Pilot-scale Demonstrations Research Articles

Unraveling the Potential of Microbial Flocculants: Preparation, Performance, and Applications in Wastewater Treatment

Microbial flocculants (MBFs), a class of eco-friendly and biodegradable biopolymers produced by various microorganisms, have gained increasing attention as promising alternatives to conventional chemical flocculants in wastewater treatment and pollutant removal. This review presents a comprehensive overview of the current state of MBF research, encompassing their diverse sources (bacteria, fungi, and algae), major categories (polysaccharides, proteins, and glycoproteins), production processes, and flocculation performance and mechanisms. The wide-ranging applications of MBFs in removing suspended solids, heavy metals, dyes, and other pollutants from industrial and municipal wastewater are critically examined, highlighting their superior efficiency, selectivity, and environmental compatibility compared to traditional flocculants. Nonetheless, bioflocculants face significant challenges including high substrate costs, low production yields, and intricate purification methodologies, factors that impede their industrial scalability. Moreover, the risk of microbial contamination and the attendant health implications associated with the use of microbial flocculants (MBFs) necessitate thorough evaluation. To address the challenges of high production costs and variable product quality, strategies such as waste valorization, strain improvement, process optimization, and biosafety evaluation are discussed. Moreover, the development of multifunctional MBF-based flocculants and their synergistic use with other treatment technologies are identified as emerging trends for enhanced wastewater treatment and resource recovery. Future research directions are outlined, emphasizing the need for in-depth mechanistic studies, advanced characterization techniques, pilot-scale demonstrations to accelerate the industrial adoption of MBF, and moreover, integration with novel wastewater treatment processes, such as partial nitrification and the anammox process. This review is intended to inspire and guide further research and development efforts aimed at unlocking the full potential of MBFs as sustainable, high-performance, and cost-effective bioflocculants for addressing the escalating challenges in wastewater management and environmental conservation.

On-Site Pilot-Scale Microalgae Cultivation Using Industrial Wastewater for Bioenergy Production: A Case Study towards Circular Bioeconomy.

This case study assesses the valorization of industrial wastewater streams for bioenergy generation in an industrial munition facility. On-site pilot-scale demonstrations were performed to investigate the feasibility of algal growth in the target wastewater on a larger outdoor scale. An exploratory field study followed by an optimized one were carried out using two 1000 L open raceway ponds deployed within a greenhouse at an industrial munition facility. An online system allowed for constant monitoring of operational parameters such as temperature, pH, light intensity, and dissolved oxygen within the ponds. The original algal seed evolved into an open-air resilient consortium of green microalgae and cyanobacteria that were identified and characterized successfully. Weekly measurements of the level of nutrients in pond liquors were performed along with the determination of the algal biomass to quantitatively evaluate growth yields. After harvesting algae from the ponds, the biomass was concentrated and evaluated for oil content and biochemical methane potential (BMP) to provide an estimate of the algae-based energy production. Additionally, the correlation among biomass, culturing conditions, oil content, and BMP was evaluated. The higher average areal biomass productivity achieved during the summer months was 23.9 ± 0.9 g/m2d, with a BMP of 350 scc/gVS. An oil content of 22 wt.% was observed during operation under low nitrogen loads. Furthermore, a technoeconomic analysis and life cycle assessment demonstrated the viability of the proposed wastewater valorization scenario and aided in optimizing process performance towards further scale-up.

Replacement reactions for carbon geosequestration may be faster in calcium olivine vs magnesium olivine

CO2 mineralization is the safest CO2 geosequestration method with the highest sequestration capacity. Even though there have been lab and pilot-scale demonstrations, the complex chemical reaction is still elusive at atomic level. Here, I show that the ab initio molecular dynamics (AIMD) and metadynamics simulations enable quantitative analysis of reaction pathways, thermodynamics, and kinetics of the Mg2+ and Ca2+ ion dissolutions from olivine minerals, which have high weathering potential for carbonation process. The leaching of Ca2+ from the Ca-olivine surface is a ligand exchange process that results in a much lower energy barrier with 103 times faster dissolution rate compared to the leaching of Mg2+, which the tight magnesium sites on the forsterite (Mg-olivine) surface forbid ligand exchange. These results provide indication on water capabilities in solvating Ca2+ and Mg2+ that are relevant to mineral carbonation and can help the evaluation of potential enhanced CO2 mineralization mechanisms.

Prospects for commercial microalgal biorefineries: Integrated pilot demonstrations and process simulations based techno-economic assessment of single and multi-product value chains

Pilot-scale demonstrations and techno-economic simulations are proposed for overcoming uncertainties surrounding technology scale-up impacts and economics of microalgae (MA) biorefineries. Therefore, to contribute to knowledge on promising value chains regarding near-term commercialization, this study investigated the techno-economic performances of alternate commercial (1–10 t MA/d) spirulina MA biorefinery scenarios via integrated pilot demonstrations and Aspen Plus® process simulations. The scenarios include spirulina cultivation and processing into: (I) dried spirulina food product (DSFP), (II) phycocyanin (PCN), (III) PCN + biostimulant for plants (BFP), (IV) 50:50 % MA feedstock split for DSFP and PCN + BFP, and (V) similar to IV but integrated with cattle-dung biogas heat system (CDBHS) allowing for additional liquid biofertilizer recovery. DSFP prices of 13.2–17.3 €/kg (4-fold to 5-fold lower vs market average) were sufficient for profitability of I. Conversely, II and III were unprofitable per the relatively high PCN prices projected for viable operations (283–544 €/kg PCN vs market prices at 170–280 €/kg PCN). Integration of DSFP into the PCN + BFP (IV) plus CDBHS (V) resulted in economically viable biorefineries. Thus, for near-term commercial applications, the integration of the DSFP into the spirulina biorefineries could be strategic for advancing viable productions of the emerging PCN and BFP products. Optimization opportunities for the MA cultivation (e.g. achieved productivity of 8.6 g/m2.d vs reports of 14 g/m2.d) and the downstream processing (e.g. attained PCN yield of 6 % vs theoretical 11 %) could be explored to improve the biorefinery cost and revenues [e.g. 11 % PCN yield corresponds to comparable PCN prices vs the market, i.e. 250–296 €/kg (II) and 154–193 €/kg (III)]. Hence, although the multi-product biorefinery schemes (III-V) could improve the bioresource utilization efficiency, their near-term economic viability will depend largely on the values of the products and technology efficiencies rather than the number of products recovered.

A critical literature review on biosolids to biochar: an alternative biosolids management option

The biosolids management is becoming an increased concern for the wastewater sector in recent times due to production of large volume of biosolids, their higher processing costs and the presence of emerging contaminants. The pyrolysis of biosolids is gaining significant interest in the industry sector as well as research community over the last decade due to its ability to reduce biosolids volume, produce high-value biochar product and minimise the risk associated with contaminants. This paper aims to critically review the literature on biosolids management techniques and their current challenges, biosolids characteristics and its suitability for pyrolysis, pyrolysis product characterisation from different reactor designs and biochar application as a soil amendment, adsorbent and catalyst. The efforts have also been made to critically summarise studies on the process modelling activities and techno-economic assessments including some key pilot-scale demonstrations of recent time. The review concludes that biosolids to biochar can be an effective alternative to biosolids management; however, its commercial viability is limited in the current scenario. In the end, efforts have been made to highlight current challenges including research gaps and future perspectives in improving its commercial viability.

Continuous flow, large‐scale, microbial fuel cell system for the sustained treatment of swine waste

Microbial fuel cells (MFCs) have long held the promise of being a cost-effective technology for the energy-neutral treatment of wastewater. However, successful pilot-scale demonstrations for this technology are still limited to very few. Here, we present a large-scale MFC system, composed of 12 MFCs with a total volume of 110L, successfully treating swine wastewater at a small educational farm. The system was operated for over 200days in continuous mode with hydraulic residence time of 4hr. Very stable electrochemical and waste treatment performance was observed with up to 65% of chemical oxygen demand (COD) removed and a maximum treatment rate of 5.0kgCOD/m3 .day. Robust microbial enrichment was performed and adapted to metabolize and transform a diversity of compounds present. The Net Energy Recovery (NER=0.11kWhr/kg COD) is not only competitive with conventional cogeneration processes, but is in fact sufficient to sustain the operational energy requirements of the system. PRACTITIONER POINTS: This study demonstrates the design and operation of a large-scale microbial fuel cells (MFC) system for continuous treatment of swine wastewater. The system achieved a high chemical oxygen demand removal rate within a short hydraulic residence time. This study moves one-step closer to applying MFC technology for real wastewater treatment.

Sustainable Primary Aluminium Production: Technology Status and Future Opportunities

Energy and greenhouse gas emission remain the major technological challenges to the aluminium production. Over the last few decades, aluminium industries have been aiming for higher production volumes through capacity creep in the existing smelters with reasonable additional investment. However, a strong focus on specific energy consumption has always been part of technology considerations, and this aspect is even more critical today from the point of view of long-term sustainability. Through research and innovations in design, control and operations of Hall–Heroult cell, modern smelters are achieving a benchmark performance as low as 13 kWh/kg of Al at commercial scale and 12 kWh/kg of Al at pilot scale. There is also significant research effort put on alternate technology platforms like drained cathode cell and inert anode. Although there are many pilot-scale demonstrations, many critical issues like operating cost and stability problems in drained cell and higher specific energy in inert anode need to be addressed for commercial consideration of these technologies. Industry 4.0 platform technologies like internet of things, cloud computing, machine learning and artificial intelligence, etc., are opening up further opportunities for benchmark performance to the modern smelters. Digital twin is such an emerging technology for predictive control and operation and will be a key driver for low-energy cells. Based on a discussion on the status of present technology, this article presents a comprehensive review of the technological progress of aluminium smelting and emerging new technology like Industry 4.0, towards reduction of energy and making aluminium production sustainable.

Demonstration of energy-saving membrane bioreactor (MBR) systems.

Membrane bioreactors (MBRs) have the advantages of achieving excellent effluent quality, a small footprint and smooth operation and maintenance. On the other hand, its high energy consumption remains a critical challenge for MBR application. Japan Sewage Works Agency has conducted a series of joint researches with several private companies since 2012 and developed four kinds of energy-saving MBR systems. Based on the results of long-term pilot-scale demonstrations, specific energy consumption (SEC) per unit treated effluent volume was calculated for each MBR system, resulting in all systems achieving SEC of 0.4 kWh/m3 or less. To meet an additional requirement for expanding MBR application, it is also necessary to establish the applicability of MBR systems to combined sewer systems, suffering from occasional inflow fluctuation caused by rainfall. The capability of temporary higher flux operation during and after rainy weather was also demonstrated with three of the four developed systems.

Economic assessment of hydrogen production from solar driven high-temperature steam electrolysis process

Abstract A key prerequisite for the hydrogen economy is cost-effective renewable hydrogen supply. This paper provides a framework for the thermodynamic and economic assessment of solar hydrogen production from the high-temperature steam electrolysis (HTSE) route. A system configuration for the solar-driven steam electrolysis plant is proposed. The thermodynamic and economic analysis is done for varying temperature and current density conditions of the solid oxide electrolyzer powered by concentrated solar (CSP) and photovoltaic (PV) power plants. Based on the expected reductions in the cost of plant components, the levelized cost of hydrogen (LCOH2) for the 2030 scenario is evaluated. Conditions for the viability of this route are checked by comparing the results with the polymer electrolyte membrane electrolysis (PEME) process. The optimum energy efficiency of a PV driven process increases from 9.1% at 873 K, 1500 A/m2 to 12.1% at 1273 K, 8000 A/m2. For the electrolyzer operating at 873 K, the optimum LCOH2 of 22 $/kg is obtained at 6000 A/m2. For the electrolyzer temperature of 1073 K, LCOH2 drops from 16 $/kg at 5000 A/m2 to 12.1 $/kg at 10000 A/m2. When compared to PEME, this route becomes viable beyond 973 K, 6000 A/m2 for PV and 923 K, 3000 A/m2 for CSP driven processes. With the current state of economics, this process is not competitive with the industrial steam methane reforming route. However, the cost target of 6–8 $/kg is achievable if the component costs reduce to 2030 level. Thus, the process has potential to be commercially viable and should be pursued further by creating prototype and pilot scale demonstrations.

Impact of Flue Gas Compounds on Microalgae and Mechanisms for Carbon Assimilation and Utilization.

To shift the world to a more sustainable future, it is necessary to phase out the use of fossil fuels and focus on the development of low-carbon alternatives. However, this transition has been slow, so there is still a large dependence on fossil-derived power, and therefore, carbon dioxide is released continuously. Owing to the potential for assimilating and utilizing carbon dioxide to generate carbon-neutral products, such as biodiesel, the application of microalgae technology to capture CO2 from flue gases has gained significant attention over the past decade. Microalgae offer a more sustainable source of biomass, which can be converted into energy, over conventional fuel crops because they grow more quickly and do not adversely affect the food supply. This review focuses on the technical feasibility of combined carbon fixation and microalgae cultivation for carbon reuse. A range of different carbon metabolisms and the impact of flue gas compounds on microalgae are appraised. Fixation of flue gas carbon dioxide is dependent on the selected microalgae strain and on flue gas compounds/concentrations. Additionally, current pilot-scale demonstrations of microalgae technology for carbon dioxide capture are assessed and its future prospects are discussed. Practical implementation of this technology at an industrial scale still requires significant research, which necessitates multidisciplinary research and development to demonstrate its viability for carbon dioxide capture from flue gases at the commercial level.

Integrated Sustainability Assessment of CCS – Identifying Non-technical Barriers and Drivers for CCS Implementation in Finland

The aim of the paper is to discuss the sustainability of CCS technologies from a cross-disciplinary point of view. Due to the complex nature of the current sustainability challenges, such as climate change, which is the key driver for the development of CCS, trans-disciplinary research approaches are required to ensure that all relevant knowledge from disciplines and actor groups related to the problem is incorporated. The findings of the paper are based on a sustainability assessment conducted as part of a Finnish research project Carbon Capture and Storage Program (CCSP). The findings are analysed and integrated using the PESTEL framework, in which most important drivers and barriers having an impact on the general environment and on the potential implementation of CCS technologies in Finland are analysed. The results of the PESTEL analysis indicate that significant barriers at the moment lie in the economic and legal categories. Instead of fossil energy production, carbon capture and utilisation, or bio-CCS could perhaps be viable solutions in Finnish conditions. However, barriers related to price and legal framework would need to be overcome in these cases. Clear policy drivers could act as motivators for the industry and for the academia to continue development of the most potential and promising solutions, and would require ensuring availability of funding for pilot scale demonstrations. However, decision to invest in CCS is not only a technological, economical or legal question, but also an environmental, social, and even ethical question that relates to public acceptance and on the principles of sustainable development. In future, more attention should be paid to the interrelatedness of social and technical aspects of CCS, since open questions regarding the role and potential of CCS in moving towards low carbon future in Finland remain.

Guidelines for Utilities Wishing to Conduct Pilot-Scale Demonstrations

Guidelines for Utilities Wishing to Conduct Pilot-Scale Demonstrations

Ultrasonic Melt Processing: Opportunities and Misconceptions

Ultrasonic melt processing enjoys the revival of interest in the last 1015 years. Although the main fundamental works as well as lab-scale and pilot-scale demonstrations date back to the 1950-1980s, the ultrasonic melt processing of light metals has not become a major technology. Recently the deficiencies of current technological approaches brought back the interest to ultrasonic treatment for degassing, grain refinement and composite materials. The current attempts to repeat the earlier results, to gain more fundamental insight using advanced means available and to up-scale the positive effects to the industrial scale show frequent lack of understanding of the basic controlling mechanisms. This paper describes the main mechanisms of ultrasonic melt processing, shows frequent mistakes, and gives some guidelines for technology up-scaling. The paper is illustrated with the latest experimental results.

Persulfate Oxidation Activated by Peroxide with and without Iron for Remediation of Soil Contaminated by Heavy Fuel Oil: Laboratory and Pilot-Scale Demonstrations

The main objective of this study was to evaluate and optimize the chemical oxidation process to be implemented at a power plant in Penghu County, Taiwan through laboratory and pilot-scale experiments were used to evaluate and optimize the chemical oxidation process at a power plant in Penghu County, Taiwan. Prior to pilot test, bench-scale tests were performed in the laboratory and analytical results indicated that persulfate oxidation achieved 90% removal of fuel oil while Fenton-like oxidation achieved only 41% removal of fuel oil within three days of testing period. Persulfate oxidation coupled with Fenton-like reaction was then used in a pilot test to treat the contaminated soil onsite. The Fenton-like reaction served the first stage of oxidation which formed hydroxyl radicals to break down fuel oil. The excess heat and ferrous ions resulted from such oxidation process would then activate persulfate oxidation which, in turn, produced sulfate radicals for continual brake-down of fuel oil. Result of soil pilot test indicated that the concentration of fuel oil was reduced to below the regulated standard in less than a week. Because the treated soil was originated from the local basaltic basement rock, it is rich in heavy metals, by nature. As such, the heavy metals as nickel and chromium were detected in leachate collected from the treatment cells, at concentrations exceeding the Taiwan Contaminant Control Standard and would have posed secondary contamination to the ambient environment if in-situ soil persulfate oxidation was implemented. Therefore, the result of this case study provides an alert that implementation of in-situ persulfate oxidation for soil and groundwater treatment could pose a threat of secondary contamination of heavy metals to the ambient environment.

Secondary aggregate from waste treated with carbon dioxide

Secondary aggregate can be made from industrial waste by treatment with carbon dioxide gas (accelerated carbonation). Trials were conducted on bauxite waste, biomass ashes, metal dusts, quarry fines, steel-making waste, and the ashes arising from municipal incineration, paper recycling, sewage sludge incineration, and coal fired power stations. The wastes were formed into pellets using a combined pelletising and accelerated carbonation process with patent pending. The manufactured pellets conformed to the bulk density requirements for lightweight aggregate specified by British Standard. Specification for lightweight aggregate is limited, and two commercial lightweight aggregates were tested alongside the manufactured pellets for comparison. Compressive strength, water absorption and apparent density of the materials were comparable to that of the commercial aggregate. Furthermore, the finished product contained up to 11% of its own weight in carbon dioxide gas, permanently bound as solid minerals. In a series of on-site pilot scale demonstrations, aggregates have been produced in bulk and used in commercial product trials. The aggregates produced by accelerated carbonation appear to be suitable for use in a wide range of applications including concrete, construction blocks, and substrates for green roofs.

Value added products from reclamation of military munitions

The Department of Defense has a backlog of excess, obsolete and unserviceable munitions for disposal. For many of these munition items the only method of disposal is open burning/open detonation (OB/OD) which destroys valuable resources which can be reclaimed and converted to useful products. The Crane Division, Naval Surface Warfare Center (NAVSURFWARCENDIV Crane) in support of the Navy's Ordnance Reclamation Program and the Joint Service Large Rocket Motor Disposal Program has been developing technology for the removal and reclamation of the energetics from munitions. The University of Missouri-Rolla has demonstrated the use of high pressure waterjet technology for removal of PBX explosives from projectiles and warheads. Development work is nearing completion for demonstrating the capability to remove Class 1.1 propellant from strategic rocket motors using high pressure waterjets. Current projects are under way focusing on resource recovery and recycling (R3) of the reclaimed energetics while minimizing disposal. The current reclamation projects include reformulation of the explosives and Class 1.1 propellants into commercial blasting agents, reuse of Navy gun propellant for various applications including agriculture and oil-gas well stimulation. Other projects include the recovery of RDX/HMX from Class 1.1 explosives and propellants and the conversion of Explosive D into higher value products. Lab/bench scale testing has been completed on many of these processes, and for some pilot scale demonstrations have been or are scheduled to be completed during 1997.

Experience and Plans for Rationalization of Small-Scale Fisheries in India

Small-scale fisheries have traditionally been the backbone of the fishing industry all over the world. Although large-scale mechanized fishing has come into the limelight recently, even such countries as have developed substantial capability in this direction still have a large fleet of small boats in coastal areas. The landings of this sector of the industry are always substantial, and in many countries they still dominate the picture. In India, small-scale fisheries landed almost 1.15 million tons in 1971. This figure has been increasing as motor-powered small craft have increased in numbers, although 70% of marine fish is still caught from nonpowered boats. Measures taken to increase fishing capacity, landings, and net fishermen’s income over the past 10 years include various kinds of loans and subsidies for the purchase of boats, motors, and nets; assistance for the construction of ponds in inland areas; organization of cooperatives; training programs for fishermen and supporting personnel, especially motor repairmen (with the cooperation of Norway); and gear and vessel research including pilot-scale demonstrations with new types of vessels and equipment.