Evidence of solution-diffusion-with-defects in an engineering-scale pressure retarded osmosis system

The demand for sustainable energy solutions has driven interest in capturing power from physical activity in fitness settings. This study introduces the SynergyFit Energy Recovery Model, a comprehensive theoretical framework for estimating and optimizing energy recovery across resistance, cardiovascular, and functional training. The model addresses the challenge of effectively harvesting energy in multi-modal exercise environments by identifying distinct recovery patterns: resistance training provides steady yields through consistent force application, while cardiovascular and functional training scale more rapidly with duration due to dynamic movement profiles. Validation against reported energy recovery values confirms the model’s strong predictive robustness and alignment with established trends. For a training session with an average mass (plate and trainer) of 80 kg, the energy recovery results are as follows: Resistance training yields energy recoveries from 9324 J at 1.5 min to 4827.76 J at 5.0 min; Cardio training shows a marked increase, with energy recoveries ranging from 860.82 J at 1.5 min to 31,882.50 J at 5.0 min; Functional training produces energy recoveries from 466.93 J at 1.5 min to 7130.64 J at 5.0 min. The total energy recovery across these modalities ranges from 10,651.76 J to 43,840.90 J, depending on the exercise duration. The sensitivity analysis further demonstrates that increasing exercise mass, higher cardio training velocities, and longer resting periods significantly enhance energy recovery. Notably, cardio training exhibits the highest energy recoverable potential, with cumulative recovery reaching approximately 43.8 kJ per session. These insights highlight the critical role of optimizing exercise duration and parameters to maximize energy recovery. Overall, the novel SynergyFit Energy Recovery Model offers a significant advancement in understanding and improving energy recovery in fitness environments. By integrating multiple exercise modes, this model contributes to more efficient energy utilization and underscores the benefits of parameter optimization for enhanced sustainability in fitness facilities.

Evaluation of low cost cathode materials for treatment of industrial and food processing wastewater using microbial electrolysis cells

Energy recovery from two-stage SWRO plant using PRO without external freshwater feed stream: Theoretical analysis

Mechanical energy fluctuation of the segments of lower limbs during walking has not been fully investigated. It was hypothesized that the segments may work as a pendulum, i.e. the kinetic and potential energies exchanged out of phase. This study aimed to investigate energy changes and recovery during gait in hip replacement patients. The gait data for 12 participants with total hip replacement and 12 age-matched control was compared. The kinetic, potential and rotative energies for whole lower limb and thigh, calf and foot, were calculated. The effectiveness of a pendulum effect was analysed. Gait parameters (speeds and cadence) were calculated. The results showed that the thigh had significant effectiveness as a pendulum during gait with energy recovery coefficient of approximately 40% while the calf and foot were less like a pendulum during gait. In comparison, energy recoveries of lower limbs in the two groups were not significantly different. If the pelvis was considered as an approximate to the centre of mass, however, the control group had a higher energy recovery than total-hip-replacement group by roughly 10%. This study concluded that, unlike centre of mass energy recovery, the mechanical energy recovery mechanism in the lower limbs during walking is not affected after total hip replacement.

Sea water desalination by reverse osmosis: the true needs for energy

Seawater desalination is increasingly being used as a means to augment freshwater supplies in regions with high water stress, and reverse osmosis is increasingly the technology of choice because of the low energy consumption. However, seawater reverse osmosis (SWRO) systems suffer from various types of fouling, which can increase energy consumption and the use of chemicals during SWRO operation. In practice, pre-treatment systems are put in place to reduce the particulate and biological fouling potential of SWRO feed water. However, simple, reliable and accurate methods to assess the extent to which biological fouling potential is reduced during pre-treatment are not available for seawater. This research developed a new method to measure bacterial growth potential (BGP) using the native bacterial consortium in seawater. New reagents to extract and detect ATP in microbial cells were specifically developed for seawater. The new lysis and detection reagents overcame the salt interference in seawater and allow low detection of total ATP, free ATP and microbial ATP in seawater. Incorporating a filtration step further increased the sensitivity of the method six fold, enabling ATP detection of ultra-low levels of microbial ATP in seawater. The newly developed ATP-based BGP method was applied to monitor and assess the pre-treatment of five full-scale seawater desalination plants around the world. A good correlation was observed between BGP measured in SWRO feed water and the pressure drop increase in the SWRO systems, suggesting the applicability of using the ATP-based BGP method as a biofouling indicator in SWRO. Furthermore, a safe level of BGP (<70 µg/L) is proposed for SWRO feed water in order to ensure a chemical cleaning frequency of once/year or lower. However, to validate this conclusion, more SWRO plants with different pre-treatment systems need to be monitored. In the future, on-line monitoring of BGP in SWRO feed water may further reduce the consumption of chemicals and energy and improve the overall sustainability of seawater desalination by reverse osmosis.

Energy recovery through reverse electrodialysis: Harnessing the salinity gradient from the flushing of human urine

Numerical study on the energy consumption characteristics of a novel integrated pump-motor unit for SWRO desalination system

Reverse osmosis (RO) technology has been widely applied to water treatment such as seawater desalination, and large RO plants are many in operation around the world. Moreover, much larger plants will be required to secure sufcient water resource in the near future because global water shortage and quality problems are still getting more serious. Mega-ton Water System project was carried out for sustainable management of water environment and for low-carbon path to develop advanced key technologies of water treatment. Lowpressure RO membrane for seawater desalination has been studied in the project as a part of the core technologies to realize mega plant that is capable of producing 1,000,000 m3 of freshwater per day. Fundamental and scientifc research for RO membranes based on fne structure analyses by means of transmission electron microscopy with a special technique was conducted, and practical tools for designing new innovative RO membrane were acquired by the structure analyses to quantify the physicochemical and chemical properties of RO membranes. As the result of studying on structural design of RO membrane, low pressure SWRO membrane was obtained to reduce energy consumption compared to conventional ones in the past of SWRO. The vision of the “Mega-ton Water System” is sustainable desalination and reclamation. The missions are: 1) energy reduction (20-30%), 2) water production cost reduction (50%), and 3) low environmental impact (fewer chemical operations). Water cycle in “Mega-ton Water System” is separated into two parts including i) Seawater RO (SWRO) system, and ii) Seawater RO system with PRO system. The main challenge of development goal is the construction of mega-ton-scale system for seawater desalination for half the current cost. Accordingly, we developed the world’s frst low-pressure, multi-stage, high yield RO system, using a low-pressure seawater desalination membrane, and as a result of incorporating into it the elemental technologies gained from research in subthemes, such as highly-efcient pressure energy recovery, low-cost and highly durable plastic piping, pretreatment without the use of chemicals.

Several technologies, including pressure-retarded osmosis (PRO), reverse electrodialysis (RED), and capacitive mixing (CapMix), are being developed to recover energy from salinity gradients. Here, we present a new approach to capture salinity gradient energy based on the expansion and contraction properties of poly(acrylic acid) hydrogels. These materials swell in fresh water and shrink in salt water, and thus the expansion can be used to capture energy through mechanical processes. In tests with 0.36 g of hydrogel particles 300 to 600 μm in diameter, 124 mJ of energy was recovered in 1 h (salinity ratio of 100, external load of 210 g, water flow rate of 1 mL/min). Although these energy recovery rates were relatively lower than those typically obtained using PRO, RED, or CapMix, the costs of hydrogels are much lower than those of membranes used in PRO and RED. In addition, fouling might be more easily controlled as the particles can be easily removed from the reactor for cleaning. Further development of the technology and testing of a wider range of conditions should lead to improved energy recoveries and performance.

The correlations among wastewater internal energy, energy consumption and energy recovery/production potentials in wastewater treatment plant: An assessment of the energy balance

A system-level CFD simulation model for investigating the energy dissipation mechanism of seawater pump and rotary energy recovery device in SWRO desalination system

Integration of advanced high-pressure pumps and energy recovery equipment yields reduced capital and operating costs of seawater RO systems

Waste plastic conversion involves the treatment of plastic waste to transform in different forms of energy (heat, electricity, liquid fuels). Plastic can be converted into different forms of biofuel via thermochemical conversion methods (gasification, pyrolysis and liquefaction). Algal biomass can be converted into different forms of biofuel (crude bio-oil, bioethanol, biogas, biodiesel and bio-hydrogen) well as value added chemicals. Microalgal cells can accumulate more lipids over a shorter life cycle, they are discussed as a promising feedstock for third-generation biodiesel. The utilization of microalgae as biofuel feedstocks offers an economic, ecofriendly alternative to the use of fossil fuels the aim of microplastics (MPs) removals. Interactions between MPs and microalgal cells could enhance several important features for possible microalgal harvest and MPs accumulation. One hypothesis is microalgal biomass hypothesis can accumulate lipids and carbohydrates under microplastic stress, supporting biomass conversion into biodiesel and bioethanol. In such systems, algal cells act as bio-scavengers for MPs, binding the particles to algal surfaces or incorporating them into their cells; they are filtered from the water body and finally destroyed by further downstream processing of the polluted biomass. In this study, in order to determine biofuel (1-butanol) and methane gas [CH4(g)] production; High- and low-density polyethylene (HDPE and LDPE), polypropylene (PP), and polyvinyl chloride (PVC) MPs were removed using biomass composed of microalgae Chlamydomonas reinhardtii and Chlorella vulgaris. The algal inhibition test results proved that small groups of MPs with a size of ≈ 100 nm did not show algal inhibition. According to the algae inhibition test results, the production of 1-butanol from 100 mg/l microalgae biomass under aerobic conditions were determined as 93 ml/g for HDPE, 236 ml/g for LDPE, 387 ml/g for PP and 459 ml/g for PVC. According to the algae inhibition test results, the production of CH4(g) from 400 mg/l microalgae biomass under anaerobic conditions were measured as 452 ml/g for HDPE, 510 ml/g for LDPE, 529 ml/g for PP and 541 ml/g for PVC. 91.26%, 94.52%, 98.34% and 96.17% energy recoveries were measured for HDPE, LDPE, PP and PVC MPs, respectively, after microalgae biomass experiments, at pH=7.0 and at 35oC. Maximum 98.34% energy recovery was obtained for PP MPs after microalgae biomass experiments, at pH=7.0 and at 35oC.

Chinese waste incinerators have substantial excess capacity, and it has been suggested that waste from landfills be excavated to increase the energy recovery by using vacant incineration capacity. By means of life cycle assessment (LCA), we assess this suggestion in terms of its climate change impacts. Given the temporal properties of the issue, we used a dynamic LCA approach by specifying emissions and energy recovery for each year over a 100-year period. We then quantified climate change in terms of radiative forcing (W/m2) for each year, in contrast to a traditional LCA approach summarizing emissions and energy recovery over a 100-year period in terms of kg CO2-equivalents. We considered several waste compositions and a range of ages of landfilled waste. The results of dynamic LCA revealed that for a time horizon of 10-50 years, excavation and incineration of landfilled waste is beneficial only for reducing the cumulative radiative forcing if the waste is only 2-3 years old. Waste older than 4 years old should, in all cases, remain in the landfill from a climate change point of view. The traditional LCA approach revealed its shortcomings compared with the dynamic LCA approach. Considering technologies with time-distributed emissions and energy recoveries, we warn against indiscriminate use of the traditional approach when decisions are supposed to contribute to reducing climate change impacts to meet political targets set for the next few decades.