Influence of recirculation over COD and N-NH4 removals from landfill leachate by horizontal flow constructed treatment wetland

Abstract

Treatment of landfill leachate is a challenge due to its complex chemical composition and high recalcitrance and because of high costs for conventional wastewater treatment. In our study, leachate from the Quitaúna Landfill, Sao Paulo Metropolitan Region, Brazil, was treated at a laboratory scale with a horizontal subsurface flow constructed treatment wetland (HF-CTW) operating under a recirculation regime. Two units planted with Heliconia psittacorum (HP) and Cyperus papyrus (CP), and one unplanted control unit were assessed. With a recirculation regime over 21?days, the planted units removed 40% of chemical oxygen demand (COD) while the control unit removed only 29%. True color removal efficiencies were 2, 22, and 23% for the control, HP, and CP HF-CTWs, respectively. The ammonium nitrogen removal efficiencies for a 21-day hydraulic retention time (HRT) were 63–81% for planted units and 72% for the control. The increase of the HRT from 7 to 21?days led to the enhancement of ammonium nitrogen removal but did not affect the COD and total nitrogen removals. This phenomenon is a consequence of leachate’s low biodegradability. The present study shows the importance of the HRT and plant presence for landfill leachate treatment using HF-CTWs.     

Prévalence d'Aeromonas spp. dans les gastro-entérites de l'enfant.

A selective medium and biochemical tests were used to search for Aeromonas spp. in the stools of 536 children, more than 90% of whom had "gastroenteritis", seen at Sainte-Justine Hospital, Montreal, in June or July 1986. The organism was found in seven children, six of whom had bloody diarrhea. One of the six, a 6 1/2-year-old boy, required intravenous alimentation and later manifested ulcerative colitis; the other five recovered. The remaining child, a 14-year-old boy, had synovitis of the knee and spondylarthritis. Two of the seven carried other enteric pathogens. The authors discuss the pathogenicity of Aeromonas spp., which is not very marked in temperate climates, in human summer diarrhea and its possible role in the development of ulcerative colitis.     

A comparative study of surface and subsurface flow constructed wetlands for treatment of combined sewer overflows: A greenhouse experiment

The use of surface flow (SFCWs) and subsurface flow constructed wetlands (SFCWs) for the treatment of combined sewer overflows was assessed at pilot scale. Synthetic wastewater was applied in three batches with decreasing concentrations to mimic concentration profiles that are obtained in the field during overflow events. Three simulated combined sewer overflows were applied on each wetland. Composite water samples (60 in total) were taken for a period of 8 days to study the removal of total nitrogen (Ntot), NH₄–N, NO₃–N, total COD (CODtot) and total phosphorus. Redox potential, which was monitored at various locations along the wetlands, was more negative in the SSFCWs. In general, removal occurred faster in the SSFCWs and the final concentrations were lower. The removal of Ntot was only 36.6 ± 3.3% in the SFCWs due to nitrification-limiting conditions. The conditions in the SSFCWs, in contrast, seemed to promote Ntot removal (removal efficiency 96.7 ± 1.9%). The removal of P was hampered in both wetland types by reducing conditions. P that was initially removed was released again from the substrates later on. First-order removal rate constants were derived for the removal of both CODtot (SSFCWs: 1.1 ± 0.3 m d^?1; SFCWs: 0.17 ± 0.06 m d^?1) and Ntot (SSFCWs: 0.4 ± 0.1 m d^?1; SFCWs: 1.7 ± 0.5 m d^?1).     

Assessment of Micro-Basin Tillage as a Soil and Water Conservation Practice in the Black Soil Region of Northeast China

Micro-basin tillage is a soil and water conservation practice that requires building individual earth blocks along furrows. In this study, plot experiments were conducted to assess the efficiency of micro-basin tillage on sloping croplands between 2012 and 2013 (5°and 7°). The conceptual, optimal, block interval model was used to design micro-basins which are meant to capture the maximum amount of water per unit area. Results indicated that when compared to the up-down slope tillage, micro-basin tillage could increase soil water content and maize yield by about 45% and 17%, and reduce runoff, sediment and nutrients loads by about 63%, 96% and 86%, respectively. Meanwhile, micro-basin tillage could reduce the peak runoff rates and delay the initial runoff-yielding time. In addition, micro-basin tillage with the optimal block interval proved to be the best one among all treatments with different intervals. Compared with treatments of other block intervals, the optimal block interval treatments increased soil moisture by around 10% and reduced runoff rate by around 15%. In general, micro-basin tillage with optimal block interval represents an effective soil and water conservation practice for sloping farmland of the black soil region.     

A network-informed analysis of SARS-CoV-2 and hemophagocytic lymphohistiocytosis genes’ interactions points to Neutrophil extracellular traps as mediators of thrombosis in COVID-19

Abnormal coagulation and an increased risk of thrombosis are features of severe COVID-19, with parallels proposed with hemophagocytic lymphohistiocytosis (HLH), a life-threating condition associated with hyperinflammation. The presence of HLH was described in severely ill patients during the H1N1 influenza epidemic, presenting with pulmonary vascular thrombosis. We tested the hypothesis that genes causing primary HLH regulate pathways linking pulmonary thromboembolism to the presence of SARS-CoV-2 using novel network-informed computational algorithms. This approach led to the identification of Neutrophils Extracellular Traps (NETs) as plausible mediators of vascular thrombosis in severe COVID-19 in children and adults. Taken together, the network-informed analysis led us to propose the following model: the release of NETs in response to inflammatory signals acting in concert with SARS-CoV-2 damage the endothelium and direct platelet-activation promoting abnormal coagulation leading to serious complications of COVID-19. The underlying hypothesis is that genetic and/or environmental conditions that favor the release of NETs may predispose individuals to thrombotic complications of COVID-19 due to an increase risk of abnormal coagulation. This would be a common pathogenic mechanism in conditions including autoimmune/infectious diseases, hematologic and metabolic disorders.     

Intérêt des traceurs de l’hypoxie en radiothérapie

Tumor hypoxia is a major parameter of radioresistance. Hypoxia PET imaging using several radiotracers (F-Miso, FAZA, Cu-ATSM, EF5…) may help predict response to radiotherapy. Hypoxic area evaluation may also help select patients for hypoxia-targeting drugs, and thus reinforcing radiotherapy effects. Hypoxia imaging may also be fused with radiotherapy planning CT to define radioresistance areas that may be boosted by dose-painting radiotherapy. Despite several difficulties (patient positioning, organ and tumor motion, image definition…), targeting hypoxic regions within tumors is one of the most promising research strategies of modern radiotherapy.     

Trypanosoma brucei gambiense Infections in Mice Lead to Tropism to the Reproductive Organs,and Horizontal and Vertical Transmission

Trypanosoma brucei gambiense, transmitted by the tsetse fly, is the main causative agent of Human African trypanosomosis in West Africa and poses a significant health risk to 70 million people. Disease progression varies depending on host immunity, but usually begins with a haemo-lymphatic phase, followed by parasite invasion of the central nervous system.In the current study, the tropism of T. b. gambiense 1135, causing a low level chronic ‘silent’ infection, was monitored in a murine model using bioluminescence imaging and PCR. A tropism to the reproductive organs, in addition to the central nervous system, after 12–18 months of infection was observed. Bioluminescent analysis of healthy females crossed with infected males showed that 50%, 62.5% and 37.5% of the female mice were subsequently positive for parasites in their ovaries, uteri and brain respectively. Although PCR confirmed the presence of parasites in the uterus of one of these mice, the blood of all mice was negative by PCR and LAMP. Subsequently, bioluminescent imaging of the offspring of infected female mice crossed with healthy males indicated parasites were present in the reproductive organs of both male (80%) and female (60%) offspring.These findings imply that transmission of T. b. gambiense 1135 occurs horizontally, most probably via sexual contact, and vertically in a murine model, which raises the possibility of a similar transmission in humans. This has wide reaching implications. Firstly, the observations made in this study are likely to be valid for wild animals acting as a reservoir for T. b. gambiense. Also, the reproductive organs may act as a refuge for parasites during drug treatment in a similar manner to the central nervous system. This could leave patients at risk of a relapse, ultimately allowing them to act as a reservoir for subsequent transmission by tsetse and possibly, horizontally and vertically.     

Direct and Indirect Effects of Forest Anthropogenic Disturbance on Above and Below Ground Communities and Litter Decomposition

Ecosystems - Direct and indirect effects of habitat modification and changes in biotic interactions should be taken into consideration to understand the ecological consequences of forest...     

Étude de faisabilité du ganglion sentinelle dans le cancer de la prostate par cœlioscopie : premiers résultats

Objectives

The standard lymphadenectomy is currently a challenge in the management of prostate cancer. The aim of this prospective study was to evaluate the performance of the sentinel lymph node (SLN) by laparoscopy in patients with localized prostate cancer, candidates for local treatment.

Patients and methods

Patients were injected transrectal ultrasound-guided with 0.3 mL/100MBq 99^mTc-Sulfur rhenium colloid in each prostatic lobe, the day before surgery. Lymphoscintigraphy was performed after 2 hours. The detection was realized intraoperatively with a laparoscopic probe (Gamma Sup Clerad^®) followed by extensive dissection. Counts of SLN were performed in vivo and confirmed ex vivo. The histological analysis was performed by HPS staining and followed by immunochemistry if SLN was free.

Results

Seventy patients with carcinoma of the prostate at intermediate or high risk of lymph node metastases (D’Amico), PSA median 9.5 ng/mL [6–130], were included in the study. The lymphoscintigraphic detection rate was 94.2% (66/70) and intraoperative of 97.0% (68/70). Fourteen patients had lymph node metastases, six only in SLN. The false negative rate was 2/14 (14.0%). The internal iliac region is the first metastatic site (40.9%). Limited or standard lymph node dissection would have ignored respectively 72.7% and 59.0% of lymph node metastases.

Conclusion

The laparoscopy is adapted to a broad identification of SLN and targeted dissection of these lymph nodes significantly limits the risk of surgical extended dissection while maintaining the accuracy of the information.