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•Low COD/N could improve nitrogen removal of SPN/A.•AMX activity was decreased without influent COD.•The microbial distribution difference between granules/flocs was ...observed.•Biodiversity of AOB and NOB increased with COD/N decreasing at low DO (0.2mgL−1).
This study investigates the effects of varying COD/N ratios on single-stage partial nitritation/anammox (SPN/A) process in a SBR. The operational period was divided into three phases with different influent COD/N ratios (0.4, 0 and 0.5). Stable nitrogen removal was achieved in phase I with a COD/N of 0.4. In phase II COD was absent, effluent nitrite and nitrate increased and nitrogen removal performance gradually deteriorated. In phase III SPN/A failed to recover from nitrate accumulation when COD/N was increased. Microbial activity was measured and microbial community was analyzed by high-throughput sequencing. These results revealed that ordinary heterotrophic organisms (OHO) was suppressed when influent COD was absent, leading to the promotion of nitrification even at a low DO (0.2mgL−1). Therefore, nitrite oxidizing bacteria (NOB) was gradually enriched and anammox bacteria was suppressed. Besides, it was observed that flocs were sensitive to influent COD variations than granules, which requires further investigation.
The presence of nitrate in the theoretical anaerobic reactor of a municipal WWTP aiming at simultaneous C, N and P removal usually leads to Enhanced Biological Phosphorus Removal (EBPR) failure due ...to the competition between PAO and denitrifiers for organic substrate. This problem was studied in a continuous anaerobic–anoxic–aerobic (A
2/O) pilot plant (146 L) operating with good removal performance and a PAO-enriched sludge (72%). Nitrate presence in the initially anaerobic reactor was studied by switching the operation of the plant to an anoxic–aerobic configuration. When the influent COD composition was a mixture of different carbon sources (acetic acid, propionic acid and sucrose) the system was surprisingly able to maintain EBPR, even with internal recycle ratios up to ten times the influent flow rate and COD limiting conditions. However, the utilisation of sucrose as sole carbon source resulted in a fast EBPR failure. Batch tests with different nitrate concentrations (0–40 mg L
−1) were performed in order to gain insight into the competition for the carbon source in terms of P-release or denitrification rates and P-release/C-uptake ratio. Surprisingly, no inhibitory or detrimental effect on EBPR performance due to nitrate was observed. A model based on ASM2d but considering two step nitrification and denitrification was developed and experimentally validated. Simulation studies showed that anaerobic VFA availability is critical to maintain EBPR activity.
► The carbon source nature is essential in the competition between PAO-denitrifiers. ► With a VFA-based feed, PAO outcompeted OHO even under an anoxic–aerobic configuration. ► EBPR failed when a more complex compound (sucrose) was used as a sole carbon source. ► The NO
X
presence prevented the sucrose fermentation process for the VFA production. ► A model showed that VFA presence was the key point to trigger off EBPR activity.
Tannery wastewater effluent (TWE) consists of a variety of complex structured compounds having very low biodegradability. Few attempts have been made to treat real-time TWE consisting of complex ...compounds and find the intermediate compounds formed during the HC+PAA+ FeSO4.7 H2O treatment system. Therefore, a pilot scale study has been conducted on an orifice-embedded hydrodynamic cavitation reactor for treating real-time TWE. Liquid chromatography-high resolution mass spectrometry (LC-HRMS) has been carried out to identify the specific compounds present in TWE before and after treatment. Response surface methodology (RSM) – Box-Behnken design (BBD) obtained maximum COD, TDS and turbidity removal efficiency of 72.36%, 94.54% and 98.89%, respectively, at cavitation time-97.5 min, inlet pressure-7.5 bar, pH-2, orifice diameter-0.5 mm, PAA dosage-17.5 g/L, and PAA /FeSO4.7 H2O-2:1 ratio. The reaction rate constant was increased from 2.455 × 10−3 to 12.75 × 10−3 min−1 when AOPs were combined with HC. The study concluded that the degradation using HC+PAA+ FeSO4.7 H2O successfully increased the biodegradability of the TWE without forming any toxic by-products.
•Optimization studies using RSM-Box Behnken design is performed in the study.•The formation and collapse of cavities depends upon geometry of orifice.•Hydroxyl radical generation is responsible for decomposition of tannery wastewater.•Overall cost and energy required for hydrodynamic cavitation system is elaborated.•Chemical oxygen demand decreased by 72% using HC+PAA+ FeSO4.7H2O treatment system.
«¿Cómo aquel que viene y el que acoge ... construyen un mundo común? ¿Qué visiones del cosmopolitismo contemporáneo nos ofrece la literatura actual?». Tales son las preguntas a las que el presente ...artículo trata de dar respuesta, relacionando las nociones de «cosmopolitismo ordinario» (Agier, 2019) y de «mundo común» (Tassin, 2003) para proponer el concepto de «cosmopolitismo transmigratorio». En efecto, mediante el análisis de Mur Méditerranée de Louis-Philippe Dalembert (2019) y Les Lumieres d'Oujda de Marc Alexandre Oho Bambe (2020), se tratará de demostrar que una poética pragmática involucra al lector en un cosmopolitismo del actuar, decididamente horizontal, lejos de las asignaciones identitarias, de las miradas dominantes, de las obsesiones nacionales, que aspira a hacer mundo de manera colectiva y políticamente.
The anaerobic-anoxic-oxic (AAO) process is one of the most widely used processes for treating industrial organic wastewater, and it has shown significant effectiveness in the removal of organic ...compounds, as well as denitrification and phosphorus removal. However, for the treatment of industrial organic wastewater, this anaerobic preposition and aerobic postposition process has exposed various limitations. Therefore, for this type of wastewater, the oxic-hydrolytic and denitrification-oxic (OHO) treatment process has been proposed and developed based on the principles of three-sludge separation and fluidization. This study integrated operational data from 203 coking wastewater treatment plants worldwide, and the two-step nitrification-denitrification activated sludge model No.3 (TCW-ASM3) was used for comparative analysis of the pollutant removal efficiency and total operating cost of the AAO process and the OHO process in the face of characteristic pollutants in coking wastewater. The results indicate that the full-scale OHO process achieved removal efficiencies of up to 3784 mg/L for chemical oxygen demand (COD) and 297 mg/L for total nitrogen (TN). The theoretical total cost for OHO and AAO were 9.75 and 14.38 CNY/m3, respectively. The pre-treatment aerobic process effectively reduces the biological toxicity of high-toxicity and refractory industrial wastewater, and the three-sludge system provides a stable living space for functional microorganisms, the combination of multi-mode denitrification processes offers new possibilities for treating similar types of industrial wastewater.
Oho-dake volcano, situated at the central part of the Shimokita peninsula, Northeast Japan, is a small Quaternary composite volcano consisting of coexisting tholeiitic and calc-alkaline andesitic to ...dacitic lavas and pyroclastic flow deposits. Two K-Ar ages (1.99±0.08Ma and 2.03±0.08Ma) were obtained from the uppermost part and lower part of lava flows, which overlap within the estimated errors. Small volume eruptions of Oho-dake volcano are consistent with small and short-lived magma batches within the magma plumbing system.
From December 27 to 28, 2014, using the deep sea survey system DEEP TOW on the Research Vessel “Yokosuka” YK 14-22 cruise (KO-OHO-O cruise IV), Japan Agency for Marine-Earth Science and Technology ...(JAMSTEC), we conducted submarine surveys at the Sagami Knoll in the Sagami Bay in twice (YKDT # 160, # 161), and at the branch of the Iro Submarine Canyon in the southern Izu Peninsula offshore (YKDT # 162). In the Sagami Knoll, the survey was made along the steep slope of the south side of the Knoll and the dive started from the middle terrace and then progressed in the direction of rising along the slope. The slope consists mainly of mudstone, but three to four layers of conglomerate were found therein. Ten rock samples were collected by the dredgers during the dive (YKDT # 161). In the branch of the Iro Submarine Canyon, diving started from the downstream side, focusing on the stricture part of the canyon midstream, passing through the narrowing toward upstream, and finally rose up the ridge-like topography of the narrowing. Outcrops were widely observed near the stricture, where were found the conglomeratic body in the lower and the layered and massive complex in the upper. The valley floor of the stricture part was sandy and/or pebbly and ripple marks were widely observed on the sea floor. Those ripple marks show the flow direction mostly from the downstream side to the upstream side. It is not a normal flow along the canyon, and infers some flow due to bottom current. On the basis of the rock samples collected in this submarine survey, we examined the compositions of volcanic rocks and confirm that they are andesite to dacite.
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