Modelling a Severe Transient Anoxia of Continental Freshwaters due to a Scheldt Accidental Release (Sugar Industry)

Most anthropogenic pollution can be controlled, such as domestic and industrial releases, loads from agriculture, etc. However, some of them, which are associated to illegal discharges, industrial accidents, etc., are more difficult to forecast. This study was performed on the Tereos sugar industry accident that occurred during the night of 9 April 2020, when 88,000 cubic meters of effluents loaded with organic matter discharged in the Scheldt River (a 350 km long transnational river that flows through Northern France and Western Belgium). The accident had dramatic consequences on the receiving watercourse, over 120 km downstream. Fish mortalities have been observed and severe deoxygenation, reaching zero concentration in dissolved oxygen, have impacted river chemical quality. The objective was to understand and describe the dynamics of the chemical pollution and its propagation along the transboundary hydrographic network of the Scheldt. A method based on the processes of organic matter degradation in the river ecosystem was enhanced. It is demonstrated that the accident is doubtless the cause of the water column deoxygenation. This paper shows how the water quality modelling can help to understand and therefore to prevent the consequences of accidental pollution on a river network.

An Experiment on Flashing-Spray Jet Characteristics of Supercritical CO2 from Various Orifice Geometries

Supercritical CO2 pipelines usually are used to link the CO2 capture system to the geological storage. There are severe hazards once the asphyxiating gas leaks from the long-distance pipeline. The uncertainty of near-field jet characteristics results in imprecise consequences assessment of accidental release of supercritical CO2. To improve the prediction of consequences of accidental release accuracy, the near-field mechanisms of flashing-spray jet was investigated. In this work, an experimental setup with multiple measurement instruments was developed to impose controllable CO2 release from a high-pressure vessel. The flashing-spray jet structures of supercritical CO2 from circular and rectangular orifices were recorded by a high-speed camera. Results indicate that the near-field structures of supercritical CO2 jet from circular and rectangular orifices are totally different, which causes the different dispersion consequences. The jet angle and shock waves were analyzed quantitatively. Lastly, the models of flashing-spray based on the two different phenomena from rectangular and circular orifices were discussed. The combination of macroscopic and microscopic data in the jet can help to understand the complex physics and improve discharge and dispersion model. This work provides a fundamental data to consequences assessment of accidental release of supercritical CO2.

Improving the Safety and Acceptability of Autocidal Gravid Ovitraps (AGO Traps)

ABSTRACT Gravid traps that collect eggs or adult mosquitoes use color, size, or volume as well as water or plant infusions as attractants. Biorational larvicides have been used to prevent these devices from producing adult mosquitoes within the traps. Results from field assays on the use of several biorational larvicides for various mosquito species have provided mixed results in terms of increased, neutral, or reduced attraction. We investigated the use of Bacillus thuringiensis var. israelensis, spinosad, and novaluron in field assays in Puerto Rico to evaluate the behavioral response of Aedes aegypti and Culex spp. to autocidal gravid ovitraps (AGO traps). The purpose of the study was to increase the safety of these traps by preventing accidental release of adult mosquitoes when traps are opened or damaged. We also investigated whether trap color (blue, green, terracotta) that may be more amenable for use by residents in their properties induced a similar attraction response to the original black trap color. We found that the use of biorational larvicides did not significantly change the behavioral attraction of these mosquito species to AGO traps. For Ae. aegypti, green traps yielded the lowest captures while black, terracotta, and blue produced similar higher yields. Culex spp. in black traps showed significantly higher captures compared with other colors. These results suggest that black, terracotta, or blue AGO traps can be used for the surveillance and control of Ae. aegypti.

Phytotoxicity of Nanomaterials in Agriculture

Science and technology have advanced rapidly in every aspect; thus, nanotechnology is one of the highly promising interdisciplinary approaches which has swiftly emerged in the world. The inherent properties of nanomaterials (NMs) made them widely accepted to use in many fields, including agriculture. Because of this, NMs have attracted novel agrochemical formulations to enhance crop productivity. However, deliberate and accidental release of nanoparticulate based agrochemical formulations and engineered NMs have raised concerns on the possible effects on agricultural crops. Therefore, the interaction of NMs leading to phytotoxicity is the biggest concern that is required to be assessed prior to their applications. Hence, this review discusses whether NMs can be used as a feasible stand-in candidate for agriculture.

Investigation of LNG Underwater Release and Combustion Behavior on Water Surface

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 30646, “Experimental Investigation of LNG Underwater Release and Combustion Behavior on the Water Surface,” by Yixiang Zhang, Jianlu Zhu, and Youmei Peng, China University of Petroleum, et al., prepared for the 2020 Offshore Technology Conference, originally scheduled to be held in Houston, 4-7 May. The paper has not been peer reviewed. Copyright 2020 Offshore Technology Conference. Reproduced by permission. Most liquefied natural gas (LNG) is transported by ship, creating opportunities for potential hazards to surrounding devices and the environment. Nevertheless, few studies have examined the characteristics of LNG underwater leakage and subsequent vapor flame. The paper considers transportation safety and risk evaluation for LNG, with emphasis on accidental release and vapor flame. Introduction The cryogenic nature of LNG, with a boiling point of -162°C, raises safety concerns with regard to vaporization gas hazards and the potential for pool fires. According to the literature devoted to LNG accidental release and spill, three puncture positions have been proposed: Category I, where the leakage point is above the water line; Category II, where the point is at or close to the water line; and Category III, where the point is below the water line. A need exists to investigate LNG underwater leakage and combustion behavior for risk assessment. This work focuses on experimental research of the dynamic behavior of LNG jet release under water and the immediate burning on the water surface using three orifices and different crosswinds. The main points of investigation include the following: - Liquid-rising process and microbehavior in the orifice - Flame geometry on the water surface under crosswinds - Flame-temperature distribution on the water surface Experimental Setup Experimental Facilities. Experiments were conducted in a rectangular tank measuring 1000 mm long, 500 mm wide, and 500 mm high, which was placed in a wind tunnel. The nozzles have diameters of 1, 3, and 5 mm in the middle of the discharge pipe. An inline cryogenic flow-meter with a measuring range of 0.06 - 0.6 m3/h was used to regulate the volume flow rate with an accuracy of 1.5 %. The pressure measurements were performed by a pressure gauge with a range from 0 to 4 MPa placed on the end of the discharged pipeline. The LNG jets were re-leased vertically into the bulk water at a depth of 0.6 m. Images were recorded using a high-speed video camera system. Experimental Conditions. The window was closed when LNG was released, and the discharged gas was quickly diffused from the wind tunnel. The temperature in the room was 17±1°C and 14±0.5°C in water. The relative humidity was approximately 50%. All tests were conducted three times.