Outgoing Water Research Articles

Estuarine Exchange Flow in the Salish Sea

AbstractThe Salish Sea is a large, fjordal estuarine system opening onto the northeast Pacific Ocean. It develops a strong estuarine exchange flow that draws in nutrients from the ocean and flushes the system on timescales of several months. It is difficult to apply existing dynamical theories of estuarine circulation there because of the extreme bathymetric complexity. A realistic numerical model of the system was manipulated to have stronger and weaker tides to explore the sensitivity of the exchange flow to tides. This sensitivity was explored over two timescales: annual means and the spring‐neap. Two theories for the estuarine exchange flow are: (a) “gravitational circulation” where exchange is driven by the baroclinic pressure gradient due to along‐channel salinity variation, and (b) “tidal pumping” where tidal advection combined with flow separation forces the exchange. Past observations suggested gravitational circulation was of leading importance in the Salish Sea. We find here that the exchange flow increases with stronger tides, particularly in annual averages, suggesting it is controlled by tidal pumping. However, the landward salt transport due to the exchange flow decreases with stronger tides because greater mixing decreases the salinity difference between incoming and outgoing water. These results may be characteristic of estuarine systems that have rough topography and strong tides.

”Increasing oil recovery by injecting an air composition of the surface active substance (SAS) in the irrigated layers”

The introduction of a water-gas mixture into the reservoir necessitates gas production along with oil in the field. This creates difficulties in the old fields of Azerbaijan. Therefore, unlike the water-gas mixture injected into the layers, the use of a solution of surfactant (SAS) in water instead of air water instead of gas guarantees that the process is both cheap and effective. During the injection of the mixture, the air, being a non-wet phase, will enter the small permeable pores of the layer, helping to displace the oil from it, as well as prevent the formation of water tongues in the layer. The solution from the SAS reagent to be added to the water will not only increase the oil-washing capacity, but also relieve the surface tension at the border with the oil, causing weakening of the capillary forces. Thus, the impact coverage of the reservoir will increase, which will ensure the rise of the oil recovery of the reservoir. By replacing the injection of water with the injection of a solution-air composition through an injector to remove residual oil from the irrigated reservoir, the oil yield coefficient increased by 27%. The injection of the solution-air composition through the reservoir injector increased the oil recovery and also led to a decrease in the volume of the outgoing water.

Mapping Urban Water Balance to support the integrated design of water cycles in the peri-urban areas

The paper tests the effectiveness of a methodology used to analyze the water element in the urban context, in supporting design choices oriented toward sustainable water management. In particular, it presents a mapping technique of the variables used for calculating the UWB (Urban Water Balance) using the open data available for Milan. The methodology is applied to a peri-urban area of the city’s southern outskirts, the Corvetto/Chiaravalle district. The availability of the data has allowed identifying the minimum spatial area on which to carry out a balance of water flows using open-source GIS in the census block (CB). The methodology’s effectiveness in supporting the design choices was verified on two specific census blocks, the first representing the diffuse residential built area, the second an existing farmhouse no longer productive with residential functions. The main design strategy’s goal was to reduce water withdrawal from the aqueduct and reuse part of the outgoing water to limit the discharge into the sewage system as much as possible.

Implications of fire-induced evapotranspiration shifts for recharge-runoff generation and vegetation conversion in the western United States

Wildfire has been shown to increase, decrease, or have no detectable effect on actual evapotranspiration (ETa) fluxes in the western United States. Where disturbance-induced shifts are significant, source-water hydrology may be impacted as ETa constitutes the largest outgoing water flux in much of the arid West. We conducted pixel-scale analysis of 30-m ETa data and various meteorologic and landscape variables at 13 burn scars to understand how wildfire disturbance impacted hillslope-to-burn scar-scale hydrology and vegetation conversion. Significant fire-induced ETa reductions (between approximately −15 to −50%) were detected at nine burn scars through the tenth post-fire year, while ETa recovery rate varied substantially by ecoregion and pre-fire vegetation type. Along elevation gradients, both climate and land disturbance influenced the location of runoff/recharge generation zones, and more net water was generated from a snow-dominated burn scar in dry post-fire years than in wet pre-fire years. However, especially in arid locations where ETa is water-limited, compensatory ETa pathways may be more likely to dampen fire effects on total basin water yield where intact vegetation is located between the disturbance footprint and the basin outlet. Relationships between post-fire ETa shifts and early-successional vegetation conversion were also tracked. The majority of burn scars with significant fire-induced ETa reductions experienced conversion patterns typical of the western United States following stand-replacing disturbance, with forests converting to shrub/scrub and/or grassland/herbaceous cover through at least the end of the study period (eight to 15 years depending on date of the fire event). This could have important implications for high-elevation, snow-dominated watersheds – some of the most critical source water areas - as previous research indicates that wildfire activity is moving upslope and into vegetation communities that have not evolved to withstand fire. Finally, we show that much of the Colorado River Basin’s high-yield source water areas are vulnerable to the fire-induced ETa reductions and vegetation conversion observed herein. As such, water managers in the Colorado River Basin can anticipate changes in burn scar hydrology and snowpack mechanics following fire disturbance.

Numerical assessment of a solar pond under transient state with realistic energy extraction from all possible zones

A solar pond from which thermal energy is extracted from its non-convective zone (NCZ), lower convective zone (LCZ) and the ground below is modelled in transient state. The novelty of the study lies in the fact that heat extraction in each of the three zones is considered to be realistic, taking into account temperature drop across the exchanger surfaces. The pertinent weather parameters are described by curve fitting as series of sinusoidal time functions. Using these expressions, implicit finite difference method is used to solve the five coupled partial differential equations involved in the analysis, and the scaled down model is validated with simpler models available in the literature. To quantify the practical utility of pond, the final outgoing water stream heated from the pond is fed to a large scale solar still to assess the usefulness in a desalination application. Annual distillate production of the still coupled to such a pond is calculated and its variation with various manually adjustable parameters is studied. A total of 9 such parameters have been investigated. It is observed that there are five pond parameters related to pond’s operation that possess optimum values that maximize annual distillate production. These are: NCZ and LCZ thicknesses, NCZ and LCZ exchanger pipes’ radii, and ground extraction mass flow rate. An increase in any of the remaining parameters: upper convective zone (UCZ) thickness, ground exchanger pipes’ radius and NCZ, LCZ extraction mass flow rates generate a decrease in distillate produced. It is also revealed that extraction should be carried from how many zones depends on the application coupled to the pond, and in this case, where the application is a solar still, LCZ with ground extraction turns out to be the best choice. Further, the assumption of ideal NCZ and ground extraction used in the literature is seen to overestimate system output by nearly 46%. Therefore, this model is a generalized one and various other single or dual zone extraction models available so far become subsets of it. This generalized model presented here can serve to design such a triple zone extraction based solar pond system in a realistic and practical manner and help evaluate suitable values of user-controlled variables that yield maximum output of the application to which the pond supplies energy.

Design and analysis of a novel solar compression-ejector cooling system with eco-friendly refrigerants using hybrid photovoltaic thermal (PVT) collector

• A novel solar cooling system is designed and analyzed. • The solar cooling efficiency increased by 33.1 %. • The COP of the refrigeration cycle is improved by 8.23 %. • R290 has the best performance in the system. World faces cold crunch and solar energy exploitation plays a vital role in facing this problem. This study aims at improving the performance of combined solar ejector vapor compression refrigeration cycles ( EVRC ) with two evaporators using a photovoltaic thermal ( PVT ) collector. The PVT collector supplies the system's required power, such as compressor and water circulator pump. The outgoing water is further used to cool the condenser and subcool the condenser outlet refrigerant to improve the system efficiency. This work also investigates the utilization of the environmentally friendly refrigerants of R1234yf, R600a, and R290 to reduce the global warming issue by replacing the typical R134a refrigerant. The results showed that the optimal water flow rate for the highest system efficiency and the lowest exergy destruction is 0.05 kg/s. With the passage of water (with optimal flow rate), the collector's electrical efficiency, total solar cooling efficiency, and refrigeration cycle performance coefficient ( COP ) can be increased by 11%, 33.1%, and 8.23%, respectively, compared to the non-cooling state. The R290 refrigerant also performs best in terms of maximum efficiency and lowest system exergy destruction, among other refrigerants, with COP and solar cooling efficiency of 3 and 0.52, respectively, which is 4.8% and 4.6% higher in comparison with the R134a.

Efficiency of the Integrated Nitrogen Removal Device to Remove Ammonia in a Hog House

It is crucial to explore new methods to deal with ammonia pollution in hog barns. In this experiment, ammonia gas generated from the decomposition of nitrogenous organic matter, such as feed and manure in hog barns, was studied. Growing environmental parameters monitored included temperature, humidity, and ammonia nitrogen concentration. For 92 days between March and May, ammonia emissions were characterized by monitoring and collecting the ammonia concentration during the selected time. The results showed that the average temperature in the hog house was 18.2 ± 2.7°C, the humidity was 62.7 ± 0.3%, and the average ammonia concentration range was 17.7∼23.1 mg m−3. The collected ammonia-nitrogen-containing wastewater that entered the denitrification device showed 173, 232, 201, and 280 mgNH4-N/L, respectively. An integrated denitrification device with anaerobic ammonia-oxidizing bacteria as a functional strain was used for denitrification treatment. Through the change of ion concentration in the incoming and outgoing water, an 85.5% average denitrification efficiency was calculated according to the denitrification reaction chemical formula. Thus, the results presented here provide data support for the future use of microbial denitrification equipment to treat ammonia in hog houses.

Mapping of physical-chemical, microbiological, and chemical component characteristics of water samples from Nile tilapia slaughterhouses

The aim of this study was to analyze the physicochemical and microbiological characteristics of the water used in fish processing and tilapia fillets in slaughterhouses. The study analyzed the processing water from nine slaughterhouses. The water samples for analysis were collected at three points: process water (PW), it is the water used inside the slaughterhouses in direct contact with the fish; clean water entering the purification tank (EPT) and water leaving the purification tank (LPT). The processing waters of the nine tilapia slaughterhouses were analyzed and characterized according to their microbiological and physical-chemical characteristics. The results of microbiological analyzes meet the values indicated by legislation, in most cases. Regarding microbiological data, we can highlight that there was an increase in the total coliforms of the water entering the purification tank to the water leaving the purification tank in five slaughterhouses. Still, there was an increase in the aerobic mesophilic bacteria content observed in the outgoing water in relation to the inlet water of the purification tank in seven slaughterhouses. In relation to the physical chemical analyzes for the process water samples, the results show that the evaluated indices are in accordance with the values indicated by the legislation. The levels of Cd, Mg, Sc and Cd were below that detectable by the analysis in all slaughterhouses. The levels of Al, Sc, As, Rb, Ba, Pb, Mn, As, Se, Rb, Ag, Sb, Ba and Pb were detected only in one or two slaughterhouses. It is concluded that although some abattoirs have water characteristics outside the limits indicated by the legislation, the observed changes were not significant and small adjustments are necessary for the adequacy.

Design of Solar Water Heater Using Collector Cylindric Parabolic and Coil Heater as Absorber at Focus Point

Solar thermal water heating systems have been developed to replace conventional heating. Therefore, the design of a parabolic cylinder collector-type solar heating unit with a coil-shaped heater (absorber) has been carried out. The cylindrical collector is made of an aluminum plate covered with a reflective sticker and the base is insulated, having a diameter, height, length, and position of the focal point 150, 60, 200, and 22.4 cm, respectively. The coil water heater of 3/8-inch diameter copper pipe having a diameter, pitch, and length of 20, 3, and 200 cm, respectively. The concentration ratio between collector area and heating pipe area (absorber) is 3.6. The results of heating trials conducted from 10:00 to 16:00 WIT, in Duplo to 100 liters of water circulated through the heating pipe at a speed of 0.017 kg/sec, indicate that heating is affected by fluctuations in radiation intensity. Thermal efficiency is inversely proportional to heating time. the lower the time when the difference between the temperature of the incoming and outgoing water gets smaller, or in other words in the evening the water temperature approaches a steady state. The achieved maximum water-heating temperature is 53C in the average radiation range during the test is 687-693 W/m2.

Mathematical Models of the Energy Characteristics of a Backpressure Steam Turbine Based on a Simulation Study

The backpressure steam turbine installations for combined production generate thermal energy and electricity. The produced electricity depends on the heat load determined by consumers. Heat energy is released in the district heating system through water, which is heated with the exhausted steam in boiler-condenser (district heater). The operation regime of the installation is influenced by load of the released district heat and the temperature of the district heat water at the input and output of the boiler-condenser. The variables are heat load of the district heating system and temperature of district heat water at power plant output. The temperature of the district heat water at the boiler-condenser input is an uncontrollable variable, whose value depends on heat consumption. It influences the steam pressure in the boiler-condenser and the available enthalpy drop of the cogeneration installation. In this report, a verified simulation model is applied on a backpressure steam turbine installation, type SST-300 CE2L/V36S. A multivariate simulation is carried out, studying the performance of the installation in off-design regimes. The results obtained are used for the creation of regression models of the installation’s energy characteristics. They reveal the dependence between the energy characteristics of the cogeneration steam turbine by the released heat load in the district heating system and the temperature of incoming and outgoing district heat water. The accuracy of the developed models is evaluated through multiple correlation coefficients. The mathematical models could be successfully used to optimize the operating regime of the backpressure steam turbine installation.

Investigation of Performance of Solar Flat and Curved Plate Collectors through Numerical Simulations

Solar energy is radiant light as a form of thermal heat energy which can be obtained and used by means of a variety of solar apparatus. As apparatus the flat and curved plate solar collector is specifically designed for assembling solar energy as a solar water heater system. The designing potency of this collector lone can generate medium level hot water from radiant sunlight source via absorbed plates. Standard type flat and curved plates solar collector plates are mostly used in remote coldest regions of the world where hot water is consumed for commercial and domestic purposes. These types of solar collector Plates can cheaply be manufactured compared to other solar panels like solar Shingles, Polycrystalline Solar Panels, Mono-crystalline Solar Panels, and Thin Film Solar Panels. For future work, this proposed pre-design is recommended for fabrication. A numerical study was carried-out on eight city locations in China by tracing their horizontal and vertical longitudinal, latitudinal lines noting the date, time and sunlight feeding of temperatures in the Celsius scale with the help of simulation and modeling tools like CFD, ANSYS FLUENT software, mesh geometry tools, and by using the Navier-Stokes and Continuity equations by fluid flow discharge rate, mass flow, water temperature and dropping of temperature, radiation working mechanisms, dimensions of water flowing tubes and absorber plates, density, the velocity of water as the working fluid, the viscosity of water in a cold and hot state as a process of Pre-design. Work also focuses on the comparison between flat plate collector and curved plate collector radiant sunlight absorption, As end result it is found the Curved plate collector produces 22% more elevated heat of outgoing water than flat plate collector.

Efficacy of water filters for dental chair units: assessment of the filtration action versus Coxsackievirus B5.

SummaryIntroductionThe microbiological safety and control of the water used in dental practice has a critical importance for avoiding cross-linked infections in the dental office. The aim of this study was to establish coxsackie virus filtration of the water applied to a dental unit.MethodsA specific water filter-system was used, to verify the viral load in the outgoing water. The statistical analysis was performedusing the Shapiro-Wilk and t-Student test.ResultsThe outcome of the evaluation of the virologic tests shows an excellent capability of virus filtration that attested 99.9999% in the volume analyzed. A statistical difference was found in the bacterial water contamination parameter before and after filtration. (P = 0.000000).ConclusionsAccording to the tests, medical devices applied to a dental unit are able to filter viruses and therefore reduce risk of contamination in the dental office.

Coarse-Grained Model of Underground Thermal Energy Storage Applied to Efficiency Optimization

Seasonal storage of thermal energy, by pumping heated water through a borehole array in the summer, and reversing the water flow to extract heat in the winter, can ameliorate some of the intermittency of renewable energy sources. Simulation can be a valuable tool in enhancing the efficiency of such storage systems. This paper develops a simple, efficient mathematical model of spatial temperature dynamics that focuses on the radial water flow in a cylindrical borehole array. The model calculates the time course of the temperature difference between outgoing and incoming water accurately, and allows new optimization strategies to be explored easily. A strategy based on discharging water heated by the array before it reaches the array center can increase the storage capacity by 25% for a system with a 20% smaller radius than the well-studied Drake Landing system. If the density of boreholes is also doubled, the improvement is 29%.

Pengaruh Tinggi Air Masuk Dan Diameter Pipa Outlet Terhadap Tinggi Air Keluar Pompa Hidram

The pump is a device that can lift water from a lower height to a higher place, but because there are many pumps in the market that use electricity as a power plant and the selling price is quite high for rural communities, an appropriate pump is needed and cheap. Hydram pump is one alternative, where the workings of this tool can raise the water to a higher place with energy or power that comes from the water itself. Making Hydram pumps itself is relatively inexpensive, simple and durable. Hydram pumps are very popular because they work without using energy, so it is suitable for use in villages that do not have electricity. The purpose of this study was to determine the effect of the height of the incoming water and the diameter of the outlet pipe on the height of the outlet water at the hydram pump. In this study the height of the incoming water was varied as high as 0.5m, 1m and 1.5m while the diameter of the aoutlaet pipe was varied by 0.5inc, ¾ inc and 1 inc. From this experiment it was found that the height of the incoming water and the diameter of the outlet pipe significantly influence the height of the outgoing water, of the two factors most influential on the height of the outgoing water is the height of the incoming water

Evaluation of the water quality Before and after the Al-Diwaniyah Textile Factory in Iraq

The study aimed to evaluate the quality of entering and leaving water to the textile factory in Diwaniyah and water of AL- Diwaniyah River for the period October 2017 to January 2018, Thirteen sites were selected (three sites) on AL-Diwaniyah River and (ten sites) within Al-Diwaniyah textile factory.The evaluation of water quality includes14 parameters as confirmed on spatial and temporal changes of these parameters in Thirteen sites (S1,S2,S3, S4,S5, S6,S7,S8,S9,S10,S11,S12 and S13).These Thirteen sites are divided into four groups, the first group (water of AL-Diwaniyah river), includes (site 1,site12 and site 13). The second group ((Water prepared for textile industries), includes (site 2 and site 3). The third group (industrial processing water), included (site 4, site 5 and site 6). The fourth group is the treatment unit (Outflow water) that includes (site 7, site 8, site 9, site 10, site 11 and site 12). site 1 (AL-Diwaniyah river water), site 2 (soft water), site 3 (boilers water), site 4 (Water for textile preparations), site 5 (completion water), site 6 (water of printing and dyeing), site 7 (water of primary collection basin), Site 8 (Waters of the sedimentation Basin), site 9 (chemical treatment water), Site 10 (Biological Treatment Ventilated Water), Site 11 (water of Filters), site 12(Final assembly basin (river basin) and site 13 (AL-Diwaniyah river water after distance from the dumping of textile industrial waste). the study includes physical tests, which include Electrical Conductivity (EC), Total Dissolved Solids(TDS), and conducting chemical tests that included pH, Total Hardness (T.H), Calcium (Ca), Magnesium (Mg), Total Alkalinity (T.A), Chlorides(Cl), Sulphates (SO4), Phosphates (PO4) and Nitrates (NO3), as well as heavy metals Chromium (Cr), Nickel (Ni) and Cobalt (Co), For 13 sites inside and outside AL- Diwaniyah textile factory and AL- Diwaniyah River.The results of physical and chemical analysis show the following means of: Electrical Conductivity (2277.75 μs /cm in site 13 to 3991.75 μs /cm in site 11)., Total Dissolved solids TDS (759.75 mg / l in site 2 to 1790.75 mg / l in site 11)., pH (7.94 at site 2 to 9.29 at site 4), Total Hardness (313.25 mg / L at site 1 to 574mg / L at site 9), Calcium (166.25 mg / L at site 1 to 375 mg / L at site 9), Magnesium (21.23 mg / L at site 11 to 70.63 mg / L at site 8), Total Alkalinity (288.75 mg/ l at site 5 to 596.25 mg/ L at site 10), Chlorides (174.75 mg / L at site 2 to 483.5 mg / L at site 4), Sulphate (363 mg / L at site 2 to 521.75 mg / L at site 1). Phosphate (0.29 μg/l at site 3 to 1.315 μg /l at site 6)., Nitrate (21.6 μg /l at site 3 to 37.05 μg /l at site 11) The highest mean of Cr, Ni and Co were (0.145, 0.1745, 0.043 mg / L) at site 9 and the lowest mean of Cr, Ni and Co were (0.00125, 0,061475 mg / L) at site 2 and 13, respectively but CO were (N.D) at site1, 2 and 3.The water quality index values of the water inside and outgoing water from AL- Diwaniyah textile factory generally ranged from (fair to marginal). where the sites located on AL- Diwaniya River (group 1), the site 1 and site 13 got on (fair) were (69.20,67.93), respectively while site 12 got on (marginal) was (51.41)., While sites within the factory (group 2,3 and 4) from (site 2 to site 12) lowest value was (47.82) at site 4 and the highest value was (64.47) at site 2 so the water quality in these sites were (marginal).

Bathymetric survey of lakes Maninjau and Diatas (West Sumatra), and lake Kerinci (Jambi)

Determining the bathymetry of lakes is important to assess the potential and the vulnerability of this valuable resource. The dilution and circulation of nutrients or pollutants is largely dependant on the volume of water and the incoming and outgoing fluxes, while the degree and frequency of mixing depends on the water depth. The bathymetry of lakes is also important to understand the spatial distribution of sediments, which in turn are valuable archives of natural hazards and environmental change. We thus conducted a bathymetric survey of lakes Maninjau and Diatas in West Sumatra and lake Kerinci in Jambi (Indonesia) using a sonar. We found maximum water depths of 168 m, 55 m, and 105 m and minimum volumes of 9.79 km3, 0.32 km3, and 1.57 km3 for lakes Maninjau, Diatas and Kerinci respectively. Although lake Maninjau is the largest, it is vulnerable due to the low water fluxes in and out of it, and is thus currently threatened by increasing levels of cultural eutrophication. Lake Diatas is smaller but surrounded by less human settlements and is thus less impacted by related human activities. Lake Kerinci is relatively voluminous, has larger incoming and outgoing water fluxes, and doesn’t appear to be suffering greatly from surrounding human activities. Given the sizes and inlets of these lakes, Maninjau and Diatas likely have the highest potential for hosting a long-term sediment record built from low sedimentation rates.

New insights into the apple fruit dehydration process at the cellular scale by 3D continuum modeling

An accurate understanding of the dehydration kinetics of biological materials is essential to optimize their dehydration processes and to produce high-quality dried products. For a soft, cellular material like fruit, the underlying mass transport and deformation mechanisms at the cellular scale play a key role here. To improve our insight into the cellular scale dehydration kinetics, a 3D model is developed to quantify the impact of the changes in the cellular structure of apple (parenchyma) cells during dehydration on the tissue sorption isotherm and water permeability. As a step beyond the current state-of-the-art models, the model incorporates the changes in the cellular structure over entire dehydration process, starting from a turgid cell down to the occurrence of (free) shrinkage, plasmolysis (detachment of the cell membrane from the cell wall) or lysis (rupture of the cell membrane). Regarding the tissue sorption isotherm, plasmolysis induced a reduction in the equilibrium water content (up to 60%) compared to the free-shrinkage or lysis cases at the same water activity level. On the other hand, the tissue water permeability was found to increase up to five times when lysis occurs, compared to free shrinkage or plasmolysis. A parametric study also quantified the dependency of tissue permeability on the cell wall thickness, the cell membrane permeability, the cell size and the elongation aspect ratio of the cell. We identified that the dehydrated, shrunken cellular tissue reduces the outgoing water flux compared to fresh tissue for the same water potential gradient. As such, dehydrated tissue forms a barrier against further moisture removal from the fresh tissue below.

ANALISIS PERBANDINGAN UNJUK KERJA PEMANAS AIR TENAGA SURYA TIPE PLAT DATAR DENGAN SISTEM SINGLE DAN DOUBLE CUTOFF

Abstract: Warm water is needed by human being to take a bath, wash their clothes, their dishes etc. By the photothermal conversion, the solar energy can be used to heat the water. Flat solar collector is a tool which is used to capture energy of the sun radiation then convert it into heat to heat up water in collector’s pipes. The number of glass cover used effects the performance and efficiency of the collector. From this research, it is found that the efficiency of the collector is better when the cover used are two glasses than one glasses. The temperature difference of incoming and outgoing water in the collector using two glasses 15 ̊C higher than that of one glass.

Water pollution in wastewater treatment plants: An efficiency analysis with undesirable output

The environmental efficiency of 96 Tuscan (Italian) wastewater treatment plants (WWTPs) is investigated taking into account the quality of the outgoing water in terms of pollutant. In this regard, the presence of the residual nitrogen in the outgoing treated water is considered as undesirable output. The efficiency analysis is performed by applying a novel integrated Analytic Hierarchy Process/Non-radial Directional Distance Function (AHP/NDDF) approach, combining the benefits of the two techniques. Similarly to the standard NDDF approach, the suggested model allows to include simultaneously inputs, desirable and undesirable outputs and not to overestimate the efficiency scores. At the same time, the AHP inclusion gives the possibility to directly take into account the decision maker preferences in the weighting system and to encompass some existing directional distance function models as special cases.The obtained results are then used to identify the efficiency explanatory variables: among them, the facilities’ capacity, the percentage of wastewater discharged by the industrial and agricultural activities and the level of compliance with the pollutant concentration threshold set by the legislator have a significant impact on the WWTP performance. The integrated performance assessment allows the water authorities to combine the WWTP efficiency together with the environmental sustainability issue and it has the potential for further promising environmental inspections.

Simultaneous photocatalytic and microbial degradation of dye-containing wastewater by a novel g-C3N4-P25/photosynthetic bacteria composite.

Azo dyes are very resistant to light-induced fading and biodegradation. Existing advanced oxidative pre-treatment methods based on the generation of non-selective radicals cannot efficiently remove these dyes from wastewater streams, and post-treatment oxidative dye removal is problematic because it may leave many byproducts with unknown toxicity profiles in the outgoing water, or cause expensive complete mineralization. These problems could potentially be overcome by combining photocatalysis and biodegradation. A novel visible-light-responsive hybrid dye removal agent featuring both photocatalysts (g-C3N4-P25) and photosynthetic bacteria encapsulated in calcium alginate beads was prepared by self-assembly. This system achieved a removal efficiency of 94% for the dye reactive brilliant red X-3b and also reduced the COD of synthetic wastewater samples by 84.7%, successfully decolorized synthetic dye-contaminated wastewater and reduced its COD, demonstrating the advantages of combining photocatalysis and biocatalysis for wastewater purification. The composite apparently degrades X-3b by initially converting the dye into aniline and phenol derivatives whose aryl moieties are then attacked by free radicals to form alkyl derivatives, preventing the accumulation of aromatic hydrocarbons that might suppress microbial activity. These alkyl intermediates are finally degraded by the photosynthetic bacteria.