models developed for agricultural Life Cycle Assessment (LCA). A total of 16 scenarios were defined and 10 impact categories were evaluated, with the results showing that the environmental impacts were greatly influenced by the variables under study. Overall, solids retention time and the inclusion of pre-treatment mainly influenced climate change, fossil resource depletion and terrestrial ecotoxicity potential, while sludge application rate influenced the eutrophication, water ecotoxicity and human toxicity categories. The type of crop in the receiving soil was a significant driver behind the differences observed in the human toxicity category, which showed the highest variation and relevance in the final weighted result. The results clearly highlight the relevance of using context specific data as well as of quantifying the fate of nutrients, metals and heavy metals during LCA of sludge management. Based on the results, some policy and decision-making recommendations are formulated to optimize the environmental performance of sludge digestion and land application.


Subject(s)
Metals, Heavy , Sewage , Humans , Chile , Eutrophication , Soil
11.
Environ Technol ; : 1-15, 2022 Sep 13.
Article in English | MEDLINE | ID: mdl-36101485

ABSTRACT

The aim of this work was to assess effect of saturated constructed wetland-Microbial fuel cell system on dissolved oxygen gradient, electricity generation and ammonium removal. Two laboratory-scale systems, one planted with Schoenoplectus californicus (SCW1-MFC) and other without plant (SCW2-MFC), were fed discontinuously with synthetic wastewater over 90 days. Both systems were operated at different organic loading rate (12 and 28 g COD/m2d) and ammonium loading rate (1.6 and 3.0 g NH4+- N/m2 d) under open circuit and close circuit mode. The results indicate that between lower and upper zones of wetlands the average values were in the range of 1.22 ± 0.32 to 1.39 ± 0.27 mg O2/L in SCW1-MFC and 1.28 ± 0.24 to 1.56 ± 0.31 mg O2/L in SCW2-MFC. The effect of operating mode (closed and open circuit) and vegetation on DO was not significant (p > 0.05). Chemical oxygen demand (COD) removal efficiencies, fluctuated between 90 and 95% in the SCW1-MFC and 82 and 94% in the SCW2-MFC system. Regarding NH4+- N, removal efficiencies were above 85% in both systems reaching values maximus 98%. The maximum power density generated was 4 and 10 mW/m2 in SCW1-MFC, while SCW2-MFC recorded the highest values (12 and 22 mW/m2).

12.
Int J Phytoremediation ; 24(6): 610-621, 2022.
Article in English | MEDLINE | ID: mdl-34382468

ABSTRACT

The aim of this study was to evaluate long-term phosphorus (P) retention in a pilot-scale system made of four horizontal subsurface flow (HSSF) constructed wetlands for wastewater treatment. Each wetland had an area of 4.5 m2 and was operated for nearly 8 years (2833 days). Two wetlands with Schoenoplectus californicus (HSSF-Sch) and the other two with Phragmites australis (HSSF-Phr) were planted. The P removal efficiency was 18% for both types of HSSF wetlands. The primary factors that correlated with long-term P retention efficiency in HSSF were phosphorus loading rate (PLR), hydraulic loading rate (HLR) and dissolved oxygen (DO). Average biomass production of HSSF-Phr and HSSF-Sch was 4.8 and 12.1 kg dry weight (DW)/m2, respectively. The P uptake by the plant increased over the years of operation from 1.8 gP/m2 to 7.1 gP/m2 for Phragmites and from 3.2 to 7.4 gP/m2 for Schoenoplectus over the same periods. Moreover, the warm season (S/Sm) was more efficient reaching 14% P uptake than the cold season (F/W) with 9%. These results suggest that both plants' P retention capacity in HSSF systems represents a sustainable treatment in the long term.Novelty statement Long-term (8 years) phosphorus uptake by Schoenoplectus californicus and Phragmites australis and retention in pilot-scale constructed wetlands are evaluated. Schoenoplectus californicus is an uncommon species that has been less studied for phosphorus uptake compared to Phragmites australis, a globally known species in constructed wetlands. Moreover, some studies evaluating the performance of constructed wetland systems for domestic wastewater treatment are usually limited in time (1-3 years). Therefore, this long-term study demonstrates that the plant plays an important role in phosphorus retention, especially the species Schoenoplectus californicus. So, the phosphorus uptake by plants can contribute between 9 and 14% of the phosphorus load of constructed wetland systems in early years of operation.


Subject(s)
Water Purification , Wetlands , Biodegradation, Environmental , Phosphorus , Plants , Poaceae , Waste Disposal, Fluid/methods , Water Purification/methods
13.
Sci Total Environ ; 753: 142075, 2021 Jan 20.
Article in English | MEDLINE | ID: mdl-33207444

ABSTRACT

Microbial fuel cells integrated into constructed wetlands have been previously studied. Nevertheless, their application as a suitable treatment for wastewater is still in the developmental stage. In this context, the aim of this study was to evaluate organic matter removal and nitrogen transformation by a microbial fuel cell integrated into a constructed wetland (CWMFC). To accomplish this, three experimental systems were operated under batch-mode conditions over 170 days: i) one was planted with Schoenoplectus californicus (P-CWMFC); ii) another was unplanted (NP-CWMFC); and iii) the third system did not have any electrodes (CW) and was used as a control. Chemical oxygen demand (COD) removal efficiency ranged between 74-87%, 69-81% and 62-72% for the P-CWMFC, NP-CWMFC and CW systems, respectively, with organic loading rates (OLR) ranging from 4.8 to 7.9 g COD/m2 d. NH4+-N removal efficiency exceeded 98%, 90% and 83% for P-CWMFC, NP-CWMFC and CW, respectively. Wastewater treatment performance was improved due to anaerobic oxidation that occurred on the anodes. Organic matter removal was 18% higher in closed-circuit mode than in open-circuit mode in both integrated systems (P-CWMFC and NP-CWMFC), and these differences were significant (p < 0.05). With respect to the performance of microbial fuel cells, the maximum power density (8.6 mW/m2) was achieved at an organic loading rate of 7.9 g COD/m2 d with an internal resistance and coulombic efficiency of 251â€¯Ω and 2.4%, respectively. The results obtained in this work can provide positive impacts on CW development by enhancing anaerobic degradation without forced aeration.


Subject(s)
Bioelectric Energy Sources , Biological Oxygen Demand Analysis , Nitrogen , Wastewater , Wetlands
14.
Plant Physiol Biochem ; 158: 396-409, 2021 Jan.
Article in English | MEDLINE | ID: mdl-33248899

ABSTRACT

The aim was to identify the effects of AM symbiosis on the expression patterns of genes associated with K+ and Na+ compartmentalization and translocation and on K+/Na+ homeostasis in some lettuce (Lactuca sativa) cultivars as well as the effects of the relative abundance of plant AQPs on plant water status. Two AM fungi species (Funneliformis mosseae and Claroideoglomus lamellosum) isolated from the hyper-arid Atacama Desert (northern Chile) were inoculated to two lettuce cultivars (Grand Rapids and Lollo Bionda), and watered with 0 and 60 mM NaCl. At 60 days of plant growth, the AM symbiotic development, biomass production, nutrient content (Pi, Na+, K+), physiological parameters, gene expressions of ion channels and transporters (NHX and HKT1), and aquaporins proteins abundance (phosphorylated and non-phosphorylated) were evaluated. Salinity increased the AM root colonization by both inocula. AM lettuce plants showed an improved growth, increased relative water content and improved of K/Na ratio in root. In Grand Rapids cultivar, the high efficiency of photosystem II was higher than Lollo Bionda cultivar; on the contrary, stomatal conductance was higher in Lollo Bionda. Nevertheless, both parameters were increased by AM colonization. In the same way, LsaHKT1;1, LsaHKT1;6, LsaNHX2, LsaNHX4, LsaNHX6 and LsaNHX8 genes and aquaporins PIP2 were up-regulated differentially by both AM fungi. The improved plant growth was closely related to a higher water status due to increased PIP2 abundance, as well as to the upregulation of LsaNHX gene expression, which concomitantly improved plant nutrition and K+/Na+ homeostasis maintenance.


Subject(s)
Aquaporins , Cation Transport Proteins/genetics , Lactuca/microbiology , Lactuca/physiology , Mycorrhizae/physiology , Salinity , Aquaporins/genetics , Cations , Chile , Fungi/physiology , Gene Expression Regulation, Plant , Plant Roots/microbiology , Symbiosis
16.
Environ Technol ; 41(11): 1358-1365, 2020 Apr.
Article in English | MEDLINE | ID: mdl-30301410

ABSTRACT

Organic micropollutants (OMP) in the household and industrial wastewater are not efficiently removed by conventional treatment processes and a significant fraction ends in sludge. Proper valorization technologies become fundamental to attain sustainable sewage sludge management, with anaerobic digestion (AD) as one of the preferred strategies. However, it exhibits some limitations that can be overcome with pre-treatment processes. In this study, the influence of different pre-treatment configurations over OMP concentration and removal during AD was assessed. The incorporation of a sequential US - TT-PT resulted in decreased concentrations of 7 of the 9 detected compounds in biosolids compared to conventional AD digestate, with bisphenol-A and ter-octylphenol showing the opposite effect. The results suggest that the assessed PT could improve the removal of sequestered or highly hydrophobic compounds through their solubilization and increased bioavailability.


Subject(s)
Sewage , Waste Disposal, Fluid , Anaerobiosis , Hydrolysis , Wastewater
17.
Article in English | MEDLINE | ID: mdl-31698987

ABSTRACT

The objective of this research was to evaluate the distribution of the molecular weights of the recalcitrant organic matter contained in kraft mill effluents and identify microbial consortia responsible for an anaerobic biodegradable fraction. As a result, the average removal efficiencies of chemical organic demand (COD) and biological oxygen demand (BOD5) during the entire period of operation were 28% and 53%, respectively. The non-biodegradable organic matter was detected at molecular weights less than 1000 Da. However, most of the organic matter was in the molecular weight fraction higher than 10000 Da with 32 ± 11.6% COD as well as color (42.3 ± 8.7%), total phenolic compounds (35.9 ± 7.9%) and adsorbable organic compounds (AOX) (13.0 ± 2.7%). Methanogenic acetoclastic archaea of the genera Methanomethylovorans and Methanosarcina were found in the surface and middle zones of the reactor. Moreover, Methanosaeta and Methanolinea were identified in the low zone of the reactor. In all zones of the reactor, Desulfomicrobium and Desulfovibrio were found to be the most dominant genera of sulfate-reducing bacteria (SRB).


Subject(s)
Industrial Waste/analysis , Microbial Consortia , Organic Chemicals/chemistry , Organic Chemicals/metabolism , Paper , Anaerobiosis , Archaea/classification , Archaea/genetics , Archaea/isolation & purification , Archaea/metabolism , Bacteria/classification , Bacteria/genetics , Bacteria/isolation & purification , Bacteria/metabolism , Biological Oxygen Demand Analysis , Bioreactors , Microbial Consortia/genetics , Molecular Weight , Waste Disposal, Fluid
18.
Electron. j. biotechnol ; Electron. j. biotechnol;39: 61-66, may. 2019. graf, tab
Article in English | LILACS | ID: biblio-1052032

ABSTRACT

BACKGROUND: Triclosan (TCS) is an antimicrobial agent widely used in health care and consumer products. This compound is present in sludge of wastewater treatment plants (WWTPs), and because of its bactericidal characteristics, it can inhibit the methanogenic activity in anaerobic digestion (AD) technology. The aim of this study was to evaluate the toxic effects of TCS on the methanogenic activity. RESULTS: Batch anaerobic reactors were used with TCS concentrations of 7.8, 15.7, 23.5, and 31.4 mg/L. These assays consisted in three successive feedings (I, II, and III), wherein the sludge was exposed to each TCS concentration and volatile fatty acid (VFA) substrate. For evaluation of the residual sludge activity during feeding III, only VFA was used. The results showed that the increase in TCS concentrations correlated with the reduction in methane (CH4) production. In this case, the minimum values were achieved for TCS concentration of 31.4 mg/L with CH4 levels between 101.9 and 245.3 during feedings I, II, and III. Regarding the effect of TCS on VFA consumption, an inhibitory effect was detected for TCS concentrations of 23.5 and 31.4 mg/L, with concentrations of acetic, butyric, and propionic acids at the end of the assay (37 d) between 153.6 and 206.8, 62.5 and 60.1, and 93.4 and 110 mg/L, respectively. Regarding the removal of TCS during AD, these values were above 47%. Conclusion: TCS is an inhibitor of methanogenic activity with a decrease between 63 and 70% during the different feedings. The CH4 production was not recovered during feeding III, with inhibition percentages of 21­72%.


Subject(s)
Triclosan/toxicity , Anaerobic Digestion , Methane/metabolism , Anti-Infective Agents/toxicity , Sewage , Wastewater Treatment Plants , Chromatography, High Pressure Liquid , Fatty Acids, Volatile , Anaerobiosis
19.
Sci Total Environ ; 648: 1042-1051, 2019 Jan 15.
Article in English | MEDLINE | ID: mdl-30340252

ABSTRACT

Organic matter removal in a horizontal subsurface flow constructed wetland (HSSF) treating wastewater is associated with the presence of bacteria and archaea. These organisms perform anaerobic microbial processes such as methanogenesis, which can lead to methane emissions. The aim of this study was to evaluate methane production and characterize the bacterial and archaeal communities found in HSSFs treating secondary urban wastewater during cold and warm seasons. The pilot system used in this study corresponds to four HSSFs, two planted with Phragmites australis (HSSF-Phr) and two planted with Schoenoplectus californicus (HSSF-Sch), the monitoring was carried out for 1335 days. Removal efficiencies for organic matter (biological and chemical oxygen demand) and total and volatile suspended solids were evaluated in each HSSF. Moreover, biomass from each HSSF was sampled during warm and cold season, and methane productions determined by Specific Methanogenic Activity assays(maximum) (SMAm). In the same samples, the quantification and identification of bacteria and archaea were performed. The results showed that the degradation of organic matter (53-67% BOD5 and 51-62% COD) and suspended solids (85-93%) was not influenced by seasonal conditions or plant species. Potential methane production from HSSF-Sch was between 20 and 51% higher than from HSSF-Phr. Moreover, potential methane production during warm season was 3.4-42% higher than during cold season. The quantification of microorganisms in HSSFs, determined greater development of bacteria (38%) and archaea (50-57%) during the warm season. In addition, the species Schoenoplectus californicus has a larger number of bacteria (4-48%) and archaea (34-43%) than Phragmites australis. The identification of microorganisms evidenced the sequences associated with bacteria belong mainly to Firmicutes (42%), Proteobacteria (33%) and Bacteroidetes (25%). The archaea were represented primarily by Methanosarcinales, specifically Methanosaeta (75%) and Methanosarcina (16%). The community structure of the methanogenic archaea in HSSFs did not change throughout the seasons or plant species.


Subject(s)
Archaea/physiology , Methane/metabolism , Wetlands , Archaea/metabolism , Bacteria/metabolism , Bacterial Physiological Phenomena , Chile , Cyperaceae/growth & development , Poaceae/growth & development , Seasons , Waste Disposal, Fluid/methods , Wastewater/analysis
20.
Int J Phytoremediation ; 20(6): 530-537, 2018 May 12.
Article in English | MEDLINE | ID: mdl-29688050

ABSTRACT

The aim of this study is to evaluate the influence of Agapanthus africanus (A. africanus) on nitrification in a vertical subsurface flow constructed wetlands (VSSFs) system. Two lab-scale VSSFs were operated: a) one was planted with A. africanus (vertical flow planted, VFP), and b) the other was unplanted (vertical flow control, VFC). The operation strategy was divided into three phases and consisted of increasing the ammoniacal nitrogen loading rate (ALR) (Phase I: 1.4; Phase II: 2.4; Phase III: 4.4 g NH4+-N·m-2·d-1). Nitrification was evaluated in the system at two different depths in the VSSFs (30.5 cm and 60.3 cm, from the top of the system). The removal efficiencies of COD, BOD5, TP, and PO4-3-P were above 40% in the VFP and VFC during all operation. The mean removal efficiencies of NH4+-N were above 70%. Nitrification was the principal NH4+-N removal mechanism in both systems and transformed more than 50% of the NH4+-N to NO3--N. In terms of the effect of A. africanus on NH4+-N removal during the three operational phases, nonsignificant differences between the two VSSFs were noted (p > 0.05). Thus, A. africanus did not influence nitrification. Finally, the analysis at different depths showed that nitrification occurred in the upper 30.5 cm.


Subject(s)
Nitrification , Wetlands , Biodegradation, Environmental , Nitrogen , Plants , Waste Disposal, Fluid
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