Purification of inorganic nitrogen from the mariculture tail water by anaerobic/anoxic/oxic (A2O) process.

This study aims to address the suboptimal performance of conventional denitrifying strains in treating mariculture tail water (MTW) containing inorganic nitrogen (IN). The concentration of inorganic nitrogen in the mariculture tail water is about 5-20 mg·L-1. A biofilm treatment process was developed and evaluated using an anoxic-anoxic-aerobic biofilter composite system inoculated with the denitrifying strain Meyerozyma guilliermondii Y8. The removal effect of total nitrogen (TN), IN, and Chemical Oxygen Demand (CODMn) from MTW was investigated. The results indicate that the A2O composite biological filter has excellent pollutant removal efficiency within 25 days of operation, after the acclimation of the denitrifying microorganisms. The initial concentrations of TN, IN, and CODMn ranged between 10.24 and 12.89 mg·L-1, 7.84-10.49 mg·L-1, and 9.44-11.52 mg·L-1, respectively, and the removal rates of these indexes reached 38-68 %, 45-70 %, and 55-70 %, respectively. The experiments with different hydraulic retention times (HRT = 6 h, 8 h, 10 h) demonstrated that longer HRT was more conducive to the removal of inorganic nitrogen. Moreover, scanning electron microscopy observations revealed that the target strain successfully grew and attached to the filler in large quantities. The findings of this study provide practical guidance for the development of efficient biofilm processes for the treatment of MTW.

Pilot composite tubular bioreactor for outdoor photo-fermentation hydrogen production: From batch to continuous operation.

A novel 70 L composite tubular photo-bioreactor was constructed, and its photo-fermentation hydrogen production characteristics of batch and continuous modes were investigated with glucose as the substrate in an outdoor environment. In the batch fermentation stage, the hydrogen production rate peaked at 37.6 mL H2/(L·h) accompanied by a high hydrogen yield of 7 mol H2/mol glucose. The daytime light conversion efficiency is 4 %, with 37 % of light energy from the sun. An optimal hydraulic retention time of 5 d was identified during continuous photo-fermentation. Under this condition, the stability of the cell concentration is maintained and more electrons can be driven to the hydrogen generation pathway while attaining a hydrogen production rate of 20.7 ± 0.9 mL H2/(L·h). The changes of biomass, volatile fatty acids concentration and ion concentration during fermentation were analyzed. Continuous hydrogen production by composite tubular photo-bioreactor offers new ideas for the large-scale deployment of photobiological hydrogen production.

Algal-bacterial shortcut nitrogen removal model with seasonal light variations.

The algal-bacterial shortcut nitrogen removal (ABSNR) process can be used to treat high ammonia strength wastewaters without external aeration. However, prior algal-bacterial SNR studies have been conducted under fixed light/dark periods that were not representative of natural light conditions. In this study, laboratory-scale photo-sequencing batch reactors (PSBRs) were used to treat anaerobic digester sidestream under varying light intensities that mimicked summer and winter conditions in Tampa, FL, USA. A dynamic mathematical model was developed for the ABSNR process, which was calibrated and validated using data sets from the laboratory PSBRs. The model elucidated the dynamics of algal and bacterial biomass growth under natural illumination conditions as well as transformation processes for nitrogen species, oxygen, organic and inorganic carbon. A full-scale PSBR with a 1.2 m depth, a 6-day hydraulic retention time (HRT) and a 10-day solids retention time (SRT) was simulated for treatment of anaerobic digester sidestream. The full-scale PSBR could achieve >90% ammonia removal, significantly reducing the nitrogen load to the mainstream wastewater treatment plant (WWTP). The dynamic simulation showed that ABSNR process can help wastewater treatment facilities meet stringent nitrogen removal standards with low energy inputs.

Spatial monitoring of hydrolysis in a plug-flow bioreactor: a support for flexible operation?

Hydrolysis at changing hydraulic retention time, recirculation, bedding straw content in the feed, bioaugmentation and the impact of those changes on gradient formation in the liquid phase in plug-flow reactors (PFRs) was examined. The pH-value, conductivity and oxidation-reduction potential (ORP) were monitored at three spots along the PFRs to study potential correlations to process performance during a total process time of 123 weeks. The on-line monitoring showed good correlations to acidogenesis: namely, the pH and ORP to the acidification, to butyric (and lactic) acid concentration and to the acid yield. The ORP (measured at the inlet) showed the most stable correlation to acidogenesis under dynamic operation, while the conductivity (at the outlet) correlated to the acid concentration in dependence on the feedstock. Multiple measurement spots as used in this study allow to gain more information about acidogenic fermentation than a single spot, simplifying process control and automation attempts with recalcitrant feedstock.

Downflow sponge biofilm reactors for polluted raw water treatment: Performance optimisation, kinetics, and microbial community.

Water outages caused by elevated ammonium (NH4+-N) levels are a prevalent problem faced by conventional raw water treatment plants in developing countries. A treatment solution requires a short hydraulic retention time (HRT) to overcome nitrification rate limitation in oligotrophic conditions. In this study, the performance of polluted raw water treatment using a green downflow sponge biofilm (DSB) technology was evaluated. We operated two DSB reactors, DSB-1 and DSB-2 under different NH4+-N concentration ranges (DSB-1: 3.2-5.0 mg L-1; DSB-2: 1.7-2.6 mg L-1) over 360 days and monitored their performance under short HRT (60 min, 30 min, 20 min, and 15 min). The experimental results revealed vertical segregation of organic removal in the upper reactor depths and nitrification in the lower depths. Under the shortest HRT of 15 min, both DSB reactors achieved stable NH4+-N and chemical oxygen demand removal (≥95%) and produced minimal effluent nitrite (NO2--N). DSB system could facilitate complete NH4+-N oxidation to nitrate (NO3--N) without external aeration energy requirement. The 16S rRNA sequencing data revealed that nitrifying bacteria Nitrosomonas and Nitrospira in the reactor were stratified. Putative comammox bacteria with high ammonia affinity was successfully enriched in DSB-2 operating at a lower NH4+-N loading rate, which is advantageous in oligotrophic treatment. This study suggests that a high hydraulic rate DSB system with efficient ammonia removal could incorporate ammonia treatment capability into polluted raw water treatment process and ensure safe water supply in many developing countries.

Rapid establishment of municipal sewage partial denitrification-anammox for nitrogen removal through inoculation with side-stream anammox biofilm without domestication.

Mainstream partial denitrification anammox was achieved through inoculation of side-stream mature partial nitritation anammox biofilm without domestication. The contribution of anammox to nitrogen removal was 29.4 %. Moreover, prolonging anoxic hydraulic retention time and introducing side-stream nitrite under different carbon/nitrogen ratios enriched anammox bacteria. The abundance of anammox bacteria increased by âˆ¼ 10 times ((2.19 ± 0.17) × 1012 copies gene / g dry sludge) with a total relative abundance of 18.51 %. During 258 days of operation, the contribution of anammox to nitrogen removal gradually increased to 68.8 %. The total nitrogen in the effluent decreased to 8.84 mg/L with a total nitrogen removal efficiency of 76.4 % under a carbon/nitrogen ratio of 3. This paper proposes a novel way to rapidly achieve mainstream partial denitrification anammox via inoculation with side-stream mature partial nitritation anammox biofilm. This method achieves advanced nitrogen removal from municipal wastewater, even under low carbon/nitrogen ratios.

Enhanced reduction of sulfate by iron-carbon microelectrolysis: interaction mechanism between microelectrolysis and microorganisms.

Sulfate wastewater has a wide range of sources and greatly harms water, soil, and plants. Iron-carbon microelectrolysis (IC-ME) is a potentially sustainable strategy to improve the treatment of sulfate (SO42-) wastewater by sulfate-reducing bacteria (SRB). In this study, an iron-carbon mixed micro-electrolysis bioreactor (R1), iron-carbon layered bioreactor (R2), activated carbon bioreactor (R3), and scrap iron filing bioreactor (R4) were constructed by up-flow column experimental device. The performance and mechanism of removing high-concentration sulfate wastewater under different sulfate concentrations, hydraulic retention times (HRT), and chemical oxygen demand (COD)/SO42- were discussed. The results show that the iron-carbon microelectrolysis-enhanced SRB technology can remove high-concentration sulfate wastewater, and the system can still operate normally at low pH. In the high hydraulic loading stage (HRT = 12 h, COD/SO42- = 1.4), the SO42- removal rate of the R1 reactor reached 98.08%, and the ORP value was stable between - 350 and - 450 mV, providing a good ORP environment for SRB. When HRT = 12 h and influent COD/SO42- = 1.4, the R1 reactor sulfate removal rate reached 96.7%. When the influent COD/SO42- = 0.7, the sulfate removal rate was 52.9%, higher than the control group. Biological community analysis showed that the abundance of SRB in the R1 reactor was higher than that in the other three groups, indicating that the IC-ME bioreactor could promote the enrichment of SRB and improve its population competitive advantage. It can be seen that the synergistic effect between IC-ME and biology plays a vital role in the treatment of high-concentration sulfate wastewater and improves the biodegradability of sulfate. It is a promising process for treating high-concentration sulfate wastewater.

Domestic wastewater treatment by Pistia stratiotes in constructed wetland.

The objective of the study was to evaluate the performance of Pistia stratiotes for treatment of domestic wastewater in a free surface water flow constructed wetland. The objective of the study was to evaluate contaminants removal efficiency of the constructed wetland vegetated with P. stratiotes in treatment of domestic wastewater against Hydraulic retention time (HRT) of 10, 20 and 30 days was investigated. This asks for newer and efficient low-cost nature-based water treatment system which along with cost takes into consideration the sustainability of the ecosystem. Five constructed wetland setups improved the wastewater quality and purify it significantly by reducing the TDS by 83%, TSS by 82%, BOD by 82%, COD by 81%, Chloride by 80%, Sulfate by 77%, NH3 by 84% and Total Oil and Grease by 74%. There was an increase in pH of about 11.9%. Color and odor of wastewater was also improved significantly and effectively. It was observed that 30 days' HRT was optimum for the treatment of domestic wastewater. The final effluent was found to be suitable as per national environmental quality standards and recycled for watering plants and crop irrigation but not for drinking purposes. The treatment in constructed wetland system was found to be economical, as the cost of construction only was involved and operational and maintenance cost very minimal. Even this research was conducted on the sole purpose of commuting the efficiency of pollutant removal in short span time.

Performance evaluation of Anaerobic-Aerobic Hybrid Baffled Reactor Coupled with an Anaerobic Filter treating Landfill Leachate.

The Anaerobic Baffled Reactor (ABR) is an effective solution for landfill leachate treatment using an anaerobic fermentation process, which helps to reduce operating costs and sludge volume. To better understand the biological, chemical, and physical processes involved, especially when combining the ABR with an aerobic component, the study aimed to investigate the performance of an Anaerobic-Aerobic Hybrid Baffled Reactor (AABR) that includes an Anaerobic Filter (AF) for treating landfill leachate. This research utilized two glass reactors. The first reactor, designated as AABR-AF, consisted of six independent rectangular glass chambers arranged side by side. The third and sixth chamber designed for aerobic treatment and AF, respectively. The second reactor was used as a control reactor and did not include any aerobic chamber. The highest Removal Efficiencies (REs) for turbidity, COD, BOD, TP, TKN, nitrate, TOC, and TSS in the AABR-AF and ABR-AF were found to be (65.4% and 56.3%), (98.3% and 94.1%), (98.1% and 93.2%), (86.4% and 65%), (89.2% and 76.7%), (81.2% and 64.4%), (88.2% and 79.4%), and (72.4% and 68.5%), respectively. These optimal REs were achieved at an HRT of 48 h and an OLR of 10 kg/m3.d. Also, the highest and the lowest REs in Heavy Metals (HMs) were 89.57% for manganese in AABR-AF and 6.59% for nickel in ABR-AF, in an OLR of 10 kg/m3.d, respectively. The effective removal of Organic Matters (OMs) from landfill leachate using the AABR-AF and ABR-AF was found to be strongly influenced by HRT and OLR. The AABR-AF configuration, featuring a single aerobic chamber in the reactor, exhibited a higher efficiency in removing OMs compared to the ABR-AF configuration.

Optimizing the algae-bacteria biofilm reactor for imidacloprid wastewater treatment: An evaluation of hydraulic retention times for enhanced efficiency and energy savings.

Recent observations have highlighted the rapidly growing prevalence of emerging contaminants such as Imidacloprid (IMI) within our environment. These insecticidal pollutants, coexisting with more traditional contaminants, have become predominant in aquatic systems, posing risks to both human and ecological well-being. Among the various wastewater treatment approaches tested, biofilm reactors are currently gaining prominence. In this study, we employed an Algae-Bacteria Biofilm Reactor (ABBR) to concurrently address both conventional and emergent contaminants, specifically IMI, over an extended timeframe. Following a 60-day assessment, the ABBR consistently demonstrated removal efficiencies exceeding 85% for total dissolved nitrogen, ammonia nitrogen, and total dissolved phosphorus, and also achieved removal efficacy for the soluble chemical oxygen demand (sCOD). Despite the removal efficiency of IMI (with initial concentration is 1.0 mg/L) in ABBR showed a gradual decline over the extended period, it remained consistently effective over 50% due to the microalgae-mediated free radical reactions, indicating the ABBR's sustained efficiency in long-duration operations. Additionally, applying some non-conventional modifications, like aeration removal and reducing light exposure, demonstrated minimal impact on the reactor's pollutant removal efficiencies, achieving comparable results to the control group (which utilized aeration with a 14:10 light/dark ratio), 0.92 kW h/L/d of electricity can be saved economically, which accentuated the potential for energy conservation. An in-depth analysis of the treated effluents from the ABBRs, using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) technique, uncovered four potential transformation pathways for IMI. Overall, our findings suggest that these optimized processes did not influence the transformation products of IMI, thereby reaffirming the viability of our proposed optimization.

Effects of bed depths and the ratio of aerobic to anaerobic zone on the performance of horizontal subsurface flow macrophyte-assisted high-rate vermifilters treating synthetic brewery wastewater.

Effects of total vermibed depth, as well as the ratio of aerobic (the unsubmerged) to anaerobic (the submerged) zone on the performance of the horizontal subsurface flow macrophyte-assisted vermifilters (HSSF-MAVFs) treating synthetic brewery wastewater at a higher hydraulic loading rate (HLR), were investigated for the first time. Results showed that the HSSF-MAVF with a 50 cm total and 18 cm submerged vermibed depth yielded the optimum removal of the pollutants, ensuring a (91.2 ± 1.7)%, (81.8 ± 1.9)%, (67.4 ± 3.9)%, and (63.1 ± 2.3)% removal of chemical oxygen demand (COD), ammonium N (NH4 + -N), total N (TN), and organic N, respectively, whereas there was an increase of (142 ± 6.3)% in the effluent nitrate-N (NO3 - -N) than that in the influent. At the optimum condition, the effluent concentrations of all the pollutants including COD, NH4 + -N, NO3 - -N, TN, and organic N were well below the surface water discharge standards specified by the Central Pollution Control Board (CPCB), and thus, the effluent of the HSSF-MAVF could be safely discharged into the surface water bodies. PRACTITIONER POINTS: Total vermibed depth of HSSF-MAVFs was optimized for organic and nitrogen removal. HSSF-MAVFs were subjected to the higher HLR of synthetic brewery wastewater. Removal of COD and NH4 + -N was decreased with the increase in submerged bed depth. Removal of organic N and TN was increased with the increase in submerged bed depth. Total/unsubmerged bed depth had a positive impact on the organic and N removal.

Developing a versatile tool for studying kinetics of Selenate-Se removal from aqueous solution using a chemostat bioreactor.

Understanding the impact of various parameters on the kinetics of dissolved selenium (Se) removal in bioreactors can be a challenging task, primarily due to the mass transfer limitations inherent in bioreactors employing attached growth configurations. This study successfully established a proof-of-concept for the efficient removal of Se from aqueous solutions using a chemostat bioreactor that relies solely on suspended growth. The research investigated the effect of selenate-Se feed concentrations under two distinct Se concentration conditions. One experiment was conducted at a considerably elevated concentration of 25 mg/L to impose stress on the system and evaluate its response. Another experiment replicated an environmentally relevant concentration of 1 mg/L, mirroring the typical Se concentrations in mine water. The bioreactor, featuring a working volume of 0.35 L, was operated as an anaerobic, fully mixed chemostat with hydraulic retention times (HRTs) ranging from 5 to 0.25 days. The outcomes revealed the chemostat's capacity to remove up to 25 mg/L of dissolved Se from water for all HRTs exceeding 1 day, under otherwise optimal conditions encompassing temperature, pH, and salinity. The research's significance lies in the development of a versatile tool designed to examine Se removal kinetics within a system devoid of mass transfer limitations. Furthermore, this study verified the ability of the bacterial consortium, obtained from a mine-influenced environment and enriched in the laboratory, to grow and sustain Se removal activities within a chemostat operating with HRTs as short as 1 day.

Methods for the separation of hydraulic retention time and solids retention time in the application of photosynthetic microorganisms in photobioreactors: a review.

Photosynthetic microorganisms have a wide range of biotechnical applications, through the application of their versatile metabolisms. However, their use in industry has been extremely limited to date, partially because of the additional complexities associated with their cultivation in comparison to other organisms. Strategies and developments in photobioreactors (PBRs) designed for their culture and applications are needed to drive the field forward. One particular area which bears examination is the use of strategies to separate solid- and hydraulic-residence times (SRT and HRT), to facilitate flow-through systems and continuous processing. The aim of this review is to discuss the various types of PBRs and methods which are currently demonstrated in the literature and industry, with a focus on the separation of HRT and SRT. The use of an efficient method of biomass retention in a PBR may be advantageous as it unlocks the option for continuous operation, which may improve efficiency, and improve economic feasibility of large-scale implementation of photosynthetic biocatalysts, especially where biomass is not the primary product. Due to the underexplored nature of the separation of HRT and SRT in reactors using photosynthetic microorganisms, limited literature is available regarding their performance, efficiencies, and potential issues. This review first introduces an overview into photosynthetic microorganisms cultivated and commonly exploited for use in biotechnological applications, with reference to bioreactor considerations specific to each organism. Following this, the existing technologies used for the separation of HRT and SRT in PBRs are explored. The respective advantages and disadvantages are discussed for each PBR design, which may inform an interested bioprocess engineer.

Insight into anammox granular system operation in wet/dry weather.

Effects of short hydraulic retention time (HRT) in wet weather and long HRT in dry weather on sludge properties, microbial community, and metabolomic of anammox granular system were studied. Results showed under equal nitrogen loading rate (0.4 kg N/(m3 · d)) conditions, an HRT of 4.41 h was beneficial for total nitrogen removal efficiency (78.9 %). The shorter the HRT, the lower the particle density (1.01±0.34 g/cm3), the lower the settling performance (1.18±0.28 cm/s), and the worse the biomass retention (1.04±0.18 g/L), but the higher the mechanical strength (85.22 Pa). Properly decreasing HRT could increase the permeability of anammox granules, ensuring their activity. Metabolomics analysis indicated that the activity of anaerobic ammonium oxidizing bacteria was promoted by stimulating the metabolic pathways of amino acids and glycerophospholipids. In summary, this research clarified the effect of wet/dry weather on anammox granular system and provided theoretical guidance for the application in engineering.

Deciphering the influencing mechanism of hydraulic retention time on purification performance of a mixotrophic system from the perspective of reaction kinetics.

At present, eutrophication is increasingly serious, so it is necessary to effectively reduce nitrogen and phosphorus in water bodies. In this study, a pyrite/polycaprolactone-based mixotrophic denitrification (PPMD) system using pyrite and polycaprolactone (PCL) as electron donors was developed and compared with pyrite-based autotrophic denitrification (PAD) system and PCL-based heterotrophic denitrification (PHD) system through continuous flow experiment. The removal efficiency of NO3--N (NRE) and PO43--P (PRE) and the contribution proportion of PAD in the PPMD system were significantly increased by prolonging hydraulic retention time (HRT, from 1 to 48 h). When HRT was equal to 24 h, the PPMD system conformed to the zero-order kinetic model, so NRE and PRE were mainly limited by the PAD process. When HRT was equal to 48 h, the PPMD system met the first-order kinetic model with NRE and PRE reaching 98.9 ± 1.1% and 91.8 ± 4.5%, respectively. When HRT = 48 h, the NRE and PRE by PAD system were 82.7 ± 9.1% and 88.5 ± 4.7%, respectively, but the effluent SO42- concentration was as high as 152.1 ± 13.7 mg/L (the influent SO42- concentration was 49.2 ± 3.3 mg/L); the NRE by PHD system was 98.5 ± 1.7%, but the PO43--P could not be removed ideally. The concentrations of NO3--N, total nitrogen, PO43--P, and SO42- in the PPMD system also showed distinct changes along the reactor column. In addition, the microbial diversity analysis showed that prolonging HRT (from 24 to 48 h) increased the abundance of autotrophic denitrifying microorganisms in the PPMD system, ultimately increasing the contribution proportion of PAD.

Phytoplankton functional groups as indicators of environmental changes in weir and non-weir sections of the lower Nakdong River, Republic of Korea.

The Nakdong River underwent water impoundment after eight weirs were constructed as part of South Korea's Four Major River Restoration Project from 2009 to 2012. In this study, we aimed to confirm whether the assemblage of phytoplankton based on phytoplankton functional groups (PFGs), could indicate environmental changes in the weir section (WS) and non-weir section (NWS) of the lower Nakdong River after the construction of the weir. Thus, we examined the relationships between PFGs and gradients in environmental drivers, such as physicochemical, meteorological, and hydrological variables. Environmental gradients were observed between the WS and NWS in dissolved oxygen (DO), electric conductivity (EC), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), dissolved total nitrogen (DTN), dissolved total phosphorus (DTP), ammonia nitrogen (NH3-N), nitrate nitrogen (NO3-N), and phosphorus (PO4-P), which were relatively higher in the WS. Seventeen PFGs were identified (A, B, C, D, E, F, G, H1, J, LM, LO, MP, P, T, W1, X1, and X2). Additionally, the LM and P groups, preferring an enriched lentic system more than other groups, were found to be the dominant PFGs that led the succession of assemblages. Traditional nutrients (N, P) and organic pollutants (BOD, COD) primarily affected the autochthonous growth of the most dominant PFGs in the WS as HRT (hydraulic retention time) increased. Furthermore, the hydrological variables associated with meteorological conditions have a synergistic effect on the composition of the major PFGs and chemical and physical variables in the WS. In other words, the WS may be a new source of inoculum that primarily determines the occurrence and maintenance of phytoplankton in the immediate downstream region (NWS). In particular, group LM (mainly potentially toxic Microcystis) developing in the upper weir impoundment is transported downstream, resulting in a high inoculation effect on further growth in the NWS during the summer monsoon season.

Regulation of hydraulic retention time on caproic acid production via two-phase anaerobic fermentation of Chinese cabbage waste with autopoietic electron donors.

The effects of hydraulic retention time (HRT) on the performance of two-phase anaerobic fermentation for caproic acid production from Chinese cabbage waste (CCW) were investigated. In the electron donor phase, yeast was inoculated to achieve efficient autopoietic ethanol, providing electron donors for the chain elongation process. Shorter HRT led to drastic fluctuations in microorganisms, thus resulting in lower acid yields at HRT of 6 days. At HRT of 10 days, the balanced collaboration of various key bacteria avoided the accumulation of intermediate by-products, and the caproic acid production reached 4660 mg COD/L, which was 119.5% and 154.8% higher than that at HRTs of 6 and 14 days, respectively. At HRT of 14 days, the low ethanol loading rate resulted in ethanol excessive-oxidation to acetic acid. Acetic acid accounted for 41.5% of the total product, while the selectivity of caproic acid was only 15.3%. The main contributor to the production process of caproic acid was Caproiciproducens, while the Ruminalococcaceae also played a role in the process. This study provided a theoretical basis for the efficient production of caproic acid through continuous fermentation with autopoietic electron donors.

Impact of cascade reservoirs on nutrients transported downstream and regulation method based on hydraulic retention time.

Cascade reservoirs construction has modified the nutrients dynamics and biogeochemical cycles, consequently affecting the composition and productivity of river ecosystems. The Jinsha River, as the predominant contributor to runoff, suspended sediment (SS), and nutrients production within the Yangtze River, is a typical cascade reservoir region with unclear transport patterns and retention mechanisms of nutrients (nitrogen and phosphorus). Furthermore, how to regulate nutrients delivery in the cascade reservoirs region is also an urgent issue for basin water environment study. Therefore, we monitored monthly variations in nitrogen and phosphorus concentrations from November 2021 to October 2022 in the cascade reservoirs of the Jinsha River. The results indicated that the concentrations and fluxes of total phosphorus (TP) and particulate phosphorus (PP) decreased along the cascade of reservoirs, primarily due to PP deposited with SS, while opposing trends for total nitrogen (TN) and dissolved total nitrogen (DTN), which might be the consequences of human inputs and the increase of dissolved inorganic nitrogen discharged from the bottom of the reservoirs. Moreover, the positive average annual retention ratios for TP and PP were 10% and 16%, respectively, in contrast to the negative averages of -8 % for TN and -11% for particulate nitrogen (PN). The variability in runoff-sediment and hydraulic retention time (HRT) of cascade reservoirs played crucial roles in the retention of TP and PP. A regulatory threshold of HRT = 5.3 days in the flood season was obtained for controlling the balance of TP based on the stronger relationship between HRT and TP retention ratio. Consequently, the HRT of these reservoirs could be managed to control nutrients delivery, which was of particular significance for basin government institutions. This study enhances our comprehension of how cascade reservoirs influence the distribution and transport patterns of nutrients, offering a fresh perspective on nutrients delivery regulation.

Changes in environmental and engineered conditions alter the plasma membrane lipidome of fractured shale bacteria.

IMPORTANCE: Microorganisms inadvertently introduced into the shale reservoir during fracturing face multiple stressors including brine-level salinities and starvation. However, some anaerobic halotolerant bacteria adapt and persist for long periods of time. They produce hydrogen sulfide, which sours the reservoir and corrodes engineering infrastructure. In addition, they form biofilms on rock matrices, which decrease shale permeability and clog fracture networks. These reduce well productivity and increase extraction costs. Under stress, microbes remodel their plasma membrane to optimize its roles in protection and mediating cellular processes such as signaling, transport, and energy metabolism. Hence, by observing changes in the membrane lipidome of model shale bacteria, Halanaerobium congolense WG10, and mixed consortia enriched from produced fluids under varying subsurface conditions and growth modes, we provide insight that advances our knowledge of the fractured shale biosystem. We also offer data-driven recommendations for improving biocontrol efficacy and the efficiency of energy recovery from unconventional formations.

Optimization of semi-continuous dry anaerobic digestion process and biogas yield of dry yellow corn straw: Based on "gradient anaerobic digestion reactor".

In China, the problem of low biogas yield of traditional biogas projects has become increasingly prominent. This study investigated the effects of different hydraulic retention times (HRTs) on the biogas production efficiency and microbial community under pilot conditions. The results show that the "Gradient anaerobic digestion reactor" can stably carry out semi-continuous dry anaerobic digestion and improve biogas yield. The highest volatile solids (VS) biogas yield (413.73 L/kg VS and 221.61 L CH4/kg VS) and VS degradation rate (48.41%) were observed at an HRT of 25 days. When the HRT was 15 days, the volumetric biogas yield was the highest (2.73 L/L/d, 1.43 L CH4/L/d), but the VS biogas yield and degradation rate were significantly decreased. Microbial analysis showed that HRT significantly affected microbial community. It provides basic data support for the development of a new anaerobic digestion process and the practical application of the straw biogas project in China.