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Improper disposal of arsenic-rich biomass and the lack of efficient methods to treat it may cause contamination in the environment. We developed an efficient method for arsenic (As) removal and biomass reduction of As-rich biomass of the As-hyperaccumulator Pteris vittata by coupling ethanol extraction with anaerobic digestion. This study assessed As partitioning among the three phases (gas, liquid and solid) after anaerobic digestion of P. vittata biomass. Biomass with and without As was first extracted with ethanol. Ethanol extraction removed ~93% As, with remaining As concentration at 197 mg kg -1 . The extracted biomass was then digested at 35 °C under anaerobic conditions for 35 d. Arsenic in the digested biomass was reduced by 89%, with remaining As concentration at 60 mg kg -1 . In addition, anaerobic digestion reduced the biomass by 64-71% and decreased the volatile solids content from 94 to 15-18%. Methane production was 145 and 160 L N CH 4 /kgVS after 35 d for As-rich and control biomass, respectively. As a final step, As concentration in anaerobic digestate supernatant was reduced to 0.26 mg L -1 by As-Mg precipitation. Overall, coupling ethanol extraction with anaerobic digestion decreased As concentration in P. vittata biomass from 2665 to 60 mg kg -1 , or by 98%. At this level (<100 mg As kg -1 ), P. vittata biomass can be considered a safe material based on USEPA regulations. Effective As removal from P. vittata biomass prior to disposal improves the phytoremediation process and lowers biomass transport and landfill disposal costs., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Abstract: Fourier Transform Infra-Red (FTIR) spectroscopy was used to investigate whether algae belonging to the green evolutionary lineage and algae belonging to the red evolutionary lineage consistently differ for their biomass composition and for the way their composition responds to changes in NO3 − availability. For this purpose, the FTIR spectra of eleven algal species cultured in media containing different amount of NO3 − were subjected to Hierarchical Cluster Analysis (HCA). The same analysis was conducted on the differential FTIR spectra of cells grown at different NO3 − concentrations. Although the organic composition of cells was affected by the availability of NO3 −, the analysis of its change did not elicit a clear relationship with the phylogenetic position of the species used. However, when the two evolutionary lineages, and not the individual species, are compared, some differences emerge: the species belonging to the green lineage reorganize their biomass composition similarly in response to variations in N availability, whereas the species of the red lineage modulate their allocation patterns more heterogeneously. This difference may contribute to the ecological fitness of microalgae and may have had an influence on the evolutionary trajectories of phytoplankton groups. [Copyright &y& Elsevier]

Records of effects of ambient ozone pollution on vegetation have been compiled for Europe for the years 1990-2006. Sources include scientific papers, conference proceedings, reports to research funders, records of confirmed ozone injury symptoms and an international biomonitoring experiment coordinated by the ICP Vegetation. The latter involved ozone-sensitive (NC-S) and ozone-resistant (NC-R) biotypes of white clover ( Trifolium repens L.) grown according to a common protocol and monitored for ozone injury and biomass differences in 17 European countries, from 1996 to 2006. Effects were separated into visible injury or growth/yield reduction. Of the 644 records of visible injury, 39% were for crops (27 species), 38.1% were for (semi-) natural vegetation (95 species) and 22.9% were for shrubs (49 species). Owing to inconsistencies in reporting effort from year to year it was not possible to determine geographical or temporal trends in the data. Nevertheless, this study has shown effects in ambient air in 18 European countries from Sweden in the north to Greece in the south. These effects data were superimposed on AOT40 (accumulated ozone concentrations over 40 ppb) and POD3 (modelled accumulated stomatal flux over a threshold of 3 nmol m s) maps generated by the EMEP Eulerian model (50 km × 50 km grid) that were parameterized for a generic crop based on wheat and NC-S/NC-R white clover. Many effects were found in areas where the AOT40 (crops) was below the critical level of 3 ppm h. In contrast, the majority of effects were detected in grid squares where POD3 (crops) were in the mid-high range (>12 mmol m). Overall, maps based on POD3 provided better fit to the effects data than those based on AOT40, with the POD3 model for clover fitting the clover effects data better than that for a generic crop. [ABSTRACT FROM AUTHOR]

A pilot-scale membrane bioreactor was operated for advanced treatment of secondary effluent from a wastewater treatment plant. The performance and biomass characteristics were evaluated under two different hydraulic retention time (HRT) values (7.5 and 15 hours). The system was operated successfully without biomass purge and, after an initial phase, evolved until reaching a constant mixed-liquor volatile suspended solids (MLVSS) concentration, which resulted in the same value of carbon utilization rate (0.067 ± 0.004 kg COD kg-1 MLVSS d-1) for both HRTs. Respiration tests (maximum and endogenous oxygen uptake rates) confirmed a low microbial activity, which approached constant values (0.132 ± 0.001 and 0.064 ± 0.007 g O2 g-1 MLVSS d-1, respectively), regardless of the HRT. The sludge morphology and bound and supernatant extracellular polymeric substances also were assessed. Membrane performance was characterized by a stable behavior occurring simultaneously with a high level of biodegradation in the microcolloidal and soluble fraction. [ABSTRACT FROM AUTHOR]

Summary: Pseudomonas corrugata, a soil bacterium originally isolated from a temperate site of Indian Himalayan Region (IHR) is examined for its antagonistic activities against two phytopathogenic fungi, Alternaria alternata and Fusarium oxysporum. Although the bacterium did not show inhibition zones due to production of diffusible antifungal metabolites, a reduction in growth between 58% and 49% in both test fungi, A. alternata and F. oxysporum, was observed in sealed Petri plates after 120h of incubation due to production of volatile antifungal metabolites. Reduction in biomass of A. alternata (93.8%) and F. oxysporum (76.9%) in Kings B broth was recorded after 48h of incubation in dual culture. The antagonism was observed to be affected by growth medium, pH and temperature. The reduction in fungal biomass due to antagonism of bacteria was recorded maximum in the middle of the stationary phase after 21h of inoculation. The production of siderophore, ammonia, lipase and chitinase in growth medium by P. corrugata were considered contributing to the antagonistic activities of the bacterium. [Copyright &y& Elsevier]

Pilot-scale experiments were continuously carried out for more than 9 months to study the excess biomass reduction effect using a biophase-separation bioreactor, which was designed based on food-chain theory. By separating the biophase in the wastewater treatment system, bacteria, protozoa, and metazoa could be separated from each other and dominated in different microbial communities. After degrading organic matter, bacteria were consumed by protozoa or metazoa in the following process in such a reactor. Thus, both chemical oxygen demand (COD) and biomass were reduced. During the process of treating restaurant wastewater, the excess biomass yield in this biophase-separation technique varied from 0.13 to 0.22 kg/kg COD removed, 50% lower than that from the reference system. Apart from low biomass production, this biophase-separation technique can simultaneously achieve a high COD removal efficiency and improve settleability of biosolids at a hydraulic retention time of 6 to 13 hours. [ABSTRACT FROM AUTHOR]

Depuration is a common practice in aquatic organisms culture. The exposure time of animals to the treated water is one of the most important factors for efficiency and can affect their biomass. The effect of depuration in Pomacea patula adults using the condition index (IC) was evaluated under laboratory conditions. Cultured adults snails were maintained in clean aquaria and exposed to a constant flow water treated with ultraviolet radiation (Group 1), meanwhile that Group 2 was kept under normal culture conditions. There were 5 replicates per group. The wet weight and total length was obtained individually, at the beginning and after the depuration time of 10 days. The mean correlation coefficient value (initial animals, Groups 1 and 2) was higher than 0.90. The initial IC (771.81 ± 40.41) and those for Group 1 and 2 (763.527 ± 25.24 and 765.465 ± 38.59, respectively) were not significant different (P > 0.05) at the end of the experiment. The results suggest that the depuration process used did not affect the adult P. patula biomass. The IC represented an useful tool for evaluation of depuration despite the differences found in the initial size of adult snails. [ABSTRACT FROM AUTHOR]

Abstract: Four Mediterranean tree taxa, Quercus ilex subsp. ilex, Quercus ilex subsp. ballota, Olea europaea cv. vulgaris and Ceratonia siliqua, were exposed to different ozone (O3) concentrations in open top chambers (OTCs) during 2 years. Three treatments were applied: charcoal-filtered air (CF), non-filtered air (NF) and non-filtered air plus 40 ppbv of O3 (NF+). The photochemical maximal efficiency, Fv/Fm, decreased in NF+ plants during the second year of exposure, especially during the most stressful Mediterranean seasons (winter and summer). An increase of δ13C was found in three of the four studied species during the first year of exposure. This finding was only maintained in C. siliqua during the second year. Decreases in the chlorophyll content were detected during the first year of fumigations in all the species studied, but not during the second year. The NF+ treatment induced changes in foliar anatomical characteristics, especially in leaf mass per area (LMA) and spongy parenchyma thickness, which increased in some species. A reduction in N content and an increase in δ15N were found in all species during the second year when exposed in the NF+ OTCs, suggesting a change in their retranslocation pattern linked to an acceleration of leaf senescence, as also indicated by the above mentioned biochemical and anatomical foliar changes. The two Q. ilex subspecies were the most sensitive species since the changes in N concentration, δ15N, chlorophyll, leaf area, LMA and biomass occurred at ambient O3 concentrations. However, C. siliqua was the most responsive species (29% biomass reduction) when exposed to the NF+ treatment, followed by the two Q. ilex subspecies (14–20%) and O. europaea (no significant reduction). Ozone resistance of the latter species was linked to some plant traits such as chlorophyll concentrations, or spongy parenchyma thickness. [Copyright &y& Elsevier]

Abstract: The effects of ozone (O3) exposure under different water availabilities were studied in two Mediterranean tree species: Quercus ilex and Ceratonia siliqua. Plants were exposed to different O3 concentrations in open top chambers (charcoal-filtered air (CF), non-filtered air (NF)) and non-filtered air plus 40ppbv of O3 ((7:00–17:00 solar time) (NF+)) during 2 years, and to different water regimes (IR, sample irrigation, and WS, reduced water dose to 50%) through the last of those 2 years. AOT40 in the NF+ treatment was 59265ppbvh (from March 1999 to August 1999) while in the NF treatment, the AOT40 was 6727ppbvh for the same period. AOT40 was always 0 in the CF treatment. WS plants presented lower stomatal conductances and net photosynthetic rates, and higher foliar N concentrations than IR plants in both species. The irrigation treatment did not change the response trends to ozone in Q. ilex, the most sensitive species to O3 ambient concentrations, but it changed those of C. siliqua, the least sensitive species, since its ozone-fumigated WS plants did not decrease their net photosynthetic rates nor their biomass accumulation as it happened to its ozone-fumigated IR plants. These results show interspecific variations in O3 sensitivity under different water availabilities. [Copyright &y& Elsevier]

In order to test the hypothesis that ozone-induced limitation of biomass production in juvenile silver birch (Betula pendula Roth) is driven by stomatal uptake of ozone (O3) rather than external exposure, biomass reduction was related to the cumulative uptake of O3 through stomata over an uptake cut-off threshold of x nmol O3 m-2 s-1 (CUO>x), to the accumulated exposure to O3 over a threshold of y nmol mol-1 during daylight hours (daylight AOTy) or during 24 h (24 h AOTy), and to the sum of daytime concentrations exceeding 60 nmol mol-1 (SUM06). The analysis included data from nine different experiments conducted in Sweden, Finland and Switzerland. Stomatal uptake of O3 was estimated using a stomatal conductance (gs) model including gs response functions for photosynthetic photon flux density, water vapour pressure deficit of the air and air temperature. Experiment-specific maximum gs (gmax) as well as gs in darkness (gdark) were assessed through local measurements. Biomass reduction was more strongly related to CUO>x than to SUM06 and daylight or 24 h AOTy, but the difference between CUO>x and 24 h AOTy was small. The better performance of CUO>x was dependent on the use of site- and experiment-specific gmax and gdark values, and there was a positive relationship between gmax and biomass reduction per unit AOT40. Daylight AOTy and SUM06 could not account for the growth limiting impact of nocturnal O3 uptake in the Swiss experiments. A sensitivity analysis revealed that the CUO>x estimates were largely insensitive to the estimate of the conductance for non-stomatal leaf surface deposition of O3, as a result of turbulent conditions at the experimental plots. In summary, we conclude that CUO>x was more successful in accounting for the variation in biomass reduction in juvenile birch as compared to indices based on external exposure, if gmax and gdark were locally parameterised. [Copyright &y& Elsevier]

Leaf or needle ozone uptake was estimated for young trees at seven experimental sites across Europe using a stomatal conductance simulation model. Dose–response relationships based on cumulative leaf uptake of ozone (CUO) were calculated using different hourly ozone flux thresholds and these were compared to dose–response relationships based on daylight AOT40, which is currently used within the UNECE Convention on Long-Range Transboundary Air Pollution (CLRTAP). Regression analysis showed that the CUO–biomass response relationships were highly significant for both coniferous and broadleaf trees, and independent of which ozone flux threshold was applied. On the basis of this regressions analysis, an hourly flux threshold of 1.6 nmol m−2 s−1 (CUO>1.6) is proposed as the most appropriate for all species categories in deriving dose–response relationships. The analysis indicated that the current critical level for ozone impacts on European forests of AOT40 10 ppm h may not protect the most sensitive receptors and that critical levels for AOT40 and CUO>1.6 of 5 ppm h and 4 mmol m−2, respectively, are more appropriate. The research identified weaker dose–response relationships for the CUO exposure index compared with AOT40. Distinguishing between sensitive and less sensitive species substantially improved the CUO–biomass response relationships although, still, to a lesser extent than when exposure was expressed as AOT40. [Copyright &y& Elsevier]

Clarification of municipal wastewater was shown to be improved significantly by the addition of cultured bdelloid rotifers. The rate and degree of suspended particle removal were correlated with rotifer number. The size range of unsettled particles suspended in wastewater was determined and found to overlap with the size range of particles consumed by rotifers. Rotifers were shown to have two distinct effects on suspended particles: consumption of biomass due to feeding activity; and improved settling, probably due to enhanced aggregation. These experiments demonstrate the potential for the use of bdelloid rotifers in an enhanced wastewater treatment process, with reduced biomass production and improved effluent clarity. [Copyright &y& Elsevier]

Summary • Species of fen and fen-meadow communities, well supplied with water and nutrients, are characterised by high rates of growth, stomatal conductance values and specific leaf areas, all factors which have been associated with high sensitivity to ozone. We therefore examined the effects of ozone on 12 characteristic fen and fen-meadow species. • Plants received either filtered air or ozone; AOT40 exposures ranged from 9200 to 14 300 ppb h. Eight of the 12 species exhibited foliar injury in response to ozone exposure, with the first signs of injury on Vicia cracca , following an AOT40 exposure of only 1950 pbb h. • Ozone exposure significantly reduced plant photosynthetic rate, stomatal conductance and biomass production in four species. Cirsium arvense exhibited the greatest biomass response to ozone (32% and 58% reduction in above- and below-ground weight, respectively). Species with higher levels of visible injury tended to show greater reductions in biomass. There was a significant positive association between stomatal conductance and the magnitude of ozone effects on root biomass. • The widespread occurrence of either visible injury or growth reductions amongst the species screened, and the magnitude of effects on the most sensitive species, indicate that species of fens and fen-meadows may be more sensitive to ozone than other seminatural ecosystems which have been the focus of recent ozone studies. [ABSTRACT FROM AUTHOR]

Reducing the energy available for anabolism of cell mass was identified as a method to minimise disposal requirements of excess biomass produced in the activated sludge process. A model system consisting ofPseudomonas putida, maintained in a chemostat, was employed to investigate biomass production in the presence of the energy dissipating protonphore, p-nitrophenol (pNP). The efficiency of biomass productionwas reduced by up to 62% when the feed was supplemented with 100 mg pNP-l-1 with a simultaneous increase in the specific substrate uptake rate. The data obtained have been analysed to reveal maintenance energy requirements and true growth yields. Cells were found to satisfy their maintenance energy requirements prior to utilising energy in anabolism. Decreases in pH alone had no effect on biomass production, but caused additional protonphore induced reduction of biomass production. A pH 6.2 the efficiency of biomass production was reduced by up to 77% when the feed was supplemented with 100 mg pNP-l-1. ) 1998 IAWQ. Published by Elsevier Science Ltd. [ABSTRACT FROM AUTHOR]

The activated sludge process is common for the treatment of wastewater. The process uses a mixed culture of microorganisms that degrade the wastewater aerobically producing carbon dioxide, water and new biomass. Some of the biomass produced is recycled and the rest requires disposal. Changing legislation, rising costs and increasing sludge production have caused a shift in emphasis from volume of wastewater turnover and maximal DOD removal to minimisation of the biomass produced. Low to zero yields are possible by extended aeration processes and raising process operating temperature but these involve large energy inputs. Manipulation of the activated sludge process to promote thegrowth of protozoa, nematodes, rotifers or oligochaeta reduces biomass production by predation of the microorganisms. Promotion of microorganism species that have a high maintenance energy by the provision of support matrices or increasing sludge retention time has the potential to prevent biomass accumulation. Uncoupling of microbial metabolic pathways by both transition from anaerobic to aerobic conditions and by chemical addition prevents biomass production successfully. Thealterations required for increasing retention times or introducing asecond bacterial predation chamber may not be feasible at established plants. The increased operation costs and capital works may not be economically viable. The most efficient and cost effective solution has yet to be optimised. [ABSTRACT FROM AUTHOR]