Recirculation System Research Articles

Microbiological contamination of lettuce (Lactuca sativa) reared with tilapia in aquaponic systems and use of bacillus strains as probiotics to prevent diseases: A systematic review.

Aquaponic systems are food production systems that combine aquaculture and hydroponic in a closed recirculation system where water provides nutrients to plants while plants purify water for fish. In this system, tilapia is the most commonly cultured fish and can be easily integrated with vegetable cultivation. However, tilapia host a diverse microbiota some of which are pathogenic and can infect humans. Previous studies have reported contamination of lettuce by pathogenic bacteria which can cause human diseases. Thus, there is an urgent need to employ effective methods to control those bacteria, and Bacillus strains have been successfully used in this context. This systematic review aimed to provide a comprehensive overview of lettuce contamination by pathogenic bacteria and the use of Bacillus as probiotics to prevent diseases in aquaponics systems. This systematic review was performed using Preferred Reporting Items for Systematic Review and Meta-Analysis Statement (PRISMA) Guidelines. A total of 1,239 articles were retrieved and based on eligibility criteria, six articles were included after screening. The review revealed that Enterobacteriaceae, Coliforms, and Shiga Toxin-producing E. coli are the predominant bacteria contaminating lettuce leaves in Aquaponic systems, and Shiga Toxin-Producing E. coli can internalize in the lettuce leaves, putting public health at risk. The included studies did not report the presence of V. cholerae in lettuce grown in aquaponic systems, and the use of Bacillus as probiotics to control Escherichia coli and Vibrio Cholerae. Further research is needed to explore the potential of tilapia to act as a source of pathogenic bacteria that can contaminate lettuce, as well as to investigate the effectiveness of Bacillus strains as probiotics to control these bacteria and ensure food safety.

The protein transition—environmental footprints of farmed fish, microalgae and chicken for food, a case study in Kenya

AbstractChallenges of land scarcity, climate change and water shortage are contributing to escalating the shortage of protein rich food in sub-Saharan Africa. In Kenya a total of 27.8% of the population was undernourished, and a total of 72.3% were categorised as moderately or severe food insecure in 2021–2022. The need to investigate alternative protein sources with less impacts on land, water and climate change, which potentially could replace, at least some of the current production of livestock as the main protein source, is getting increasingly urgent. The main aim of this study is therefore to conduct an environmental footprint analysis of favourable protein production systems in Kenya to evaluate environmental impacts on land, water, and climate. The methodological approach used in this study is referred to as environmental footprint analysis, which is applied to assess; (1) farmed fish in ponds, (2) farmed fish in solar based affordable recirculation aquaculture systems (A-RAS), (3) dried spirulina (Arthrospira Platensis), and (4) chicken from semi-intensive farms. The results show that the most promising alternatives to cattle production are dried spirulina produced in ponds, followed by fish produced in affordable recirculation systems (A-RAS) run on solar energy. Spirulina fully replacing beef production would reduce water usage with 34.7 billion m3/year, land/water surface area with 34.8 thousand km2/year, and GHG emission with 28.2 megaton CO2eq/year. For fish farmed in A-RAS, such replacement would reduce water, land and emissions with 30.7 billion m3/year, 32.0 thousand km2/ year and 23.0 megaton CO2eq/year, respectively. This study illustrates that it is possible to tackle urgent challenges of food and nutrition security for millions of people in sub-Saharan Africa and worldwide with a sustainable protein transition towards a more sustainable, inclusive production system of small-scale farmers, if making use of alternative protein sources, such as from solar based A-RAS and microalgae.

Energy Efficiency and Mathematical Modeling of Shrimp Pond Oxygenation: A Multiple Regression Experimental Study

Aquaculture is one of the key economic activities to reduce food shortages worldwide. Water recirculation systems using pumps are crucial to maintain oxygenation and water quality, consuming about 35% of the total energy in this economic activity. This research proposes a multiple linear regression mathematical model to optimize oxygenation systems in intensive shrimp aquaculture by reducing energy consumption and minimizing water changes in ponds. The proposed model is key to optimizing the operation of pumping systems, allowing us to significantly reduce water turnover without compromising dissolved oxygen levels as a function of key variables such as water turnover volume, biomass, solar radiation (0–1200 W/m2), water temperature (20 °C–32 °C), phytoplankton levels (0–1,000,000 cells/ml), zooplankton (0–500,000 cells/ml), and wind speed (0–15 m/s). These variables are integrated into the model, managing to explain 94.02% of the variation in dissolved oxygen, with an R2 of 92.9%, which adjusts the system conditions in real time, reducing the impact of environmental fluctuations on water quality. This leads to an estimated annual energy savings of 106,397.5 kWh, with a total consumption of 663.8 MWh. The research contributes to the development of a mathematical approach that not only improves oxygenation prediction, but also minimizes the use of water resources, improving the sustainability and profitability of shrimp farming systems, and is a robust tool that maximizes operational efficiency in intensive aquaculture, particularly where water and energy management are critical.

Length-weight relationship and condition factor of Nile tilapia (Oreochromis niloticus) fed diets supplemented with guava and star gooseberry leaf extract

Background Nile tilapia (Oreochromis niloticus) is predominant cultured species in aquaculture. However, there is a scarcity of literature regarding relationship between guava and star gooseberry leaf extract and the condition factor. Thus, the present study aims to investigate the effect of guava and star gooseberry leaf extract-supplemented diets on the specific growth rate, length-weight relationship, and condition factor of Nile tilapia. Methods Six hundred and thirty Nile tilapia (8.7±0.4 g) were randomly distributed among twenty-one tanks (30 fish per tank) within a recirculation system. Over a 60-day period, the fish were fed diets supplemented with 5g/Kg and 10g/Kg of guava leaf extract (GLE-5, GLE-10), star gooseberry leaf extract (SGLE-5, SGLE-10), and a mixture of both (MxLE-5, MXLE-10). Subsequently, specific growth rate, length-weight relationship, and condition factor were determined. Results After 60 days, the specific growth rate was significantly higher in all the GLE, SGLE, and MxLE groups compared to the control group. The final lengths and weights differed significantly both in the control group and all the GLE, SGLE, and MxLE groups. The analysis of the regression equation indicated a positive correlation (r = 0.970, 0.977, 0.976, 0.974, 0.974, 0.974, and 0.969) between the length and weight of Nile tilapia in the control group and in all the GLE, SGLE, and MxLE groups. The regression exponent “b” values in all the GLE, SGLE, and MxLE groups were >3, indicating a positive allometric growth pattern in Nile tilapia compared to the control (b=2.866), which exhibited a negative allometry. The final condition factor values did not differ significantly in either the control group or any of the plant extract groups. Conclusions Nile tilapia exhibited positive allometric growth patterns and maintained good health when fed with GLE, SGLE, and MxLE groups. Therefore, these plant extracts demonstrate suitability for commercial Nile tilapia production.

Solar and Wind Energy Feasibility for a Water Treatment and Recirculation System Intended for Carniculture: Comparative Study Between the Cities Of Monteiro and Sousa – Paraíba – Brazil

Objective: This article presents a comparative study of renewable solar and wind energy production capacity between Monteiro and Sousa cities, located in the semi-arid region of Paraíba state, Brazil, to analyze the feasibility of using solar panels and/or wind turbines for energy supply in a water recirculation and treatment model applied to carciniculture. Method: A hypothetical-deductive method was employed and a bibliographic character was adopted in the research, taking as basis technical-scientific work information. Additionally, the research also presents quantitative theory, since it makes use of quantifiable results presented from measurable data that need to be properly expressed. A composite system was proposed, initially consisting of six identical units exposed in Figure 1, disposed under a roof, over which photovoltaic plates are placed for the supply of electrical energy to the hydraulic pumps contained in the system. The modeling study was based on wind speed and solar irradiance data in the cities of Monteiro and Sousa, with coordinates latitude -37.1214299 and longitude -7.8983769, and latitude -38.2285597 and longitude -6.7671611. These information were extracted from the Terraclimate database, using scripts written in Java and Python languages for extraction and processing. To predict wind power energy, the average wind speed in meters per second was used for each month, from January 1st, 2010 to December 31st, 2020. For modeling of photovoltaic power prediction, the average short-wave irradiance (W/m²) per month was considered, during the same period. To establish the monthly mean temperature, the average temperatures in Celsius were considered for the period from January 1st, 2010 to December 31st, 2020. For verification of the sufficiency of wind and photovoltaic systems for energy production maintenance, the energy demand of the System of Carciniculture was compared with the energy production by each of the sources considered, and based on the analysis made, it was defined which is the best energy production systemto be used and the best city where the defined system will be installed. Results and conclusions: The results show that the use of solar energy is economical, reduces social impacts generating employment and elevates environmental awareness, and has low environmental impact. The study found that solar energy generation capacity is sufficient and most suitable to keep the shrimp farming system running throughout the year, with observed variations between 226.8 kWh/month and 299.7 kWh/month in Souza city, and between 232.2 kWh/month and 369.0 kWh/month in Monteiro city, quantities more than enough for energy supply of the shrimp culture system, which presents a demand of 207.4 kWh/month. Implications of the research: The study points out that renewable energy can be an alternative more economical than other methods of energy generation, which could be a positive response to environmental and economic problems affecting the northeastern region, especially along the São Francisco River transposition, where Monteiro and Souza cities are among the last to receive it. Originality/Value: The use of solar energy is a viable solution for providing energy to shrimp culture. Additionally, the study also points out that this method may be more economical than other methods of energy generation.

Anaerobic biodegradation of real pharmaceutical-grade lactose manufacturing wastewater in a modified Internal Circulation Reactor

Pharmaceutical-grade lactose (PL) manufacturing generates wastewater containing high concentrations of biodegradable organic matter. In the absence of a suitable alternative, industries handle such concentrated streams by completely evaporating the entire stream and disposing of water-soluble solid residue in a landfill. Such a process is energy-intensive, and nothing useful is recovered from the stream. This study demonstrates the efficient and sustainable anaerobic biodegradation of real PL wastewater using a lab-scale internal circulation reactor (ICR) combined with an external recirculation system. The effects of feed Chemical Oxygen Demand (COD) concentration, organic loading rate (OLR), and hydraulic retention time (HRT) on COD removal efficiency, methane production, and the volatile fatty acids/alkalinity (VFA/ALK) ratio were evaluated. Under the highest feed COD concentration of 60,000mg/L, OLR of 4.5kg/m³∙d, and HRT of 13.33 days, the system achieved an average COD removal efficiency of 93.8% with methane production of 25.2L/d (specific methane generation of 0.32L/g CODremoved). By increasing the up-flow velocity from 0.044m/h (without external recirculation) to 1.5m/h (with external recirculation), COD removal improved from 63.6% to 93.4%, and methane production increased from 7.5L/d to 14L/d. The kinetics of COD removal fitted well in the modified Stover-Kincannon model (R2 = 0.99). A unique finding of this study is that the loose anaerobic sludge became granulated after 120 days, with 50% of the granules having diameters ≥ 2.0mm. The results of this study establish anaerobic biodegradation as a suitable treatment option for PL wastewater, thereby achieving UNSDG 6 (Clean Water and Sanitation) and 7 (Affordable and Clean Energy).

Performance Evaluation of Hydroponic Grow-Outs in An Innovative Coldwater Aquaponic System Featuring Rainbow Trout and Lettuce

A 45-day trial was carried out to assess the production performance of different hydroponic media in a novel do-it-yourself (DIY) low-tech re-circulating aquaponic system for temperate regions with rainbow trout (Oncorhynchus mykiss) and lettuce (Lactuca sativa). Rainbow trout juveniles (average weight of 35.59 g) were stocked in the experimental units at 2.8 kg.m-3 and fed with commercial floating pelleted feed at 8 % of their body weight in three treatments and a control. The lettuce saplings were randomly planted in the river stone bed (T1), crushed stone bed (T2), raft/deep water culture (DWC) unit (T3) and control (C) soil bed (fortified with NPK fertiliser) with equivalent planting intervals of 42 saplings.m-2. The system, designed with low-tech simplicity, was managed without alkalinity correction and depended entirely on plant growth and metabolism for biofiltration. The water quality parameters such as temperature, pH, dissolved oxygen (DO), dissolved free CO2, hardness, total alkalinity, ammonium, nitrite, and nitrate varied significantly (P < 0.05) among the treatments compared to the control. The final individual weight, biomass gain, specific growth rate (SGR), and feed conversion ratio (FCR) of rainbow trout were significantly better (P < 0.05) in media beds (crushed stone and river stone) compared to control and DWC systems. The final mean weights of rainbow trout in river stone (12.33 ± 0.002 g and crushed stone (12.39 ± 0.054 g) treatments were significantly higher (P < 0.05) than in DWC (12.1 ± 0.023 g) and control (12.09 ± 0.002 g) treatments. The production of lettuce was significantly greater (P < 0.05) in all three treatments (river stone: 4.33 ± 0.123 g, crushed stone: 4.53 ± 0.09 g and DWC: 4.31 ± 0.163 g) compared to the control (3.31 ± 0.172 g). The DWC including the media bed systems facilitates the improved performance of lettuce saplings in terms of final height and leaf number. These results show that a low-tech media bed system without a supplementary biofiltration unit can achieve sustainable production of both fish and vegetables in temperate hilly terrains.

Experimental study on current density distribution characteristics in a novel oxygen recirculation system of dead-ended proton exchange membrane fuel cell

ABSTRACT Dead-ended proton exchange membrane fuel cells (PEMFCs) using pure hydrogen and oxygen can improve fuel efficiency and cell performance, making them widely applicable in enclosed spaces. However, dead-ended PEMFCs are prone to flooding, which reduces cell performance and service life. To address this issue, an oxygen recirculation system utilizing oscillating flow generated by pressure differences is designed in this study. This system not only achieves close to 100% fuel utilization but also optimizes water management and enhances current density uniformity. The optimal oxygen cycling conditions were selected based on current density uniformity and cell performance enhancement. The results show that a larger pressure difference amplitude improves water removal from the cell; however, excessively large pressure differences can lead to unstable cell operation. The oscillating flow generated by pressure differences significantly improved current density uniformity, particularly at higher output load currents. Current density uniformity improved by 16.29% at a current of 75 A. The experiment demonstrates that the best current density uniformity is achieved when managing water using a pressure difference at 4-minute intervals, as longer or shorter oscillation intervals are unsuitable for dead-ended performance.

Reducing real driving fuel consumption and emissions with a hydraulic hybrid vehicle

We have successfully prototyped and tested the real-driving performance of a hydraulic hybrid heavy commercial vehicle. Hydraulic hybrid driveline technology was fitted to a Euro IV diesel truck equipped with a diesel particulate diffuser/filter and an exhaust gas recirculation system. An AVL portable emissions measurement system was fitted to the test vehicle to quantify gaseous and particle phase emissions species and an on-board diagnostic scan tool was used to obtain data from the trucks electronic control unit. Fuel consumption savings up to 17 % were accomplished in hydraulic hybrid mode when testing on a short urban driving route featuring a high intensity of stop-start activity. Average reductions in solid particle number concentration of 40 % were achieved along with increases in NOx, Hydrocarbons (THCs) and CO. Future work could target improved control system integration of the various driveline components to further reduce fuel consumption and emissions in an improved prototype design.

A novel strategy for enhancing high solid anaerobic digestion of fecal slag and food waste using percolate recirculation and dosage of nano zero-valent iron

To speed up reaching UN Sustainable Development Goal 6 for safe sanitation by 2030, integrating high-solid anaerobic digestion (HSAD) into decentralized systems could recycle fecal slag (FS) and food waste (FW), aiding a circular economy and toilet revolution. In this study, a percolate recirculation system and conductive material were used to improve mass transfer, stability, and enhance methane production in HSAD of FS and FW. This setup consists of a percolate tank and a digester tank, where nano-zero valent iron (nZVI) was dosed in the percolate tank (PnZVI in P) and the digester tank (PnZVI in D) and compared with a control with no additive (PControl). The highest cumulative methane yield of 519.43 mL/gVS was achieved in PnZVI in D, which was 4.52 and 3.59 times higher than that of PControl (144.59 mL/gVS) and PnZVI in P (114.96 mL/gVS). This finding demonstrates that the dosing strategy of PnZVI in D facilitated effective interaction among organic matter, microbial communities, and nZVI, resulting in organics removal efficiencies of 67.42 % (total solid) and 77.22 % (volatile solid). Moreover, microbial community analysis supported the efficacy of the PnZVI in D strategy, revealing the enrichment of Clostridium sensu stricto 1 (46.91 %), which potentially engaged in interspecies electron transport (Interspecies hydrogen transfer (IHT) and direct interspecies electron transfer (DIET)) with Methanobacterium (81.19 %) and Methanosarcina (17.11 %). These interactions contribute to enhanced methane yield and stability maintenance in the HSAD system with percolate recirculation. The findings of this study demonstrate that the implementation of HSAD of FS and FW, coupled with percolate recirculation and the addition of nZVI, holds promise for enabling sustainable sanitation practices in developing regions. Moreover, this approach not only facilitates resource recovery but also eliminates the requirement for water.

Growth of Oncorhynchus mykiss (Rainbow Trout) through a Recirculation System in the Foothills of the Extreme North of Chile.

Given the overexploitation of fisheries and the growing consumption of sea products, aquaculture is emerging as an alternative to meet the demand for protein at regional, national, and global levels. In northern Chile, the foothills of the Andes offer an opportunity for sustainable economic diversification. In this study, results of a rainbow trout (Oncorhynchus mykiss) culture in a recirculation system are presented, analyzing its growth and performance under altitude conditions. The research was carried out in Copaquilla, a small area in the foothills of northern Chile, 3000 m above sea level. Five thousand 15 g juvenile trout were acquired and transported by land from the Rio Blanco fish farm, successfully traveling more than 2100 km. During the 20-month-long culture, several growth parameters were evaluated, including specific growth rate, percentage of weight growth, feed conversion factor, survival, and Fulton's condition factor. All these parameters were within the normal growth range for trout, evidencing good-quality growth of the organisms. The results offer evidence that rainbow trout farming at 3000 m above sea level is viable and presents a viable performance, opening new opportunities for aquaculture in northern Chile.

Struktur Komunitas Fitoplankton pada Budidaya Ikan Koi (Cyprinus Rubrosfuscus) dalam Sistem Vertiqua Menggunakan Biofikal Filter Atas

Vertiqua biofical top filter is a cultivation technique with a recirculation system that utilizes limited land. Vertiqua is a solution for cultivation. When cultivating koi fish in vertiqua, the feed capacity increases and there is a high nutrient load so that the waters are easily polluted, therefore the presence of an upper biophysical filter can reduce pollution. This is important to study, especially the structure of the phytoplankton community because it is one of the biological indicators of ponds in koi fish cultivation. This research was carried out for 6 weeks in Sindangpalay Ciberem Sukabumi. The research was carried out by taking phytoplankton in the vertiqua at intervals of once every 2 weeks. The data analysis in this research is abundance, diversity, uniformity and dominance. During the research results obtained were abundance 636-673, diversity 2.6, uniformity 0.9, and dominance 0.01. The water quality studied was ammonia, nitrate, nitrite, phosphate, pH, DO, turbidity and temperature. These waters are stable and healthy, which is a positive indicator to support fish farming activities. The water quality in Vertiqua is classified as good and the ecosystem is balanced, these waters are ideal for supporting the productivity and health of farmed fish.

Permissible Extrapolation Justification of the Multiplicative Multifactorial Model and Its Application to the White Soot Production Technology

The solution to a specific technological problem is combined with the methodological development of a nonlinear multifactorial relationship to justify the boundaries of its extrapolation beyond the experimental range used. White soot was produced through two-stage carbonization of a silicate solution (composition, g/l: Na2O = 126.5, SiO2 = 107.7, Al2O3 = 3.1), obtained after processing waste tailings with carbon dioxide in a recirculation system. The influence of the deposition duration, temperature, and final pH value of the pulp on the formation of the specific surface area (Ssp, m2/g) of white soot was studied. The specific surface area was calculated from the average diameter of the white soot particles measured using an electron microscope. A multifactorial experiment was designed, and the experimental results were processed using a probabilistic deterministic method for experiment design (PDED) to obtain a nonlinear multiplicative combined model. A new interpretation of the subordination of the nonlinear multiple correlation coefficient R and the R2 value was given as relating to the structural and adaptive components of complex self-organizing systems. This determines their use for assessing the ratio of the basic R and extrapolated R2ranges of variation for each factor and any combinations thereof and multifactorial dependence in general. The results are presented in the form of multifactor tabular nomograms measured by the number of multifactor cells in localized areas of optimal sets that allow isolation by one or another combination of factors. The technological object of extrapolation of the ‘white soot’ production is linked to the solution of emerging methodological problems and illustrates the accessibility of the engineering application of the proposed method for combining nonlinear and linear approaches to mathematical experimental design. Doi: 10.28991/HIJ-2024-05-03-08 Full Text: PDF

Efficient natural gas combustion and NOx reduction: A novel application of simultaneous over-fire air (OFA) and flue gas recirculation (FGR) in a 250 MW opposed firing steam power plant boiler

OFAGR, as a new controllable technology, combines over-fire air (OFA) and flue gas recirculation (FGR) systems for modifying combustion characteristics and enhancing boiler efficiency. It also reduces NOx generation considerably. The effects of OFA and FGR on the combustion are reported for coal-fired boilers, however, no reference was found for the application of OFAGR, especially in boilers with natural gas fuel so far. Furthermore, the method of adjusting the ratio of OFA and FGR in OFAGR nozzles to achieve the required combustion modification is not investigated and this fact should be even covered for different types of boilers. For analysis of complicated combustive mixed fuel (natural gas) and air in furnace, computational fluid dynamics (CFD) simulated the flow by the use of Eddy-Dissipation Concept (EDC) and developing reactions by Jones-Lindstedt mechanism. Simulation results are validated by the measured boiler operation data for a 250 MW steam power plant boiler. The staged combustion in each burner is modeled by considering three inlet air flows (primary, secondary, and tertiary) with swirl. The effects of different ratios of OFA and FGR streams on characteristics of combustion and NOx production are investigated. The combustion efficiency, temperature profile, distribution of species, and the transferred heat flux to water-walls are computed, and analyzed. Results showed injecting only OFA from OFAGR nozzles, reduced NOx generation up to 55.4 % but lowered the furnace efficiency from 95.3 % to 93.1 %. When the OFAGR stream contained 25 % FGR and 75 % OFA (case study 2), an ideal state existed for increasing the combustion efficiency from 95.3 % to 96.0 % and NOx reduction by 58 %. Increasing the share of FGR in the OFAGR stream by more than 25 % improved the NOx reduction but reduced the combustion efficiency from 95.3 % due to the drop in the usable absorption heat of the boiler. Calculations showed that the OFAGR injection stream containing 64.1 % OFA and 35.9 % FGR reduced NOx formation from 274 to 112 ppm without losing furnace efficiency.

Integration Assessment of Renewable Energy Sources (RESs) and Hydrogen Technologies in Fish Farms: A Techno-Economical Model Dispatch for an Estonian Fish Farm

A fundamental aspect of fish farms is their energy consumption, which is essential for various activities like water supply, pool aeration, thermal conditioning, lighting, filtration, and recirculation systems. Due to volatile prices and rising energy use, costs have surged, requiring energy-optimization solutions for economic viability and pollution reduction. In this context, this study aims to evaluate renewable energy integration in these installations based on real data, assessing current operations, proposing renewable energy optimization, and exploring hydrogen systems for energy needs, using HOMER PRO® to analyze different scenarios. For this purpose, it targets a rainbow trout farm in Estonia, and by simulating the various hybrid configurations proposed, it aims to optimize its energy production and storage, ensuring feasibility and technical integration. The results of the simulations primarily demonstrate the potential for using the byproduct of electrolysis to cover the oxygen demand in these types of processes, reducing the demand for raw materials. Additionally, it is observed that storage enhances performance in isolated systems; however, the economically viable integration of hydrogen technology requires three assumptions: a regulatory framework allowing surplus energy sales to the grid, an existing infrastructure for hydrogen trading, and high energy purchase prices.

Parameter optimisation of marine four-stroke engine EGR systems using RSM and NSGA-III

ABSTRACT To reduce NOx emission of marine engines, an engine parameter optimisation method combining response surface method (RSM), Bayesian neural network and non-dominated sequence genetic algorithm (NSGA-III) is proposed. First, a simulation model of a marine four-stroke engine with an external exhaust gas recirculation (EGR) system was established and validated in AVL-BOOST software. Then, the five parameters of EGR valve opening, ignition advance angle, compression ratio (CR), intake valve opening (IVO) and exhaust valve closing (EVC) are selected as the decision parameters, and the three parameters of engine power, brake specific fuel consumption (BSFC) and NOx emission are taken as the target parameters to be optimised. In Design-Expert software, the response surface model is established by using the experimental design approach of central composite design (CCD), and the impact of decision parameters on target parameters are discussed by using response surface analysis. NSGA-III was used for the multi-objective optimisation of parameters, and the accuracy of NSGA-III was improved by the Bayesian neural network. The optimal solution is selected and verified by the technique for order of preference by similarity to the ideal solution (TOPSIS) approach. The results show that when the EGR valve opening is 47.5%, ignition advance angle is −18.99°CA, CR is 14.995, IVO is 15.27°CA and EVC is 7.68°CA, compared with the standard setting, the optimised power is increased by 4.17%, BSFC is reduced by 4.27%, and NOx emissions are reduced by 12.37%. Therefore, the combination of the Bayesian neural network and NSGA-III multi-objective optimisation can improve engine performance while reducing fuel consumption and NOx emissions.

Mitigating the Accumulation of Mercury (Hg) and Lead (Pb) through Humic Acid Application under Aquaponic Conditions Using Watercress (Nasturtium officinale R. Br.) as a Model Plant.

In aquaponic farming, there is a potential risk that heavy metals will contaminate the water, which can lead to heavy metal accumulation in the plants. Our research investigated the accumulation of mercury (Hg) and lead (Pb) under aquaponic conditions and the effect of their increased presence on the uptake of other macro- and micronutrients using watercress (Nasturtium officinale) as a model plant. The potential modifying effect of humic acid on heavy metal accumulation was also investigated. Adding Hg and Pb increased the mercury and lead levels of the watercress plants to over 300 µg kg-1, while the addition of humic acid significantly reduced the concentration of both mercury and lead in the plants compared to plants treated with heavy metals alone, from 310.647 µg kg-1 to 196.320 µg kg-1 for Hg and from 313.962 µg kg-1 to 203.508 µg kg-1 for Pb. For Fe and Mn, higher values were obtained for the Hg + humic acid treatments (188.13 mg kg-1 and 6423.92 µg kg-1, respectively) and for the Pb + humic acid treatments (198.26 mg kg-1 and 6454.31 µg kg-1, respectively). Conversely, the Na, K, Cu levels were lower compared to those in plants treated with heavy metals alone. Our results demonstrated that watercress can accumulate mercury, leading to high levels, even above food safety standards, highlighting the importance of water quality control in aquaponic systems. Furthermore, these results suggest that watercress could be used as a natural filter in recirculation systems. The addition of humic acid significantly reduced the accumulation of heavy metals and altered the element content in the plant.

Comparison of fish biological indicators of Clarias gariepinus hybrids grown in ras and pond farming conditions

To improve technologies in the field of commercial cultivation of aquaculture objects and further development of the warm-water aquaculture sector in Russia, we previously undertook breeding methods and approaches to obtain high-quality planting material for a promising commercial object — the African catfish Clarias gariepinus. This article presents, in a comparative aspect, the experience of growing hybrid offspring of African catfish, obtained from crossing two breeds — Mikhailovskaya and Tamanskaya, in a closed water supply system and in a pond farm in the Astrakhan region in the summer. It was shown that hybrid individuals of clariid catfish bred in a pond farm during the feeding period under consideration (from July to September) were characterized by a high specific growth rate and low feed ratio compared to hybrids grown in a recirculation system, respectively, 11.4% versus 9.87% and 0.96 versus 1. Also, based on the results of fishing, over two months of cultivation in a pond farm, hybrids of clariid catfish increased the total biomass by 13 times, while in a recirculating system it increased by 15 times, but the final biomass of fish turned out to be greater when reared in open reservoir (46.875 versus 10.87 kg). It was shown that the final individual mass of hybrid fish cultured in pond conditions was 11.0% higher than the final mass of individuals in the recirculation system. The conducted studies showed that in the climatic conditions of the Astrakhan region (VI fish-breeding zone), a promising direction for aquaculture of African catfish is the feeding cultivation of hybrid juveniles in pond farms. It should be taken into account that in order to obtain marketable fish products (i.e. individuals weighing over 1000 g), it is necessary to use fish seeding material with an average weight of at least 100 g.

Recuperation systems for fluorinated gases at the CERN LHC Experiments

Particle detectors at the LHC experiments are very often characterised by large detector volumes and by the need of using very specific gases, some of which are greenhouse gases (GHGs). Given their high Global Warming Potential (GWP) and the increasingly stringent European regulations regarding the use and trade of these gases, CERN is today strongly committed to reduce GHGs emissions from particle detector operation. Different approaches have been adopted for reducing the GHG emissions. To achieve this objective, the CERN Gas Team has developed gas recuperation plants: i.e. systems designed to extract GHGs from the exhaust of gas recirculation systems allowing further re-use and, therefore, reducing drastically GHGs emissions without changing detectors operation conditions. They are industrial-scale systems, each of which relies on different principles for gas separation and purification. Considering the unique gas mixtures used in particle detectors, these recuperation systems have been specifically developed as no industrial apparatus currently exists to address these requirements. Recent developments are concerning plants for recuperation of CF4, C2H2F4 (also called R134a), SF6 and C4F10, which are used respectively for Cathode Strip Chambers, (CSCs) Resistive Plate Chambers (RPCs) and Ring-Imaging Cherenkov (RICH) detectors. The separation of fluorinated gases is carried out mainly through membranes, absorbers, or distillation. Two state-of-the-art recuperation systems are briefly described in this paper.

Towards more eco-friendly gaseous detectors

In the last years, the particle detector community faced a new challenge: how to convert existing and future gaseous detectors in more eco-friendly ones. Indeed, several detectors make use of greenhouse gases (GHGs) since they allow achieving excellent performance and long-term stability. With a growing concern on climate change and future restrictions, it is fundamental to look for solutions that can balance detector performance with an eco-friendly approach. CERN was a pioneer in developing strategies to reduce the use of GHGs in particle detection. Three different strategies have been implemented: the use of gas recirculation and recuperation systems for existing and future detector systems and the search of alternative eco-friendly gas mixtures. Thanks to the first two approaches, it is possible to recycle the gas mixture supplied to the detectors and to retrieve GHGs from the used gas mixtures, allowing a reduction of GHG emissions up to 95%–100% at the LHC experiments. By looking at the long-term operation and future particle detector applications, the search of alternative eco-friendly gas mixtures must be envisaged. A big effort is on-going for the C2H2F4 replacement for the Resistive Plate Chamber (RPC) detectors, which nowadays account for most of CERN particle detector emissions. Several eco-friendly gas mixtures have been identified and tested but finding a suitable replacement for the LHC experiments is particularly challenging. Alternatives to SF6, which is the most powerful GHG, are under studies for RPCs in term of detector performance and chemical characterisation. Last point is increasingly crucial since most of the so-called eco-friendly gases belong to the PFAS family which is very likely to be subject to new regulations soon.