Optimization of Process Parameters for Enhanced Degradation of Methylene Blue by Trough Ultrasonic

Due to the complex quality and the large discharge of printing and dyeing wastewater, it will pollute the environment and affect human health. Therefore, how to use efficient and inexpensive treatment methods to treat printing and dyeing wastewater has become an urgent problem to be solved. At present, most printing and dyeing wastewater contains methylene blue pollutants. Based on the previous research in this article, the process conditions for the enhanced degradation of methylene blue by trough ultrasound are optimized. Orthogonal test results show that the optimal process parameter for the degradation of methylene blue by trough ultrasonic is pH 12.70, and the initial With a concentration of 10.00mg/L and an ultrasonic power of 200W, under the above optimal process conditions, the degradation rate of methylene blue is 77.95%; Ultrasound improves the rapid degradation of methylene blue through mechanisms such as cavitation, thermal and mechanical effects. This process can be used for the industrial degradation of methylene blue. The application provides a research basis.

Spatio-temporal variations of water sources and mixing spots in a riparian zone

Riparian zones are known to modulate water quality in stream-corridors. They can act as buffers for groundwater borne solutes before they enter the stream at harmful, high concentrations, or facilitate solute turnover and attenuation in zones where stream water (SW) and groundwater (GW) mix. This natural attenuation capacity is strongly controlled by the dynamic exchange of water and solutes between the stream and the adjoining aquifer, creating potential for mixing-dependent reactions to take place. Here, we couple a previously calibrated transient and fully-integrated 3D surface-subsurface, numerical flow model with a Hydraulic Mixing Cell (HMC) method to map the source composition of water along a reach of the 4th-order Selke stream and track its spatio-temporal evolution. This allows us to define zones in the aquifer with similar fractions of surface- and groundwater per aquifer volume (called “mixing hot-spots”), which have a high potential to facilitate mixing-dependent reactions and in turn enhance solute turnover. We further evaluated the HMC results against hydrochemical monitoring data. Our results show that on average about 50 % of the water in the aquifer consists of infiltrating SW. Within about 200 m around the stream the aquifer is almost entirely made up of infiltrated SW with nearly no other water sources mixed in. On average, about 9 % of the aquifer volume could be characterized as “mixing hot-spots”, but this percentage could rise to values nearly 1.5 times higher following large discharge events. Moreover, event intensity (magnitude of peak flow) was found to be more important for the increase of mixing than event duration. Our modelling results further suggest that discharge events more significantly increase mixing potential at greater distances from the stream. In contrast near the stream, the rapid increase of SW influx shifts the ratio between the water fractions to SW, reducing the potential for mixing and the associated reactions. With this easy-to-transfer framework we seek to show the applicability of the HMC method as a complementary approach for the identification of mixing hot-spots in stream corridors, while showing the spatio-temporal controls of the SW-GW mixing process and the implications for riparian biogeochemistry and mixing-dependent turnover processes.

Sediment load determines the shape of rivers

Understanding how rivers adjust to the sediment load they carry is critical to predicting the evolution of landscapes. Presently, however, no physically based model reliably captures the dependence of basic river properties, such as its shape or slope, on the discharge of sediment, even in the simple case of laboratory rivers. Here, we show how the balance between fluid stress and gravity acting on the sediment grains, along with cross-stream diffusion of sediment, determines the shape and sediment flux profile of laminar laboratory rivers that carry sediment as bedload. Using this model, which reliably reproduces the experiments without any tuning, we confirm the hypothesis, originally proposed by Parker [G. Parker, J. Fluid Mech. 89, 127–146 (1978)], that rivers are restricted to exist close to the threshold of sediment motion (within about 20%). This limit is set by the fluid–sediment interaction and is independent of the water and sediment load carried by the river. Thus, as the total sediment discharge increases, the intensity of sediment flux (sediment discharge per unit width) in a river saturates, and the river can transport more sediment only by widening. In this large discharge regime, the cross-stream diffusion of momentum in the flow permits sediment transport. Conversely, in the weak transport regime, the transported sediment concentrates around the river center without significantly altering the river shape. If this theory holds for natural rivers, the aspect ratio of a river could become a proxy for sediment discharge—a quantity notoriously difficult to measure in the field.

Effect of Discharge on Hatching and Growth of Age-0 Black Bass in Two Southeastern U.S. Rivers

We examined the influence of variable discharge on hatching and age-0 growth for fluvial specialist and habitat generalist species of black bass Micropterus spp. in two southeastern U.S. rivers, the Flint River, Georgia (unregulated), and the Tallapoosa River, Alabama (regulated by several hydropower dams). Between 2008 and 2010, we collected 285 Largemouth Bass M. salmoides (generalist) and 254 Shoal Bass M. cataractae (specialist) from two reaches of the Flint River. In 2010–2011, we collected 309 Alabama Bass M. henshalli (generalist) and 216 Redeye Bass M. coosae (specialist) from two regulated reaches and one unregulated reach of the Tallapoosa River. Successful hatching of black bass in both rivers generally occurred from late March to early June when water levels were low and stable. Hatching distributions of all black bass were generally unimodal with little evidence of spawning disruption, except for Alabama Bass in the most-regulated reach of the Tallapoosa River, which appeared to be disrupted by large discharge events. Mean growth of both species in the Flint River varied from 0.64 to 0.82 mm/d across reaches and years; Shoal Bass generally grew faster than Largemouth Bass in all reach–year combinations. Largemouth Bass growth was inversely correlated to discharge variation in one reach, but Shoal Bass growth was not correlated to discharge variation in either reach. Alabama Bass and Redeye Bass growth rates in the Tallapoosa River were similar to rates observed for congeners in the Flint River; Alabama Bass grew faster than Redeye Bass. Growth of both species was inversely related to discharge variation in five of six reach–species combinations; the only exception was for Redeye Bass in the less-regulated reach. Results from this study suggest that variable discharge has less influence on successful reproduction of black bass than was reported for other fishes, but growth may be more affected by discharges resulting from anthropogenic sources than those associated with the natural regime.

Investigation of saltwater intrusion in thach han river system by mike hydro river package

Saltwater intrusion is one of the most severe problems for worldwide coastal regions, leading to negative impacts on both human and aquatic inhabitant communities. Quang Tri province, located in the Central Coast region of Vietnam, faces consequences of saltwater intrusion because of its dense river network and El Nino phenomena’s influences. To analyse hydrological, hydraulic processes as well as investigate saltwater intrusion’s situation in this province, the authors adopted MIKE HYDRO River package and obtained results with good agreements with measured data from survey campaigns. The present conditions scenario shows that saltwater intrudes Thach Han and Cam Lo rivers with a distance of 25.35 km and 15.04 km respectively, where the salt concentration is under 0.75‰ and water can be drunk and irrigated. The large discharge of 30 m3/s can only push saltwater only 1.85 km to the sea, which is insignificant in comparison with the value of seawater wedge length, saltwater intrusion in Thach Han river system can only be mitigated slightly. Since the authors only consider hydrological droughts, future scenarios in 2030 and 2050 have slight differences with the present, where topography and river flow remain unchanged. Based on the above results, non-structural measurements are not recommended to deal with saltwater intrusion for both present and future scenarios, and local authorities should consider structural solutions, e.g. constructions of anti-salt dams, during the decision-making process.

Study of the effects of check dam construction on the Limau Manih river using GIS

The problem of flooding or flash floods in watersheds often occurs, both in large rivers and small rivers. The frequency of occurrence varies greatly depending on the local climate. As a result of flooding, it causes more erosion and collapse of riverbanks and washes away all kinds of materials, such as wood, sand, and stone. Sometimes it also submerges rice fields, villages, and houses downstream of the river. Likewise, in the study location of the Limau Manih river, there has been a flood with a large discharge. It was recorded twice a year, namely in July and September 2012. One of the ways to reduce energy, scour, and avalanches on riverbanks is by building a check dam or weir. A check dam is expected to reduce the energy that arises due to differences in elevation or slope of the river channel. But on the other hand, the weir will raise the water level, so that the puddle becomes wider. Therefore, it is necessary to study the impact of weir construction on the extent of inundation. The study was conducted using ArcGIS to map inundation and HEC-RAS to simulate water levels along the river. Simulations were carried out for several return periods of rainfall events. The results of the study show that the planned flood discharge in the river of Limau Manih watershed is quite large. Meanwhile, from the simulation results, the inundation area is not too significant with the increase in the return period and the planned flood discharge. Although the simulation of the weir without widening the upstream part of the weir shows a significant increase in inundation area. This is most likely due to the weir in the upstream area of the river which is rather steep, so that water flows quickly through the overflow of the weir. However, the water level in the weir is higher than without the weir, as a result, water jumps and erosion occur downstream of the weir. For this reason, it is very necessary to monitor the scour behavior in the weir and the sedimentation rate, because this area has the potential to be eroded.

PENGARUH KRIB TERHADAP KECEPATAN ALIRAN PADA SUNGAI KRUENG ACEH

Krueng Aceh River is one of the rivers that has a large discharge crossing two administrative regions, namely Banda Aceh City and Aceh Besar District. One of the problems in Krueng Aceh river, precisely around the area of Pango fly over towards the downstream area is the high flow speed distribution at the turn of the river. The impact of the bridge pillar on the river turn results in changes in the cross section of the river endangering the public facilities in front of it. Based on this analysis, it is necessary to control and secure the river, namely by placing the Groyne. The purpose of this study is to obtain a speed distribution that occurs from placing Groyne construction. The methodology used in this study with hydrodynamic numerical modeling approach is by using the Surface Water Modeling System program (SMS 11.2). Calibrating with the parameter n = 0.025 has obtained an absolute error value of 0.039 in cross 1 and 0.051 in cross 2. Based on the analysis of 20 scenarios with 7 m and 9 m distance variations, 5-unit and 3-unit Groyne variations, and the variations in perpendicular angle and 10°, 30° (degrees) towards the downstream and the upstream area, as well as the flow speed with the same number of Groyne and distance variations, the result shows that (V7 m V9 m à 5 unit) and (V7 m V9 m à 3 unit). The simulation results show that the more the number of Groyne there are, the more negative the impact on the downstream area becomes, the more narrow the Groyne, the higher the flow speed value increases. From the 20 scenarios, we obtained a Groyne scenario that is in accordance with the field conditions, namely the Groyne scenario with a distance of 7 m, 3-unit cribs, and a Groyne placement angle of 30° towards upstream area (GUb3L7). The result of the velocity distribution observation shows that the scenario of GUb3L7 Existing (without pillars)

Statistical Modeling of Bilge Water Discharge from Ships During Normal Operation

This study estimated the amount of bilge water spilled from ships during normal operation and identified the contributing factors of the discharge by building a statistical model. To build the statistical model, we collected as much information as possible about the amount of bilge water in ships, then used the collected information to formulate a probability distribution of the discharge amount according to Bayesian statistics, and determined the parameters included in the model by applying a Markov Chain Monte Carlo method. The analysis of those parameters shows that the integrated bilge treatment system (IBTS) primarily contributes to reductions in the discharge amount, and that the container-type ship is involved with especially large discharge amounts.