Simultaneous Denitrification and Nitrification in the Lab-scale Oxidation Ditch with Low C/N Ratio

AbstractIn this study optimal operational parameters for carbon and nitrogen removal (specifically dissolved oxygen concentrations in different zones, hydraulic retention time and flow velocity) for wastewater typical for the Moscow region (low C/N and C/M ratio) in the Oxidation Ditch have been determined. The processes of nitrification and carbon oxidation in the studied system were stable. The possibility of simultaneous denitri-nitrification in the Lab-scale Oxidation Ditch with Low C/N ratio has been proved. The results of this study will be used in further researches

Research for waste water treatment technology with low production of excessive active sludge

The article reflects the possibility to create a technological scheme of waste water treatment of domestic and similar type of sewage within minimal amount of excessive active sludge by means of bioreactors with immobilized feed. There are various aspects to be considered: technical, economic, social and ecological. According to the above it is strongly needed to provide a combination of proper waste water treatment, minimal sludge formation and the possibility for a further use of the sludge. One of the ways to achieve the goal above is to use an immobilized feed in the aeration tank. The necessary experiments were carried out in the department of waste water treatment and water ecology. The article includes the scheme of the facility and other parameters of the experiments, which has been carried. The combination of aerobic and anaerobic processes helps to provide proper quality of integrated biological treatment. Chambers of the aeration reactor were also equipped with the polymer feed of various structures. The sludge treatment that was also strongly needed was made by means of aerobic stabilization with the use of ejecting aeration. The results of experiment showed a good effect in both components – sewage and sludge treatment. Afterwards there was also an industrial model launched which confirmed the results of the previous stage

Evaluating drivers of spatiotemporal variability in individual condition of a bottom-associated marine fish, Atlantic cod (Gadus morhua)

An organism's body condition describes its mass given its length and is often positively associated with fitness. The condition of Atlantic cod (Gadus morhua) in the Baltic Sea has declined dramatically since the early 1990s, possibly due to increased competition for food and hypoxia. However, the effects of biotic and abiotic variables on body condition have not been evaluated at local scales, which is important given spatial heterogeneity. We evaluate changes in distribution, experienced environmental conditions, and individual-level condition of cod in relation to covariates at different spatial scales using geostatistical models with spatial and spatiotemporal random effects. Sprat, Saduria entomon, temperature and oxygen were positively associated with condition, and depth was negatively associated. However, the effects of explanatory variables were small-spatial and spatiotemporal latent variables explained 5.7 times more variation than all covariates together (year excluded). Weighting environmental oxygen with local biomass densities revealed steeper declining trends compared to the unweighted oxygen in the environment, while the effect of weighting was less clear for condition. Understanding the drivers of spatiotemporal variation in body condition is critical for predicting responses to environmental change and to effective fishery management; yet low explanatory power of covariates on individual condition constitutes a major challenge

The settling behaviour of an activated sludge with simultaneous nitrification and dentrification

Sedimentation properties of activated sludge from the bioreactor with simultaneous nitrification and denitrification are studied in this paper. MLSS was about 2 g/l in the bioreactor, F/M ratio less than 0.4 gCOD/(gMLSSd), average dissolved oxygen concentrations were 0.35–0.75 mg/l. Latin square design method was used in this experiment. The results show that biomass at SND is characterized by high settling velocity. Sludge settling velocity function for this biomass was obtained

Energy efficient process of nitrification and denitrification in activated sludge system with low organic load

The article summarizes the results of the second phase of a comprehensive study of energy efficient wastewater treatment processes in oxidation ditches. Dependence of the efficiency of simultaneous nitrification and denitrification at the change of oxygen regime have been determined at the second phase of the study. Results of the phase confirm the fundamental possibility of the withdrawal of biomass in energy-efficient mode with high quality of wastewater treatment

Laboratory Measurements to Image Endobenthos and Bioturbation with a High-Frequency 3D Seismic Lander

The presented 3D seismic system operates three transducers (130 kHz) from a stationary lander and allows non-destructive imaging of small-scale objects within the top decimeters of silty sediments, covering a surface area of 0.2 m2. In laboratory experiments, samples such as shells, stones, and gummy worms of varied sizes (down to approx. 1 cm diameter) could be located in the 3D seismic cube to a depth of more than 20 cm and differentiated by a reflected amplitude intensity and spatial orientation. In addition, simulated bioturbation structures could be imaged. In a practical application, the system allows to determine the abundance of endobenthos and its dynamic in muddy deposits in-situ and thus identify the intensity of local bioturbation

Cathodoluminescence of carbon-related defects in hexagonal boron nitride

Hexagonal boron nitride is a wide band gap semiconductor exhibiting various luminescence bands in visible and near ultraviolet range, which can be used as single photon source. The luminescence band with zero phonon line at 4.1 eV is commonly ascribed to the carbon impurity introduced during crystal growth. In this paper we provide experimental evidence that carbon-related luminescent centers can be introduced in hBN by local electron irradiation in the chamber of scanning electron microscope at room temperature that can be used as a technique for the nanofabrication of single photon source devices with desired pattern

Using biogas as an energy source

This article discusses the topic of sewage sludge digestion. Anaerobic digestion of sewage sludge makes it possible to obtain biogas, which can later be used to generate heat or electricity. this approach to resource use is recognized worldwide as more environmentally friendly. The article discusses the experience of European countries in the production and use of biogas. In the Russian Federation, the situation is complicated by the fact that wastewater contains a small amount of organic matter, which is a product for biogas production. Therefore, methods have been proposed for increasing the content of organic matter in sediments, for example, by means of separate waste collection and disposal of organic waste through grinders into the sewerage system. Or, the amount of organic matter in the sewage sludge can be increased by adding manure from animal farms. The stages of sediment fermentation are considered. The topic of rationality and payback of the use of biogas is raised. Projects already working in different countries are being considered. Possible volumes of gas production and methods of air purification during sludge treatment are considered

Seasonal change of multifrequency backscatter in three Baltic Sea habitats

This study investigated the seasonality of acoustic backscatter intensities, exploring three habitats in the southwestern Baltic Sea: 1) a mussel-covered reef, 2) coarse sand and gravel, and 3) seagrass meadows. Backscatter information of different, partly calibrated frequencies (200, 400, 550, and 700 kHz) was collected in three seasons (May, August, and October). The acoustic data were supported by point samples and video profiles for grain size and benthic community analysis. Angular response curves helped to quantify the seasonal backscatter response of the different frequencies. The multifrequency and multiseasonal backscatter maps distinguish the three habitats and reveal variable seasonal differences in acoustic backscatter, but not all changes in the benthic community can be recognized in the acoustic data. 1) The high-backscatter response of the mussel-covered reef shows little seasonal differences and was frequency independent. 2) The ecologically valuable coarse sand and gravel areas show small-scale seasonal alterations in the sediment composition and morphology, mainly caused by changes in local hydrodynamics. Higher frequencies were found best suited to identify coarse sand and gravel. 3) Seagrass meadows seasonality is dominated by growth of seagrass blades, increasing the backscatter response compared to bare sand. The use of multiple frequencies is beneficial as the low frequency is sensitive to changes in the shallow subsurface and benthic features such as seagrass rhizomes, while the higher frequency highlights changes related to coarser sediment