Constant Water Level Research Articles

Statistical analysis for biogeochemical processes in a sandy column with dynamic hydrologic regimes using spectral induced polarization (SIP) and self-potential (SP)

SUMMARYThe capillary fringe (CF) is characterized by transient and steep redox gradients and is thought to be a hot spot for biogeochemical processes. Understanding chemical fate and transport in the CF is significant, however, biogeochemical dynamics at the CF are poorly understood because of the difficulty to measure representatively with high spatio-temporal resolution at depths under dynamic hydrologic regimes. Hydrogeophysics is a developing field that uses minimally intrusive and quick response methods to monitor hydrological properties. Two geoelectrical methods [spectral induced polarization (SIP) and self-potential (SP)], which are sensitive to the solid–liquid interfaces (SIP) and biogeochemical processes (SP) can address the above difficulty. The challenge lies on linking the geoelectrical responses with biogeochemical processes, where many different processes contribute to the signals. We conducted a soil column experiment under five hydrologic regimes focusing on nitrogen transformations with SIP and SP measurements: (1) a static regime with a stable water level; (2) an infiltration regime with periodic pulse infiltration events with a constant water level and (3) fluctuating regimes with water level fluctuations under three drying-wetting frequencies (6/12/18-day-cycle). This is the first large lab-scale work in a well-controlled and highly instrumented soil column. The dynamic hydrologic conditions stimulated complex biogeochemical processes at the CF, and therefore the SIP and SP signals result from many physical and biogeochemical processes. Therefore, we relied on statistical analysis in this study for a novel interpretation. Spearman correlation analysis supported water content played the most important role in real conductivity (σ′) dynamics in the vadose zone, whereas fluid conductivity dominated σ′ in the saturated zone. Both correlation analysis and spatial moment analysis implicated that water content was the driving factor for both σ′ and imaginary conductivity (σ″). A multiple linear regression model indicated the gradient of redox potential, the gradient of soil matric potential and water content were the three main influencing factors for the SP signals. We proposed that the water level fluctuation can efficiently facilitate microbial electron transfer through ions transport between the different redox zones, and aggregate redox processes to create SP signal gradients. Depth zonation analysis, using six environmental indexes (Eh and nitrogen species; water content; real conductivity; imaginary conductivity; SP signal; microbial community composition), suggested that water content induced by soil hydrology was the most dominant factor, captured by all the indexes. In turn, it led to indirect inference on biogeochemical processes and resultant geoelectrical signals. Applying geoelectrical methods to such biogeochemical processes will not only lead to a better understanding of the mechanistic meanings of the geoelectrical signals, but also build relationships between geoelectrical signals and biogeochemical parameters to facilitate a novel way to monitor biogeochemical processes.

Determination of Irrigation Lengths in Vertisol Soils Using the Two-Point Infiltration Method and Kostiakov-Lewis Equation

Vertisol soils, which cover large lands in irrigated areas in Turkey and the world, swell when wet and form deep cracks when dry. These properties of Vertisol soils cause a significant decrease in irrigation efficiency when irrigating with surface irrigation methods, thus causing water insufficiency and drainage problems. If appropriate irrigation time, flow rate and furrow-border lengths are used, water application efficiency can be increased in these soils. For this purpose, two-point infiltration tests were carried out using 120 m long, 0.5-0.6% slopping furrows. A constant water level orifice was used to keep the flow rate unchanged during the tests. Water advanced and recession times were observed and recorded at stations created at 20 m intervals. Before and after the test, the cross-sectional area of the furrow was measured with a rill-meter. By evaluating the obtained data, the Kostiakov-Lewis infiltration equation, which is expressed as Z = 0.00822 τ 0.27695 + 0.00048 τ equation, was obtained. With the determined equation, the optimal irrigation length was estimated to be approximately 85 m for 90% water application efficiency and 115 m for 80% water application efficiency, using the advance and recession curves.

Real-Time Flood Monitoring with Computer Vision through Edge Computing-Based Internet of Things

Natural disasters such as severe flooding can cause catastrophic losses to properties and human lives. Constant real-time water level monitoring prior to a flooding event can minimise damages and casualties. Many of the currently deployed water level monitoring systems typically use a combination of float-type or ultrasonic sensing, image processing and computer vision techniques. However, these systems incur high computing and hardware requirements, which hinder the deployment of such systems in resource-constrained and low-cost environments. The recent development of technologies empowered by the Internet of things (IoT) and edge computing have enabled real-time systems to be deployed at a significantly lower cost and a far more distributed manner. In this paper, we propose an architecture for flood monitoring using RGB-D cameras with stereoscopic capabilities to measure the water level in an open environment. Our system uses image preprocessing techniques to account for chromatic aberration due to overexposure, followed by postprocessing before the depth readings are extracted. Data processing and water level information extraction are entirely performed on an edge computing device, therefore greatly reducing the amount of data transmitted to the cloud server. We practically implemented and experimentally validated this system in the real world, under a wide range of weather and lighting conditions. Our results showed promising outcomes and demonstrated the applicability of our proposed system in a wider context.

Localized carry‐over effects of pond drying on survival, growth, and pathogen defenses in amphibians

AbstractClimate change is increasing variability in precipitation patterns in many parts of the globe. Unpredictable changes in water availability can be particularly challenging for organisms that rely on precipitation‐fed water sources for completing their life cycle, such as many amphibian species. Although developmental plasticity can mitigate the impacts of changing environments for some species, this strategy can come at a cost to other fitness‐linked traits, such as immune function. We investigated localized variation in the capacity to respond to pond drying and evaluated whether developmental responses induced carry‐over effects in disease susceptibility in three leopard frog species (Rana [Lithobates] pipiens and Rana sphenocephala; two populations each, and one population of Rana chiricahuensis). Using mesocosms located near the site of collection (<15 km away) in five regions spanning a latitudinal gradient, we raised tadpoles under simulated fast drying, slow drying, or constant water levels. After metamorphosis, we characterized several aspects of the skin microbiome, immune function, and response to exposure to the fungal pathogen Batrachochytrium dendrobatidis (Bd). Note that for R. chiricahuensis, the only carry‐over effect measured was response to Bd exposure, for which we observed no effects of pond drying. We found that developmental plasticity in response to drying was rare, except in the southernmost population of R. sphenocephala. In this location, tadpoles responded by accelerating development, and frogs with shorter larval periods developed more severe infections following Bd exposure post‐metamorphosis, suggesting a trade‐off between surviving pond drying and pathogen defense investment. In the three other locations, a lack of accelerated metamorphosis in drying treatments was accompanied by increased mortality, decreased anti‐Bd function of the microbiome, and/or greater Bd infection after exposure. Overall, results suggest that faster drying conditions will likely have negative impacts on amphibians with long larval periods, both directly and indirectly via carry‐over effects. Because effects of drying exposure were not uniform within a species, our findings suggest that local responses may not be generalizable to other regions of the range. These multifaceted effects of climate change on pathogen defenses are increasingly relevant as emerging infectious diseases threaten global biodiversity.

Nonlinear stability and dynamic characteristics of hydropower station under fluctuation of downstream channel water level

This paper aims to investigate the hydropower station with downstream channel (HSDC) and reveal the effect of fluctuation from downstream channel on its stability and dynamic characteristics under load disturbance. Firstly, a novel mathematical model of HSDC considering the fluctuation of downstream channel water level is established. Then, the stability and dynamic characteristics of HSDC are analysed by Hopf bifurcation. Finally, it is revealed that the effect of the fluctuation from downstream channel water level on the stability and dynamic characteristics of hydropower station. The results indicate that the HSDC is a supercritical system, and the stable domain is on the lower left to the bifurcation line in K p -K i plane. Considering the fluctuation of downstream water level, the stable domain of HSDC is wider than the reference where downstream channel water level is constant. The fluctuation of downstream water level has two-sided effect on the dynamic characteristics of HSDC, which makes the attenuation rate lager but setting time longer. Moreover, the more obviously the downstream water level changes with flow, the stronger the influence on stability and dynamic characteristics of HSDC are. Therefore, it is safer to design hydropower station and select the parameters of governor according to constant water level in engineering.

Mathematical Modeling of Transient Water Interactions Between a Sloping Aquifer and an Adjusting Stream

Due to the constantly changing hydrological conditions of the surrounding water reservoirs, estimating water table changes in response to stream-stage variations and downward recharge is an emerging area in hydrology. Mathematical modeling is the emerging tool for predicting water table behavior in many complex geological situations. In this paper, a stream-aquifer model is considered and variations in the water table height have been calculated. At one end, the aquifer is in contact with a constant water level, and at the other end, the water level is rising exponentially from an adjoining stream. An analytical equation is solved by the Laplace Transform method for estimation of water table fluctuations in response to combined effects of bed slope and non-uniform recharge and seepage.

Wavelet Analysis of Dam Injection and Discharge in Three Gorges Dam and Reservoir with Precipitation and River Discharge

The Yangtze River has been the primary support of the resources and transportation of China. The Three Gorges Dam and Reservoir on the Yangtze River is one of the world’s largest dams. The influence caused by the dam and reservoir on the river system has been overwhelming and destructive. For better water resource use and flood-prevention planning, more understanding is needed regarding the dam’s impact on river discharge, regional precipitation, and frequency of extreme rainfall events. This study aims to analyze the changes in river discharge and regional precipitation records before and after the construction of the Three Gorges Dam. This research examines temporal correlations among these data by collecting daily dam injection and dam discharge records, the precipitation from ground stations, and river discharge. The time series are analyzed with the wavelet analysis. The precipitation datasets decrease in wavelet magnitude after 1998 when the dam was built in the wavelet analysis. The annual cycle, shown as a bright year line through the time range, still exists in the analysis result after 1998, but the magnitude of the annual cycle has reduced. The river discharge shows a decrease of wavelet magnitude at the three downstream locations. The possible explanation of this pattern could be the human-controlled dam discharge. The constant water level maintained in the reservoir by human control would slow down the flow speed and stabilize it.

Experimental study of bed morphology evolution under two-dimensional dam-break flow

The present study discusses the evolution of bed morphology under 2D dam-break flow by conducting a set of laboratory experiments. The experiments were conducted in a 1.6 m × 28 m × 1.0 m glass flume with non-uniform fly ash as the bed material. Two scenarios were designed: no inflow (scenario 1) and nearly constant water level (scenario 2) in the upstream reservoir. During the experiment, the water levels were measured by pressure sensors which were buried under the sediment layer, and the bed morphology was measured by an ultrasonic ranging system. The results showed that: (1) in scenario 1, the range and depth of the scour pit continued to increase, but the location of the deepest scour point did not change significantly; (2) in scenario 2, the depth and range of scour increased after the dam break, but the growth rate slowed down obviously after t = 15 min. The data can be employed to understand the bed morphology evolution under a dam-break flow, validate numerical approaches, and test geomorphic flood models.

Modeling reservoir surface temperatures for regional and global climate models: a multi-model study on the inflow and level variation effects

Abstract. The complexity of the state-of-the-art climate models requires high computational resources and imposes rather simplified parameterization of inland waters. The effect of lakes and reservoirs on the local and regional climate is commonly parameterized in regional or global climate modeling as a function of surface water temperature estimated by atmosphere-coupled one-dimensional lake models. The latter typically neglect one of the major transport mechanisms specific to artificial reservoirs: heat and mass advection due to inflows and outflows. Incorporation of these essentially two-dimensional processes into lake parameterizations requires a trade-off between computational efficiency and physical soundness, which is addressed in this study. We evaluated the performance of the two most used lake parameterization schemes and a machine-learning approach on high-resolution historical water temperature records from 24 reservoirs. Simulations were also performed at both variable and constant water level to explore the thermal structure differences between lakes and reservoirs. Our results highlight the need to include anthropogenic inflow and outflow controls in regional and global climate models. Our findings also highlight the efficiency of the machine-learning approach, which may overperform process-based physical models in both accuracy and computational requirements if applied to reservoirs with long-term observations available. Overall, results suggest that the combined use of process-based physical models and machine-learning models will considerably improve the modeling of air–lake heat and moisture fluxes. A relationship between mean water retention times and the importance of inflows and outflows is established: reservoirs with a retention time shorter than ∼ 100 d, if simulated without inflow and outflow effects, tend to exhibit a statistically significant deviation in the computed surface temperatures regardless of their morphological characteristics.

Naturalising a heavily modified urban river: Initial habitat evolution in the Manzanares River (Madrid, Spain)

AbstractBetween the 1910s and 1960s, the segment of the Manzanares River in the city of Madrid was channelized to allow for intensive urban development and a series of barrages were built to maintain constant water levels and create the aesthetic of a large deep river. As part of a renaturalisation strategy for the river by the Madrid City Council, the complete opening of the barrages' hydraulic gates in spring 2016 allowed for natural physical processes to occur that, in turn, facilitated colonisation of newly‐formed habitats by vegetation and fauna. The present study evaluates the initial effects of the barrage gate openings on instream habitats through the analysis of (i) geomorphological, physico‐chemical and vegetation metrics, and (ii) hydraulic variables associated with potential preferential conditions for native fish fauna, whose populations were greatly diminished. This approach incorporates an integrative view of the multivariate nature of the fluvial ecosystem. Results show a substantial reactivation of habitat heterogeneity over a short timeframe. In addition, newly‐emerging habitat conditions, related to sediment activation, improved water quality and diversified hydraulic conditions, are promoting potential preferential habitats for native fish fauna. This study can help aquatic researchers and administrators in understanding how an urban river can evolve with a cost‐effective intervention focused on the recovery of self‐forming dynamics. This application of process‐based river restoration strategies to a heavily modified river can also lead to the improvement of its ecological potential, as required by the European Union's Water Framework Directive.

Design procedures for a passive pyramid solar still with an automatic feed water system

Design procedures are presented here using conceptual design to optimize the performance of a passive pyramid solar still by introducing an automatic feed water system to compensate for the evaporated water from the tank. The procedures may be adopted for passive or active solar still systems. The water level is optimized to be fixed as it shall reduce due to continuous evaporation if no automatic method is used. That will improve the performance of the solar still and increase its output yield. The design procedures considered customer needs which are surveyed and products specifications are decided. Design targets are specified using the quality function deployment. Three design alternatives are proposed and compared, and the best alternative is chosen based on the decision matrix. An auxiliary tank was added between the storage tank and the solar still with a ball valve to maintain a constant water level inside the auxiliary tank and a screw jack to control the elevation of the auxiliary tank and water level. Based on the hydrostatic principle, the elevation of the water level inside the auxiliary tank and solar still must be the same. Therefore, controlling the elevation of the water level inside the auxiliary tank using the screw jack controls the water depth inside the solar still. The proposed feedwater system can maintain the water level inside the solar still to its optimum value that improves the solar still productivity and convenience for the end-user.

SLOPE STABILITY ASSESSMENT OF THE UPSTREAM SLOPE OF THE DRY MOUNTAIN FLOOD CONTROL RESERVOIR DURING THE FLOOD

The flood control is one of the priority goal for successful economic activity on the areas that are periodically suffer from floods. Such areas are the mountainous regions of the Ukrainian Carpathian Mountains. Floods on the mountain rivers are repeated several times each year, and are characterized by the sudden water level rise with almost the same rapid decrease of the water level. Active flood protection measures include dry mountain flood control reservoirs, the principle of which is to transform part of the flood runoff and to accumulate water for the short time in the the artificial reservoir, with followed rapid emptying to the minimum level. The complex hydraulic regime is formed in the body of the dam which forms the flood control reservoir during the flood, that is different from the operation of the water permanent reservoir. The design of the flood control structures is car-ried out in accordance with Ukrainian building codes for the construction of the water reservoirs with constant water level, and require testing the stability of the downstream slope for the maximum water levels under steady state seepage conditions and assessment the upstream slope stability during the water level decreasing from the maximum level calculated in the steady state condition, these calculations do not correspond to the real seepage processes in the body of the dam of the dry flood control reservoir. Therefore, the purpose of this work is to determine the necessary boundary conditions of the flood control reservoir operation and upstream slope stability assessment by the limit equilibrium method. In the article the operation of the dry mountain flood control reservoir was analysed and found that the dam was characterized by two states: dry reservoir with water minimum water level and variable position of the seepage curve in the core and the upstream prism during the flood. The main factors influencing the upstream slope stability are the physical and mechanical properties of the soil, the laying of the slope, the period of time when the high-water level is maintained and the intensity of water level dropping. The upstream slope stability was evaluated by the Morgenstern & Price and Ordinary methods on the Slope/w software package. After the first 25 hours of the flood (period of high-water levels and the next water level dropping) the Safety Factor evaluated by limit equilibrium methods began to decrease, and reached the minimum value during the greatest seepage curve gradients at the time between 45 and 50 hours. Slope stability calculations by the limit equilibrium method were compared with the results of calculations performed by the SRM method, the values ​​of the Safety Factor and the way of their change during the flood evaluated by Ordinary and SRM methods almost coincide, which indicates the reliability of the results obtained by different methods of slope stability analysis

1-Dimensional numerical modelling of unsaturated water flow and oxygen diffusion in overburden material column using hydrus 1-D

Coal mining activities, especially overburden material dumping can cause a negative impact into the environment, i.e., acid mine drainage, Acid mine drainage is characterized as low pH water with high sulphate and metal content produced from sulphidic-bearing overburden material with oxygen and water. In unsaturated condition, both of gaseous and water phases exist, acid mine drainage is generated. This study aims to characterize and model the water content in unsaturated condition and diffusion of oxygen of overburden material using the Hydrus 1-D software in a laboratory-scaled column. Laboratory-scaled column is initially filled with 75-cm height of dry overburden material and subjected into 5-cm constant head water level at the top of the column with free-flow condition at the bottom of column. The modelling result shows the water content of overburden material varies within depth and time elapsed and is saturated between 32400 minutes and 36000 minutes after initial wetting. Diffusivity of oxygen is linearly correlated with the water content of the overburden material at any given time and depth that varies between 1.34 × 10−7 m2/s and 8.80 × 10−12 m2/s. Water content and diffusivity of oxygen is expected to affect the generation of acid mine drainage in the overburden material.

Research on numerical simulation and intelligent computing of vehicle wading driving by smooth particle hydrodynamics method

The method based on Smooth Particle Hydrodynamics (SPH) is a meshless method which is widely used at present. Its advantage is that it can effectively improve the mesh distortion when finite element is used to deal with large deformation, and its particle characteristics are suitable to deal with the simulation problem of fluid. Based on the actual vehicle wading test site and the actual parameters of the vehicle, combined with the actual situation and theoretical basis, the SPH method is used for numerical simulation analysis of the vehicle wading problem. By comparing the simulation process with the actual water changes during wading, the feasibility of using SPH method in vehicle wading application is proved. In the simulation process of vehicle wading driving, under the condition of constant water level, by setting different wading speeds of vehicle, the flow law and change mechanism of water free surface are analyzed, which are of great significance in theoretical research and engineering application research.

Effects of Dynamical Change in Water Level on Local Scouring around Bridge Piers Based on In-Situ Experiments

To evaluate the stability of bridge piers affected by the local scouring, the existing formulas for estimating the maximum local scour depth have been developed based on the results of experiments conducted under a constant water level. However, the applicability of these formulas to the cases where the water level rises and falls, such as a water level change in a real river, is not clear. In this study, water flow experiments were conducted on cylindrical and oval bridge pier models to investigate the effect of iterated water level change on the progression of local scour around piers. Results of experiments with cylindrical and oval pier showed that the local scour depth and length increased by an iterated action of the water level change; however, these values converged after the number of iterated actions reached a certain time. The local scour length at upstream of the bridge pier was approximately 1.8 times larger than the theoretical value, which was calculated through the local scour depth and angle of repose in water. The local scour length is an important parameter for defining the streambed protection zone, which is one of the measures against local scour, and we showed that the streambed protection zone needs to be defined more widely.

Air Warming and Drainage Influences Soil Microarthropod Communities

The degradation of wetlands due to climate change is of critical concern to human beings worldwide. Little is known about the potential synergistic effects of simultaneous water level reduction and warming on the underground wetland ecosystems. We conducted a 5-month field experiment in the Sanjiang Plain, utilizing open-top chambers and water level automatic control systems to investigate such synergistic effects. Soil springtails (Collembola) and mites (Acari) in the top (0–20 cm) soil layers were sampled to calculate their density, diversity, and to screen for indicator species. Warming significantly influenced soil springtail communities, slightly increasing the total density and total abundance under the natural water level while reducing them under a constant water level. In addition, Anurida maritima and Vertagopus laricis, two indicators for the natural water level, had the highest densities in the natural water level treatment and under the combined treatment of warming and natural water level, respectively. Cheiroseius sinicus and Malaconothrus tardus had the highest densities in warming under the 0 cm water level, significantly higher than the other three treatments. This study also revealed the importance of maintaining fluctuating water levels for microarthropod communities influenced by global warming, providing a theoretical basis for water level control in wetland restoration.

Redox dynamics at a dynamic capillary fringe for nitrogen cycling in a sandy column

The capillary fringe (CF) is the last barrier for groundwater protection. Studies investigating the effects of cyclic groundwater fluctuation on nitrogen transformations, a critical biogenic element, in soil systems received less attention relative to near-surface and groundwater processes. We conducted an experiment in a highly instrumented 91-cm sandy soil column under five hydrologic regimes: (1) stagnant system with a static water level, (2) periodic pulsed infiltration with a constant water level, and (3) groundwater fluctuation under three frequencies (6/ 12/ 18-day-cycle). Under groundwater fluctuation regimes, the soil column can be divided into four zones: aerobic zone (10–30 cm), hypoxic zone (40–50 cm), anoxic zone (60–70 cm), and anaerobic zone (80–100 cm). The stable high Eh occurred in the aerobic and hypoxic zones, while the stable low Eh appeared in the anaerobic zone. The Eh at the upper anoxic zone (60 cm) appeared to show a strong cyclic pattern and the Eh at the lower anoxic zone (70 cm) gradually decreased until it reached values similar to the anaerobic zone. Nitrate overwhelmed other nitrogen species in the aerobic and hypoxic zones. The lower boundary of the nitrate-dominant zone was sensitive to the water level, which means that oxygen supply depends on the water level fluctuation. Ammonium dominated the anoxic and anaerobic zones, and the upper boundary of the high ammonium zone was constant, which implies that denitrification reached the maximum capacity in the anaerobic zone. The dominance of a single species in these zones suggests incomplete cycling of nitrogen. In contrast, nitrogen removal was enhanced with increasing frequency of groundwater fluctuation. Low total nitrogen concentration was observed at the hypoxic and anoxic zones boundary, due to the co-occurrence of nitrification and denitrification. The ratio of dissolved organic carbon to dissolved inorganic nitrogen can indicate the relative strength of nitrification–denitrification, subsequently distinguish the zonation of nitrogen status in this soil system. Additionally, ferrous sulfide particles accumulated at the anaerobic zone with intensified reducing condition, which deserves more attention. The observations presented in this study strengthen the understanding that the CF acts as a hot-spot and occasionally as a hot-moment, which is of great importance to chemical cycling, highlighting the role of groundwater fluctuation in mass transfer across the CF.

Spillway hydraulic performance assessments of the Belogorsk reservoir

The article presents the calculation of the hydraulic performance of the spillway structure of the Belogorsk reservoir, one of the largest freshwater bodies on the Crimean Peninsula. Due to its geographical location and natural features, Crimea has always been and remains one of the poorest regions of Russia with water resources and water delivery to the consumers is a priority. Hydraulic performance assessment of the spillway structure is carried out for two design cases: 1) with a variable upstream water level rate and a fully open gate with a = 1.00 m; 2) with a constant upstream water level (UWL) equals highest water level (HWL) and a variable value of the shutter opening. Based on the results of determining the hydraulic performance of the water intake structure, the maximum discharge flow rate (at the mark UWL equals HWL) was obtained, which was Q = 6.06 m3 / s, which is 1% higher than the design data of the throughput of the structure (Q = 6.00 m3 / s) and the total throughput of all spillway structures is Qtotal = 79.32 m3 / s, which differs from the design data by less than 1% and indicates the accuracy and reliability of the obtained data.

All you need is air—Alternating activated sludge system BIOCOS without electromechanical equipment

Exclusively air-driven operation is an essential feature of the cyclic activated sludge process BIOCOS. Switching the air-flow between diffusers, agitation, and recycle air-lift keeps operation and maintenance simple and leads to significant energy savings used for mechanical devices. The overall energy demand for the whole biological system with settling was found to be below 20kWh/PE.a. This hybrid technology shows a constant water level characteristic for continuous flow systems and time-based control. Modular rectangular tank configuration and high solids operation targets a compact footprint. Process wise, the settling sludge blanket in the two alternating settling tanks was found to contribute considerably to post-denitrification and enhances phosphorus removal. During the last years, approximately 200 BIOCOS plants have been implemented mainly in Germany, Austria, Spain, and China, some of the operational results are presented in this paper. PRACTITIONERS POINTS: BIOCOS is a hybrid process with alternating settling tanks at constant water level. The performance of demonstration plants shows high resilience against hydraulic and organic peak loads. The energy demand for the process was found to be very small. The process is driven with no electromechanical equipment but one main blower station. The sludge blanket in the alternating settler significantly contributes to denitrification and phosphorus removal.

Habitat diversity enriches waterbird community at Bolivar Wastewater Treatment Plant in South Australia

The wastewater treatment plant at Bolivar in South Australia contains three groups of ponds which provide different managed habitats. Ponds 1, 2 and 3 contain a constant level of water of >1 metre in depth throughout the year, whereas in Ponds 4, 5 and 6 the water level is reduced each year with the result that the ponds become largely dry for several weeks from late summer. The third group of eight ponds, the sludge lagoons, are anaerobic and each year two or three of these ponds gradually dry out. In this study, we compared the abundance of the various species of waterbirds on these three groups of ponds throughout the period from September 2021 until December 2023. We found major differences in abundance of birds between the three groups. Most of the waders, together with Black Swan Cygnus atratus, Hardhead Aythya australis and Eurasian Coot Fulica atra, were largely present on Ponds 4–6, whereas Blue-billed Duck Oxyura australis, dabbling ducks, and three species of cormorants (Phalacrocoracidae) tended to be more abundant on Ponds 1–3, with the sludge lagoons generally having mainly Grey Teal Anas gracilis.