Mass Balance Analysis Research Articles

Hybrid of machine learning-based multiple criteria decision making and mass balance analysis in the new coconut agro-industry product development

Hybrid of machine learning-based multiple criteria decision making and mass balance analysis in the new coconut agro-industry product development

A transient performance evaluation of a porous evaporative cooler for preservation of fruits and vegetables

A transient performance of a porous evaporative cooling system was carried out using mathematical models developed from the first principles. The models are based on energy and mass balance analysis on different sections of the evaporative cooler. The developed models were solved using a FlexPDE computational fluid dynamics analyzer, based on the finite element, to generate numerical solutions. The models developed were validated using experimental data from a properly designed, constructed, and tested an evaporative cooler and subsequently used to determine the evaporative cooler performance during four different periods of the year covering the two major climatic seasons experienced in Nigeria. Results obtained showed a reduction in the storage chamber temperature by up to 9 °C from the ambient air condition which was within the range of 22–33 °C. Furthermore, it was observed that it performs best during the dry seasons as compared to the wet season. However, during both seasons, the cooling chamber temperature significantly remained below the ambient value. Thus, the evaporative cooler can serve as an effective means of reducing heat-induced post-harvest losses incurred by farmers while also helping in combating climate change since it uses only water and does not require any external energy input.

Lean blowoff dynamics in bluff body stabilized flames: unsupervised classification and balance analysis

Lean blow-out (LBO) is a critical phenomenon in gas turbines. It is enhanced by very to ultra-lean operating conditions which are considered today to decrease the environmental impact of combustion. Despite many studies on the subject, the physical mechanisms leading to global flame extinction are not fully understood. Recently, unsupervised classification has appeared in the literature as an efficient tool to identify key features in reactive flows. In this work, unsupervised classification relying on Principle Component Analysis (PCA) and K-means clustering algorithms is used to investigate the underlying mechanisms of a blowoff event in a bluff body configuration. The unsupervised classification allows to identify and track in time 4 distinct zones: fresh gases, burnt gases, fast reacting flame and preheat zone. To elucidate the blow-out processes, an analysis of mass and energy balances of the different zones is proposed. This analysis describes the temporal evolution of the zones as a result of their interactions, which is the main driver for flame stabilization or blowoff. For the considered blowoff event, the extinction is induced by an imbalance between the various contributions identified by the proposed analysis: while the decrease in fuel mass flow rate modifies both the conductive fluxes and chemistry source terms in the reactive zones, the convective fluxes remain constant over time as the total mass flow rate is kept constant. This work suggests that the proposed methodology is a useful tool to analyze unsteady configurations and understand the main mechanisms at work in such configurations.

Development of an economically viable plastic recovery waste management system in Cibodas and Padamukti Village, West Java

Out of the 2,142 existing community-managed sorting and recycling facilities in Indonesia, known as TPS-3R, only 14% are functioning optimally due to economic challenges, highlighting the need for financially viable TPS-3R. To address this issue, the research aims to recommend an economically viable plastic recovery waste management system with optimum residue and income. Cibodas and Padamukti Villages are chosen as the case study location, as it has only 20% waste collection coverage and is located in the Citarum Watershed, whose river is a source of water for 60 million people and is part of the Citarik Ecotourism Living Lab. Primary data collection was carried out through interviews with recyclers in the villages and through waste volume and composition characterization. Three scenarios were developed for the Plastic Recovery Facility (PRF) objectives: Scenario 1 (S1) serves as the baseline of PRF, Scenario 2 (S2) buys plastic wastes from existing traders to be processed with more advanced plastic recycling technologies, and Scenario 3 (S3) is a self-sustaining PRF that could be replicated for the whole villages. Data analysis involved mass balance, financial models, BCR, NPV, and multicriteria decision-making. The residue disposed of in landfills is 32%, 17%, and 28% of the total waste managed for S1, S2, and S3. Financial modeling yielded BCR values of 1.06, 1.15, and 1.24, as well as NPV +IDR78,036,332; +IDR465,224,754; and +IDR354,414,072. The results highlight the importance of detailed analysis of mass balance and financial modeling according to the waste composition in any TPS-3R location, especially the differences in the value of rigid and flexible plastics, which will affect the types of technology and products. While the recommended scenario, S3, does not eliminate the need for capital investment from the government, it provides a framework to plan PRF with an operating surplus, which will increase the community’s willingness to run it and ensure the PRF’s long-term functionality to yield social and environmental benefits.

How to handle glacier area change in geodetic mass balance

Abstract Innovations in geodesy enable widespread analysis of glacier surface elevation change and geodetic mass balance. However, coincident glacier area data are less widely available, causing inconsistent handling of glacier area change. Here we quantify the bias introduced into meters water equivalent (m w.e.) specific geodetic mass balance results when using a fixed, maximum glacier area, and illustrate the bias for five North American glaciers. Sites span latitudes from the northern U.S. Rocky Mountains (48°N) to the Central Alaska Range (63°N) between 1948 and 2021. Results show that fixed (maximum) area treatment subdues the m w.e. mass change signal, underestimating mass balance by up to 19% in our test cases. This bias scales with relative glacier area change and the mass balance magnitude. Thus, the bias for specific geodetic mass balances will be most pronounced across rapidly deglaciating regions. Our analysis underscores the need for temporally resolved glacier area in geodetic mass balance studies.

Achieving ultra-high nitrogen and phosphorus removal from real municipal wastewater in a novel continuous-flow anaerobic/aerobic/anoxic process via partial nitrification, endogenous denitrification and nitrite-type denitrifying phosphorus removal

Achieving economic and efficient removal of nutrients in mainstream wastewater treatment plants (WWTPs) continues to be a challenging research topic. In this study, a continuous-flow anaerobic/aerobic/anoxic system with sludge double recirculation (AOA-SDR), which integrated partial nitrification (PN), endogenous denitrification (ED) and nitrite-type denitrifying phosphorus removal (nDNPR), was constructed to treat real carbon-limited municipal wastewater. The average effluent concentrations of total inorganic nitrogen (TIN) and PO43−-P during the stable operation period were 1.8 and 0.3 mg/L, respectively. PN was achieved with an average nitrite accumulation ratio of 90.4 % by combined strategies. Adequate storage of polyhydroxyalkanoates and glycogen in the anaerobic zone promoted the subsequent nitrogen removal capacity. In the anoxic zone, nitrite served as the main electron acceptor for the denitrifying phosphorus removal process. Mass balance analysis revealed that nDNPR contributed to 23.6 % of TIN removal and 44.7 % of PO43−-P removal. The enrichment of Nitrosomonas (0.45 %) and Ellin 6067 (1.31 %), along with the washout of Nitrospira (0.15 %) provided the bacterial basis for the successful implementation of PN. Other dominant endogenous heterotrophic bacteria, such as Dechlormonas (10.81 %) and Candidatus Accumulibacter (2.96 %), ensured simultaneous nitrogen and phosphorus removal performance. The successful validation of integrating PN, ED and nDNPR for advanced nutrient removal in the AOA-SDR process provides a transformative technology for WWTPs.

Achieving simultaneous removal of carbon and nitrogen by an integrated process of anaerobic membrane bioreactor and flow-through biofilm reactor

In this study, a combined system consisting of an anaerobic membrane bioreactor (AnMBR) and flow-through biofilm reactor/CANON (FTBR/CANON) was developed to simultaneously remove carbon and nitrogen from synthetic livestock wastewater. The average removal efficiencies of total nitrogen (TN) were 64.2 and 76.4% with influent ammonium (NH4+-N) concentrations of approximately 200 and 500 mg/L, respectively. The COD removal efficiencies were higher than 98.0% during the entire operation. Mass balance analysis showed that COD and TN were mainly removed by the AnMBR and FTBR/CANON, respectively. The anammox process was the main nitrogen removal pathway in the combined system, with a contribution of over 80%. High functional bacterial activity was observed in the combined system. Particularly, an increase in the NH4+-N concentration considerably improved the anammox activity of the biofilm in the FTBR/CANON. 16S rRNA high-throughput sequencing revealed that Methanosaeta, Candidatus Methanofastidiosum, and Methanobacterium were the dominant methanogens in the AnMBR granular sludge. In the CANON biofilm, Nitrosomonas and Candidatus Kuenenia were identified as aerobic and anaerobic ammonium-oxidizing bacteria, respectively. In summary, this study proposes a combined AnMBR and FTBR/CANON process targeting COD and nitrogen removal, and provides a potential alternative for treating high-strength wastewater.

Ultrafiltration (UF) and biological oxygen-dosed activated carbon (BODAC) filtration to prevent fouling of reversed osmosis (RO) membranes: A mass balance analysis

(Bio)fouling is the most common problem in membrane processes used in water production. It is also a reported unavoidable problem, with mitigation strategies being frequently ineffective in addressing this problem. An ultrapure water plant (UPW) in Emmen (The Netherlands), fed with secondary effluent, comprises the following subsequent treatment steps: ultrafiltration (UF), biological oxygen-dosed activated carbon (BODAC) filtration and reverse osmosis (RO). The BODAC filters were designed to prevent fouling in RO membranes, and for ten years, they have been operated without significant fouling issues. The present work aims to provide insight into the role of the full-scale UF + BODAC in fouling prevention, by conducting a mass balance (MB) analysis to assess the removal/release of common fouling precursors. Positive MB results were noticed for particulate organic compounds, iron (Fe) and manganese (Mn) meaning their constant removal in the UF + BODAC. The UF + BODAC was shown to be an effective nitrification system, effectively converting all the ammonium and nitrite to nitrate. In conclusion, the combined removal of organics, Fe, and Mn species and nitrification by UF + BODAC is most likely an important factor in downstream fouling prevention, making this system an attractive process for fouling prevention. Nevertheless, further investigations to discover the mechanisms involved are needed.

Assessing the efficacy and mechanisms of glycol-contaminated water treatment through floating treatment wetlands

Abstract The growing concerns surrounding water pollution and the degradation of ecosystems worldwide have led to an increased use of nature-based solutions (NbSs). This study assessed the feasibility of using floating treatment wetlands (FTWs) as an NbS to treat propylene glycol-contaminated water and quantitatively investigated different removal pathways. With an environmentally relevant concentration of propylene glycol (1,250 mg/L), FTWs containing Acorus calamus and mixed species demonstrated the highest average glycol mass removal efficacy (99%), followed by Carex acutiformis (98%), Juncus effusus (93%), and the control group without plants (10%) after 1 week. Additional mesocosm-scale experiments with varying FTW configurations, including surface coverage to reduce evaporation and photodegradation processes, and the addition of antibiotics to inhibit microbial activity, were conducted to quantify glycol removal pathways. Mass balance analysis results revealed that microbial biodegradation (33.3–39.7%) and plant uptake (37.9–45.2%) were the primary pathways for glycol removal. Only 15.5–19.5% of the glycol removal via evaporation and photodegradation was accounted in this study, which may be attributed to the mesocosm experimental setup (static water and no wind). Aligned with the broader discussion regarding biodiversity improvements and carbon storage capacity, this study demonstrated that FTWs are an environmentally friendly and effective NbS for addressing glycol-contaminated water.

Comparing Vegetation and Substrate Performances on Nutrient Removal and Biomass Establishment Using a Natural Swimming Pool Experiment

Natural swimming pools (NSPs) rely on the interaction of bog vegetation, bacteria, and substrate to maintain water quality. Nitrogen (N) and phosphorus (P) levels in NSPs are critical because of their involvement in eutrophication. We conducted a 15-week greenhouse study to address the significant literature gap regarding nutrient removal capabilities of substrates and vegetation in the low-nutrient environment of NSPs. We used mass balance analyses to compare the performances of four substrates [river gravel (control), recycled glass, expanded clay, expanded shale] and two plant species [blue flag iris (Iris versicolor) and lizard’s tail (Saururus cernuus)] under two flow conditions: free water surface and subsurface flow. At the end of the experiment, except for the recycled glass group, all other substrate groups reduced water nitrate (NO3) levels to less than 30 mg⋅L−1, the standard of the 2011 Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau (FLL) guidelines. However, only the expanded clay group closely approached the P standard (≤0.01 mg⋅L−1). Expanded clay and expanded shale demonstrated potential as substrates for NSP bogs. The final aboveground biomass dry weight was strongly negatively correlated with the final NO3 and P water concentrations. However, direct plant uptake proved insufficient to remove all nutrient inputs, especially for P. Except for the recycled glass group (34%), a significant portion of N (79%–90%) from total N added was removed by aboveground biomass. However, P uptake by biomass was substantially lower (18%–37%). With acceptable vigor and biomass accumulation, blue flag iris may be a suitable species for vegetated NSPs, whereas lizard’s tail is not because of uncertain establishment. Compared with controlling N, managing P for FLL standards in NSPs will be more challenging. Our work begins to fill the essential gap in the NSP literature regarding nutrient removal capabilities of substrates and vegetation. Future work should continue to study alternative substrates and plant species for P removal, particularly in field conditions and over longer periods.

Sustainable in situ ammonia recovery from municipal solid waste leachate in a single-stream microbial desalination cell

Municipal solid waste (MSW) leachate is one of the most hazardous waste streams leading to great potential risk to environment, and a renewable resource with high concentrations of organic contaminant and ammonia. High energy consumption and chemical input are still the challenges for ammonia recovery from MSW leachate. Here, a single-stream microbial desalination cell (SMDC) was successfully developed for simultaneous energy extraction from organic contaminant and in-situ energy utilization for ammonia recovery. 70% of the organic contaminant from the actual MSW leachate was removed, and 24.9% of the total ammonia was recovered as high-purity (NH4)2SO4. The additional desalination chamber introduced into the SMDC can potentially enhance the NH4+ migration that was determined by the NH4+ concentration gradient and electric field. More than 30% of the total nitrogen was lost, as revealed by nitrogen mass balance analysis, probably resulting from the anodic denitrification process driven by denitrifying microorganisms, e.g., Thauera, which thrived in the anode chamber. Concomitantly, the chemical input for ammonia stripping can be reduced by up to 68% due to the relatively low buffer capacity of the catholyte and the OH− production from the cathode reaction. This SMDC can be an effective and environmentally sustainable solution for MSW leachate treatment and resource recovery.

Full-scale upgrade activated sludge to continuous-flow aerobic granular sludge: Implementing microaerobic-aerobic configuration with internal separators

Aerobic granular sludge (AGS) has been successfully used in sequencing batch reactors. However, their application to existing continuous-flow systems remains challenging. In this study, a novel microaerobic-aerobic configuration with internal separators was implemented in a full-scale municipal wastewater treatment facility with a nominal capacity of 2.5 × 104 m3 d−1. Sludge characteristics, pollutant removal and associated pathways, shifts in the microbial community, and underlying granulation mechanisms were investigated. Following a two-month operation period, the transition from flocculent-activated sludge to well-defined AGS with distinct boundaries and compact structures was successfully achieved. The average size of sludge increased from 31.9 to 138.5 μm, with granules larger than 200 μm constituting 28.9 % of the total sludge and SVI30 averaging 51.4 ± 8.2 mL g−1. The 95th percentile effluent COD, NH4+-N, and TN concentrations were 35.0, 1.2, and 13.3 mg L−1, respectively. The primary pathways for pollutant removal were identified as simultaneous nitrification, denitrification, and phosphorus removal within the microaerobic tanks. The enrichment of denitrifying phosphorus-accumulating organisms, including Hydrogenophaga, Accumulibacter, Azospira, Dechloromonas, and Pseudomonas, provides an essential microbial foundation. Furthermore, computational fluid dynamics modeling revealed that the incorporation of internal separators in aerobic tanks induced shifts in the flow pattern, transitioning from a single-circulation cell to multiple vortical cells. This alteration amplified the local velocity gradients, generating the required shear forces to drive granulation. Moreover, mass balance analysis revealed that the microaerobic and aerobic tanks operated under feast and famine conditions, respectively, creating a microbial selection pressure that favored granulation. This process eliminates the need for external clarifiers, resulting in a footprint reduction of 38.2 % and one-third energy savings for sludge reflux. This study offers valuable insights into the application of continuous-flow AGS to upgrade existing activated sludge systems with limited retrofitting requirements.

Catalytic stepwise pyrolysis for dechlorination and chemical recycling of PVC-containing mixed plastic wastes: Influence of temperature, heating rate, and catalyst

The viability of pyrolysis technology for chemical recycling of plastics is challenged by the presence of PVC in real-world mixed plastic wastes. This study aims to investigate catalytic stepwise pyrolysis as a pretreatment step to remove chlorine from PVC-containing plastic wastes prior to further processing. TG-FTIR and Py-GCMS analysis as well as experiments on a lab-scale pyrolysis system were conducted to study the influence of key processing parameters on the pretreatment including temperature, heating rate, and catalysts. Py-GCMS results indicated 300 °C to be the best pretreatment temperature in terms of balancing Cl removal and avoidance of organochloride formation. Metal oxides, i.e., CaO and Fe2O3, mainly acted as adsorbents of HCl gases with little cracking effect, and their adsorption effects are positively correlated with alkalinity. ZSM-5 catalysts promoted the release of HCl, and the dechlorination effect was more pronounced with ZSM-5 of higher acidity. In contrast, in the lab-scale pyrolysis system, 350 °C pretreatment achieved the highest HCl generation ratio, i.e., 43.60 %. The addition of zeolite catalyst significantly reduced the content of organochloride in the pyrolysis oil in contrast to the performance of metal oxides, but also absorbed most HCl instead of promoting HCl release as in Py-GCMS tests. Mass balance analyses revealed that the majority of chlorine was retained in the solid residues following the catalytic stepwise pyrolysis process, with the notable exception of Fe2O3. ZSM-5(25) catalyst combined with 350 °C pretreatment temperature and 550 °C final pyrolysis achieved the lowest chlorine content in the pyrolysis oil, i.e., 20 ppm, among different process conditions.

Most large structural variants in cancer genomes can be detected without long reads

Short-read sequencing is the workhorse of cancer genomics yet is thought to miss many structural variants (SVs), particularly large chromosomal alterations. To characterize missing SVs in short-read whole genomes, we analyzed ‘loose ends’—local violations of mass balance between adjacent DNA segments. In the landscape of loose ends across 1,330 high-purity cancer whole genomes, most large (>10-kb) clonal SVs were fully resolved by short reads in the 87% of the human genome where copy number could be reliably measured. Some loose ends represent neotelomeres, which we propose as a hallmark of the alternative lengthening of telomeres phenotype. These pan-cancer findings were confirmed by long-molecule profiles of 38 breast cancer and melanoma cases. Our results indicate that aberrant homologous recombination is unlikely to drive the majority of large cancer SVs. Furthermore, analysis of mass balance in short-read whole genome data provides a surprisingly complete picture of cancer chromosomal structure.

Oxidation of sulfide mineral and metal extraction analysis in the microwave-assisted roasting pretreatment of refractory gold ore

The recovery of gold from refractory ore could guarantee sustainable development in the gold industry. However, there are many challenges in the treatment of ore, such as environmental pollution and low recovery. In this regard, the current research focuses on the pretreatment of refractory gold ore and investigates the effect of microwave power, the role of additives, and water on the oxidation and decomposition of sulfide minerals. Pretreatment using microwave-assisted roasting with NaClO3 as an additive to the oxidizing agent is a new method of processing refractory gold ore. Oxidation was studied through sulfur and chlorine mass balance analysis and the degree of metal extraction from sulfide minerals. SEM analysis was carried out to complete the study of the phase change of compounds in the oxidation of mineral sulfides. Roasting of refractory gold ore with a composition of 180 kg NaClO3 and 180 kg water/ton ore reached a temperature of 470 °C at a microwave power of 400 watts for 30 minutes. Total oxidized sulfur reached 90.6%, while only 10.4 % of the sulfur was released, and chlorine release was 49.5%. In addition, water leaching was conducted to investigate the extraction rate of metals after roasting. The results showed that the water leaching extraction of Cu, Zn, Pb, and Fe reached 84.3%, 97.6%, 22.8%, and 8.4%, respectively. Applying microwaves with appropriate concentrations of additives and water resulted in high oxidation of sulfide minerals (>90%) and low sulfur emissions in roasting refractory gold ore with relatively low power, temperature, and time. Moreover, leaching this roasted gold ore resulted in gold extraction of 92.5%; however, leaching of refractory gold without pretreatment resulted in gold extraction of only 47.5%.

Biodegradation and sorption of nutrients and endocrine disruptors in a novel concrete-based substrate in vertical-flow constructed wetlands

Removing phosphorus and endocrine-disruptors (EDC) is still challenging for low-cost sewage treatment systems. This study investigated the efficiency of three vertical-flow constructed wetlands (VFCW) vegetated with Eichhornia crassipes onto red clay (CW-RC), autoclaved aerated concrete (CW-AC), and composite from the chemical activation of autoclaved aerated concrete with white cement (CW-AAC) in the removal of organic matter, nutrients, and estrone, 17β-estradiol, and 17α-ethinylestradiol. The novelty aspect of this study is related to selecting these clay and cementitious-based materials in removing endocrine disruptors and nutrients in VFCW. The subsurface VFCW were operated in sequencing-batch mode (cycles of 48-48-72 h), treating synthetic wastewater for 308 days. The operation consisted of Stages I and II, different by adding EDC in Stage II. The presence of EDC increased the competition for dissolved oxygen (DO) and reduced the active sites available for adsorption, diminishing the removal efficiencies of TKN and TAN and total phosphorus in the systems. CW-RC showed a significant increase in COD removal from 65% to 91%, while CW-AC and CW-AAC maintained stable COD removal (84%–82% and 78%–81%, respectively). Overall, the substrates proved effective in removing EDC, with CW-AC and CW-AAC achieving >60% of removal. Bacteria Candidatus Brocadia and Candidatus Jettenia, responsible for carrying out the Anammox process, were identified in assessing the microbial community structure. According to the mass balance analysis, adsorption is the main mechanism for removing TP in CW-AC and CW-AAC, while other losses were predominant in CW-RC. Conversely, for TN removal, the adsorption is more representative in CW-RC, and the different metabolic routes of microorganisms, biofilm assimilation, and partial ammonia volatilization in CW-AC and CW-AAC. The results suggest that the composite AAC is the most suitable material for enhancing the simultaneous removal of organic matter, nutrients, and EDC in VFCW under the evaluated operational conditions.

Multiphase-solid fluid inclusions in HP-LT eclogite facies rock (Zavkhan Terrane, Western Mongolia): evidence for the evolution from saline to hypersaline fluids during metamorphism in subduction zone

Fluid inclusions in high- and ultrahigh-pressure metamorphic rocks provide direct information on the composition of the fluids that evolved during metamorphism and fluid-rock interactions in deep subduction zones. We investigate the fluid inclusions in the Khungui eclogite of the Zavkhan Terrane, Central Asian Orogenic Belt. Fluid inclusions are observed in garnet and quartz in the eclogite samples that underwent metamorphism during subduction. The primary fluid inclusions in quartz are composed of liquid and vapor with high salinities (15.7–16.4 wt.% NaCl eq.), whereas the secondary fluid inclusions in quartz are classified as: relatively high salinity (Type I:12.5–16.3 wt.% NaCl eq.) and low salinity (Type II:6.7–10.6 wt.% NaCl eq.). The garnet shows compositional zoning from Ca-poor cores to Ca-rich rims, and the rims that grew during the eclogite-stage metamorphism (2.1–2.2 GPa at 580–610 °C) preferentially contain numerous primary fluid inclusions. The primary fluid inclusions in garnet are commonly bi-phases (liquid and vapor); however, some are multiphase-solid fluid inclusions composed of fluids (liquid and vapor) and combinations of several minerals (halite, quartz, apatite, calcite, biotite, chlorite, and actinolite). Bi-phase fluid inclusions preferentially occur in the inner parts of the Ca-rich garnet rim, whereas multiphase-solid fluid inclusions occur along the margins of the Ca-rich rim. We hypothesize that the multiphase-solid fluid inclusions are formed via interactions between trapped fluids, trapped minerals, and the host garnet during exhumation. By combination of FIB–SEM and synchrotron X-ray CT analyses, the detailed occurrences, volumes, and compositions of the solid phases in the fluid inclusion was analyzed. We then conduct mass balance analysis to reconstruct accurate fluid compositions using data from the FIB–SEM and synchrotron X-ray CT images of the multiphase-solid fluid inclusion. The results of these analyses reveal that (1) fluid changed from an H2O-dominated saline fluid (13–16 wt. % NaCl eq.) at the prograde to the earlier eclogite stage to H2O–CO2-dominated hypersaline fluid at later eclogite stage (~ 32 wt. % NaCl eq., 7.3 wt. % CO2 and ~ 19 molal dissolved cations); (2) a variety of mineral assemblages in multiphase-solid fluid inclusions are produced by post-entrapment reactions between the trapped hypersaline fluid, trapped minerals and the fluid host mineral. The evolution of fluids from saline to hypersaline during the eclogite facies stage is probably caused by the formation of hydrous minerals (i.e., barroisite) under a near-closed system.

Calcium peroxide mediated sustainable microalgal-bacterial consortium system: Role and significance of configured anaerobic fermentation

Microalgal-bacterial consortium (MBC) is an effective way to meet increasingly stringent standards in wastewater treatment, with advantages in nutrient removal, resource recovery, and energy conservation. The efficient and stable operation of the MBC sewage treatment system is generally limited by the insufficient and unstable carbon source in the influent. In this study, a calcium peroxide-mediated anaerobic fermenter was configured to transfer the MBC sludge into the preferred carbon source, short-chain fatty acids (SCFAs) in-situ, to alleviate the limitations. Experimental results showed that after 4-day 0.15 g/g VS calcium peroxide mediated anaerobic fermentation, the production of SCFAs and the proportion of acetic acid reached 514.8 mg COD/g VS and 59 %, respectively. Scanning electron microscopy, COD mass balance analysis, and lactate dehydrogenase assays jointly showed that calcium peroxide effectively promoted the breakdown of MBC sludge cells, which led to the release of large amounts of organic matter and could be attributed to the released OH–, ·OH and ·O2– from calcium peroxide, thereby providing more bioavailable substrates for SCFAs production. Microbial community analysis indicated that the anaerobes associated with hydrolysis and degradation of refractory organic matters were enriched in the mediated fermenter and had positive correlation with SCFAs production. Using such fermentation liquid as an additional carbon source for influent sewage, the MBC process performance was significantly promoted, with phosphorus and COD removal and sludge settleability reaching 84.7 %, 96.1 %, and 33 %, respectively. Configuring calcium peroxide-mediated anaerobic fermentation may thus become a sustainable strategy to strengthen the MBC sewage treatment system, thus providing new ideas for wastewater treatment to reduce inputs and improve performance.

Techno-economic analysis of developing miscanthus biorefinery for the production of platform chemicals and renewable resins

Biorefining to produce chemical materials is a viable path to a renewable and sustainable future. The energy crop Miscanthus is grown with high yield and low cost. In this study, platform chemicals (acetic acid, glycolaldehyde, and acetol) and novolac resins were produced using Miscanthus at a baseline plant capacity of 15 t/h. The profitability of different biochar applications (soil amendment, heat supply, and activated carbon) was investigated by mass balance and energy consumption analysis and economic assessment. The heat supply scenario had the best profitability with an internal rate of return (IRR), payback period, levelized cost, and minimum selling price of 24.5%, 4.32 years, CNY 8,480/t, and CNY 10,840/t. Sensitivity analysis showed that IRR was most sensitive to resin price, plant capacity, and capital costs. The minimum plant capacity with an IRR over 25% was 25 t/h. Monte-Carlo simulation results showed a low investment risk for soil amendment and heat supply scenarios.

A mass-balance approach for predicting lake phosphorus concentrations as a function of external phosphorus loading: Application to the Lake St. Clair – Lake Erie System (Canada – USA)

Abstract A mass balance model is presented that links the total phosphorus concentration in lakes to the water residence time, Rw (lake volume divided by the annual water inflow) and the total phosphorus residence time, Rp (average standing stock of lake total phosphorous divided by the external annual total phosphorus input). Following a change in the external load, the lake total phosphorus concentration asymptotically approaches a new value that depends on the Rp:Rw ratio, with the rate of approach controlled by Rp. We applied this approach to a recent reanalysis of the water and total phosphorus budgets of the Lake Erie system of the Laurentian Great Lakes for the 2003-2016 period. We generated load–response relationships and response matrices that relate the steady state total phosphorus concentrations to external total phosphorus loads, for the whole Lake Erie system and for the individual basins (Lake St. Clair, western basin, central basin, eastern basin) and connecting channels (St. Clair River, Detroit River). These relationships and matrices provide a simple but robust framework to gauge the potential response of total phosphorus concentrations to total phosphorus load reductions, such as the 40% reduction proposed for Lake Erie under the Canada-United States Great Lakes Water Quality Agreement. The mass balance analysis further highlights the importance of inter-basin total phosphorus transfers. For example, around 70% of the total phosphorus concentration in the eastern basin is contributed by inflow from the central basin. Consequently, total phosphorus load abatements in watersheds upstream of the eastern basin, rather than in the direct watershed itself, will have the greatest impact on the eastern basin's concentration. Overall, our results illustrate how simple mass balance calculations can provide useful guidance to efforts to manage phosphorus enrichment of lakes.