Initial pH Levels Research Articles

Effect of Different Initial Fermentation pH on Exopolysaccharides Produced by Pseudoalteromonas agarivorans Hao 2018 and Identification of Key Genes Involved in Exopolysaccharide Synthesis via Transcriptome Analysis.

Exopolysaccharides (EPSs) are carbohydrate polymers produced and secreted by microorganisms. In a changing marine environment, EPS secretion can reduce damage from external environmental disturbances to microorganisms. Meanwhile, EPSs have promising application prospects in the fields of food, cosmetics, and pharmaceuticals. Changes in external environmental pH have been shown to affect the synthesis of EPSs in microorganisms. In this study, we analyzed the effects of different initial fermentation pHs on the production, monosaccharide composition, and antioxidant activity of the EPSs of Pseudoalteromonas agarivorans Hao 2018. In addition, the transcriptome sequence of P. agarivorans Hao 2018 under different initial fermentation pH levels was determined. GO and KEGG analyses showed that the differentially expressed genes were concentrated in the two-component regulatory system and bacterial chemotaxis pathways. We further identified the expression of key genes involved in EPS synthesis during pH changes. In particular, the expression of genes encoding the glucose/galactose MFS transporter, phosphomannomutase, and mannose-1-phosphate guanylyltransferase was upregulated when the environmental pH increased, thus promoting EPS synthesis. This study not only contributes to elucidating the environmental adaptation mechanisms of P. agarivorans, but also provides important theoretical guidance for the directed development of new products using biologically active polysaccharides.

Influence of Selected Restorative Materials on the Environmental pH: In Vitro Comparative Study

In dental caries treatment, it is worth using such restorative materials that may limit plaque accumulation. The pH of the filling seems to be an important factor affecting the potential bacterial colonisation. Our study aimed to assess how selected restorative materials influence the environmental pH. A total of 150 specimens (30 of each: Ketac Molar, Riva LC, Riva SC, Filtek Bulk Fill, and Evetric) were placed in 100 sterile hermetic polyethene containers with saline and stored in 37 °C. The pH of each sample was measured using the electrode Halo HI13302 (Hanna Instruments, Poland) at specific points in time for 15 days. The initial pH levels were significantly lower for glass ionomer cements (3.9–4.7) compared to composites (5.9–6.0). With time, the pH increased for samples with glass ionomer cements (by nearly 1.5), whereas it decreased for samples with composites (maximally by 0.8). In the end, all materials were in the pH range between 5.3 and 6.0. The highest final pH was obtained with Ketac Molar at about 5.9. Double samples had lower pH values than single samples, irrespective of the type of material. In conclusion, immediately after application, restorative materials decreased the environmental pH, especially light-cured glass ionomer cements. For glass ionomers, within two weeks, the pH increased to levels comparable with composites.

Flow cytometric analysis reveals culture condition dependent variations in phenotypic heterogeneity of Limosilactobacillus reuteri

Optimisation of cultivation conditions in the industrial production of probiotics is crucial to reach a high-quality product with retained probiotic functionality. Flow cytometry-based descriptors of bacterial morphology may be used as markers to estimate physiological fitness during cultivation, and can be applied for online monitoring to avoid suboptimal growth. In the current study, the effects of temperature, initial pH and oxygen levels on cell growth and cell size distributions of Limosilactobacillus reuteri DSM 17938 were measured using multivariate flow cytometry. A pleomorphic behaviour was evident from the measurements of light scatter and pulse width distributions. A pattern of high growth yielding smaller cells and less heterogeneous populations could be observed. Analysis of pulse width distributions revealed significant morphological heterogeneities within the bacterial cell population under non-optimal growth conditions, and pointed towards low temperature, high initial pH, and high oxygen levels all being triggers for changes in morphology towards cell chain formation. However, cell size did not correlate to survivability after freeze-thaw or freeze-drying stress, indicating that it is not a key determinant for physical stress tolerance. The fact that L. reuteri morphology varies depending on cultivation conditions suggests that it can be used as marker for estimating physiological fitness and responses to its environment.

Chemical and Antioxidant Activity Changes in Philippine Green Mussel (Perna viridis) during Fermentation at Varying Salt Concentrations

Green mussel (Perna viridis) is an extensively cultured bivalve species in the Philippines and a cheap source of valuable nutrients such as essential amino acids and minerals. Experimental samples were prepared by mixing salt to varying mussel meat ratios (1:3, 1:5, 1:7, and 1:9) which were assessed for changes in pH, degree of hydrolysis, and antioxidant activities during fermentation for 30 d. The pH levels in treatments 1:3, 1:5, and 1:7 decreased to low-acid levels (< pH 4.6) as fermentation progressed. Meanwhile, treatment 1:9 did not significantly change from its initial pH level with a slight decrease noted during 15 d but significantly increased at slightly neutral pH level (at 7.22) on 30 d. Formaldehyde nitrogen (formol-N) and the simultaneous formation of ammonia-N significantly increased (p < 0.05) with prolonged fermentation time but were more pronounced in 1:7 and 1:9 treatments. The gradual increase in pH and formol-N in treatments 1:3 and 1:5 could be due to the high salt content at 23.63 ± 0.29 %, and 19.48 ± 0.88 %, respectively, which could have slowed down proteolytic enzyme activity. However, continuous increase in ammonia-N in treatment 1:9 significantly reduced (p < 0.05) amino-N content which lowers the nutritional quality of fermented products. The development of antioxidant activities such as 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity, ferric reducing antioxidant power (FRAP), and total phenol content (TPC) as gallic acid equivalent (GAE) was highest in treatments 1:7 and 1:9. These findings could be attributed to the increasing degree of protein breakdown producing substances and reaction products with increased bioactivity. This is also supported by the significant positive linear correlation between formol-N and antioxidant system assays (DPPH, FRAP, and TPC) (p < 0.01)

Preparation of microbial dust suppressant and its application in coal dust suppression

To promote the application of microbially induced carbonate precipitation (MICP) technology for coal dust suppression, two urease-producing bacteria (SZS1-3 and SZS1-5) in a coal mine soil were screened. 16 s rDNA sequencing of these bacteria indicated sequences similar to those of Acinetobacter guillouiae CIP 63.46 and Staphylococcus caprae ATCC 35538, respectively. Strains SZS1-3 and SZS1-5 had their largest urease activity at the initial urea concentration of 0.5 mol/L, under slightly alkaline (pH = 9) and neutral (pH = 7) initial pH levels, respectively. Their final mineralized products were vaterite-type and calcite-type calcium carbonate. Although dust suppression results indicated that both bacteria can effectively bind coal dust particles, consolidated coal dust treated with SZS1-5 had a stronger resistance to wind and rain. The screening, mineralization and dust suppression potential analysis of these two urease-producing bacteria can provide reference for the application of MICP technology in coal dust suppression.

Facile fabrication of rape straw biomass fiber/β-CD/Fe3O4 as adsorbent for effective removal of ibuprofen

Wastewater containing pharmaceuticals can be bioaccumulated, posing a potential risk to drinking water, human health, and ecosystems. In order to make the adsorption process more suitable for actual application, rape straw biomass fiber (treated by an acidified sodium chlorite solution, 5%) and Fe3O4 embedded β-CD to prepare a novel adsorbent (RSBCDF), which was used for the removal of ibuprofen (IBP) from aqueous solution. The RSBCDF was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) measurements, scanning electron microscopy (SEM), and zeta potential measurements. The synthesized adsorbent was studied with regard to IBP removal percent under different adsorption conditions such as varying initial pH levels (4–10), initial ibuprofen concentrations (20−160 mg/L), contact time (5−150 min), and the dosage of adsorbent (10−100 mg) via batch adsorption experiments. The adsorption kinetics, thermodynamics, and isotherms were also investigated. The IBP adsorption behaviour followed a pseudo-second-order kinetic model and the Freundlich isotherm model. The maximum adsorption capacity obtained for ibuprofen was 48.29 mg/g. The values of Gibbs free energy change were negative (-2.58∼-3.56KJ/mol), suggesting that the process of ibuprofen adsorption onto adsorbent was spontaneous. The positive value of standard enthalpy change (12.09 kJ/mol) indicated that the adsorption process was endothermic. The obtained results prove that RSBCDF is a proficient and economically suitable material for removing IBP from water environments.

Ammonia Bioremediation from Aquaculture Wastewater Effluents Using Arthrospira platensis NIOF17/003: Impact of Biodiesel Residue and Potential of Ammonia-Loaded Biomass as Rotifer Feed.

The present work evaluated the capability of Arthrospira platensis complete biomass (ACDW) and the lipid-free biomass (LFB) to remove ammonium ions (NH4+) from aquaculture wastewater discharge. Under controlled conditions in flasks filled with 100 mL of distilled water (synthetic aqueous solution), a batch process ion-exchange was conducted by changing the main parameters including contact times (15, 30, 45, 60, 120, and 180 min), initial ammonium ion concentrations (10, 20, 30, 40, 50, and 100 mg·L−1), and initial pH levels (2, 4, 6, 8, and 10) at various dosages of ACDW and LFB as adsorbents (0.02, 0.04, 0.06, 0.08, and 0.1 g). After lab optimization, ammonia removal from real aquaculture wastewater was also examined. The removal of ammonium using ACDW and LFB in the synthetic aqueous solution (64.24% and 89.68%, respectively) was higher than that of the real aquaculture effluents (25.70% and 37.80%, respectively). The data of IR and Raman spectroscopy confirmed the existence of various functional groups in the biomass of ACDW and LFB. The adsorption equilibrium isotherms were estimated using Freundlich, Langmuir, and Halsey models, providing an initial description of the ammonia elimination capacity of A. platensis. The experimental kinetic study was suitably fit by a pseudo-second-order equation. On the other hand, as a result of the treatment of real aquaculture wastewater (RAW) using LFB and ACDW, the bacterial counts of the LFB, ACDW, ACDW-RAW, and RAW groups were high (higher than 300 CFU), while the LFB-RAW group showed lower than 100 CFU. The current study is the first work reporting the potential of ammonia-loaded microalgae biomass as a feed source for the rotifer (Brachionus plicatilis). In general, our findings concluded that B. plicatilis was sensitive to A. platensis biomass loaded with ammonia concentrations. Overall, the results in this work showed that the biomass of A. platensis is a promising candidate for removing ammonia from aquaculture wastewater.

Removal of culturable bacteria from municipal wastewater using electrocoagulation

Many countries around the world are faced with a serious event that is the pollution of water and wastewater with biological pollutions. This is particularly true in developing nations because of the weak treatment and disposal practice of wastewater. The weak economic situation and low financial support in many low-income countries significantly reduce the development and the uses of innovative water and wastewater treatment methods. This has led to increases and enlarges the issue of water pollution biological pollutants. The goal of this research is to implement the electrocoagulation technique as a cheap and cost-effective technology to eliminate or reduce the per cent of biological pollutant from wastewater. The coagulants are produced in situ by passing a current between two electrodes. A sample of the wastewater was collected from the Kerbala sewage treatment plant, which is located in the southeast of Kerbala city, Iraq. Iron electrodes were used to produce the coagulants in this research study. Besides, the impact of several variables on the performance of the electrocoagulation unit was investigated including the spacing between electrodes and current density. The results revealed that the E. coli bacteria as biological indicator were destroyed after 40 minutes of treatment using iron electrodes with a spacing of 5mm and a current density of 2 mA/cm2. Besides, the outcome showed that an initial pH level of 6.0 is suitable for biological pollutants treatment using electrocoagulation.

Does cerebral near‐infrared spectroscopy (NIRS) help to predict futile cannulation in extracorporeal cardiopulmonary resuscitation (ECPR)?

Aim of the studyExtracorporeal cardiopulmonary resuscitation (ECPR) is an evolving technique to improve cardiopulmonary resuscitation (CPR) outcomes. Identifying a readily available tool helpful for predicting patient's outcome is warranted. The aim of the study was to evaluate the capability of cranial near-infrared spectroscopy (cNIRS) to identify non-survivors or patients with unfavorable neurologic outcome prior to cannulation for ECPR to avoid futile cannulations. MethodsRetrospective analysis (2015–2021) of 97 patients requiring ECPR due to cardiac arrest with prior cNIRS measurement, which was performed immediately after ECPR team arrived on scene. Lowest possible regional cerebral oxygen saturation (rSO2) is 15%. ResultsMortality was 72.1% (70/97). Survivors showed in 88.9% (24/27) good neurological outcome (Cerebral Performance Category (CPC) 1 + 2). rSO2 = 15% (11/97) prior to cannulation was only found in non-survivors. Among survivors, initial rSO2 was not associated with neurological outcome. Non-shockable initial rhythm was associated with higher mortality (44/50). In survivors, time to ECPR was shorter (p = 0.006), and initial lactate was significantly lower, whereas initial pH and hemoglobin levels were higher (p = 0.001). Survivors and those with favorable neurological outcome showed lower maximal NSE levels in the first 72 hours (p < 0.001; p = 0.041). ConclusionIn our patient cohort, rSO2 = 15% immediately prior to cannulation for ECPR did not result in any survivors, thus might be a marker for futile cannulation in ECPR. Higher rSO2 values were not associated with favorable neurologic outcome. Lower initial lactate and lower maximal NSE within the first 72 h after arrest were associated with favorable outcome.

Removal of Hexavalent Chromium using Iron Nanoparticles Prepared using Date Seed Extract

Removal of hexavalent chromium from contaminated water systems is critical due to their high toxicity to aquatic and human health. Iron based nanoparticles (FeNPs) have emerged as promising materials for chromium removal. However, greener alternatives to the chemical synthesis routes of FeNPs are highly desirable while retaining their remediation ability. In this study we evaluate the removal efficiency of chromium using iron nanoparticles synthesized using aqueous extracts of date tree seeds (ds-FeNPs). Characterization of ds-FeNPs reveal the presence of 20-100 nm spherical nanoparticles containing Fe, C, O and S elements. Batch experiments demonstrated that the removal efficiency increased with increase in nanoparticles dose for a fixed chromium concentration (from 18 to 98% at nanoparticles dose of 166 to 1000 mg/L), whereas an opposite trend was observed for varying chromium concentrations at fixed nanoparticles dose. Removal efficiency was also probed at different initial pH levels and results indicate complete removal of chromium in acidic pH (100% at pH 3) whereas basic pH hindered chromium removal.

Blunt Cardiac Injuries That Require Operative Management: A Single-Center 7-Year Experience

Purpose Blunt cardiac injuries (BCI) have a wide clinical spectrum, ranging from asymptomatic myocardial contusion to cardiac rupture and death. BCIs rarely require surgical intervention, but can be rapidly fatal, requiring prompt evaluation and surgical treatment in some cases. The aim of this study was to identify potential factors associated with in-hospital mortality after surgery in patients with BCI. Methods The medical records of 15 patients who had undergone emergency cardiac surgery for BCI between January 2014 and August 2020 were retrospectively reviewed. We included trauma patients older than 18 years admitted to Regional Trauma Center, Gachon University Gil Medical Center during the study period. Clinical and laboratory variables were compared between survivors and non-survivors. Results Non-survivors showed a significantly higher Injury Severity Score (p=0.001) and Abbreviated Injury Scale in the chest region (p=0.001) than survivors. American Association for the Surgery of Trauma-Organ Injury Scale Grade V injuries were significantly more common in non-survivors than in survivors (p=0.031). Non-survivors had significantly more preoperative packed red blood cell (PRBC) transfusions (p=0.019) and were significantly more likely to experience preoperative cardiac arrest (p=0.001) than survivors. Initial pH (p=0.010), lactate (p=0.026), and base excess (BE; p=0.026) levels showed significant differences between the two groups. Conclusions Initial pH, lactate, BE, ventricular injury, the amount of preoperative PRBC transfusions, and preoperative cardiac arrest were potential predictors of in-hospital mortality.

Unconfined compressive strength of bio-cemented sand: state-of-the-art review and MEP-MC-based model development

As a clean and sustainable method, the microbially induced calcite precipitation (MICP) approach has been widely used for reinforcing weak soils. This study presents a state-of-the-art review on the unconfined compressive strength (UCS) of bio-cemented sand treated by MICP, followed by the high-performance prediction using a machine learning algorithm combined with the Monte-Carlo (MC) method. First, various influencing parameters affecting the UCS of bio-cemented sand are identified, such as initial relative density, angularity of particle shape, bacterial concentration, precipitated calcium carbonate content, temperature and degree of saturation. Besides, the particle size distribution, urea and calcium concentration, and initial pH level also influence the UCS of the bio-cemented sand, but the effects remain contradictory or unclear. Following the state-of-the-art review, a large database covering 351 bio-cemented sand samples is developed, with the UCS as the output and seven influencing parameters (median grain size, coefficient of uniformity, initial void ratio, optical density of bacterial suspension, urea concentration, calcium concentration and precipitated calcium carbonate content) as inputs for the correlation. The multi expression programming (MEP) method combined with the MC method is proposed to develop the prediction models. All data groups randomly generated from the database are with 80% of the samples as the training sets and 20% as the testing sets. Finally, the optimal prediction model is selected with the lowest mean absolute error, further based on the analyses of monotonicity, sensitivity and robustness regarding more general applications.

Eco-friendly approach for efficient catalytic degradation of organic dyes through peroxymonosulfate activated with pistachio shell-derived biochar and activated carbon

ABSTRACT This study introduces a simple method for the preparation of biochar (BCP) and activated carbon using pistachio (ACP) external hull as residual solid waste. Low-cost raw materials, biodegradable, recyclable and organic solid wastes are advantages of this method. Furthermore, complete degradation of methyl orange (MO) and methylene blue (MB) to H2O and CO2 as eco-friendly compounds in mild reaction condition occurs at a short time. Also, the effects of crucial parameters (temperature, time, catalyst dosage, initial dye and oxidant concentration, initial reaction pH level and radical scavengers), capability, adaptability, performance and reusability of ACP were also evaluated. The results displayed that dyes could be decomposed effectively by the PMS/ACP-800 system. Furthermore, the sulphate radical () was a major active role in the degradation process, while hydroxyl radical ( • OH) played a minor role. Overall, ACP had yielded high degradation of MB and MO dyes; therefore, ACP-800 could be effectively and reliably applied in the treatment of industry effluents containing MB and MO dyes.

Liming agricultural soils in Western Kenya: Can long-term economic and environmental benefits pay off short term investments?

ContextSoil acidification affects crop yields which can diminish farmers' incomes. Whilst soil pH can easily be increased by application of lime, in practice application must be economically viable with yield benefits offering an acceptable return on investments. Liming is a long-term investment with benefits becoming apparent over multiple years. Long-term economic strategies can be problematic for farmers who lack investment capital and who may have short-term decision time frames, such as most smallholder farmers in sub-Saharan Africa. In addition, application of lime causes substantial greenhouse gas (GHG) emissions (especially CO2). It is currently unclear how liming affects GHG emissions per tonne of maize, in cases where liming increases crop yields. ObjectiveIn this study, we assessed if liming acid soils is economically and environmentally viable at different levels of intensification for maize cultivation in Western Kenya. MethodsFirst, a meta-analysis using a regression analysis was conducted to quantify effects of lime application on soil pH and maize yields based on 26 field experiments. Related effects on farm profit and and returns on investment were estimated for a period of five years for soils with varying levels of initial soil pH and fertiliser application. Finally, synergies and trade-offs were assessed between maize yields, economic benefits and GHG emissions. Results and conclusionsLiming consistently increased maize yields on soils with an initial soil pH between 4.0 and 5.7 in Western Kenya, with or without fertiliser use. For a soil pH of 5, applying 2 t ha−1 lime resulted in a significant increase in maize yields of 57% (from 2.3 to 3.6 t ha −1) in the first year after application. Despite these positive effects on yield, associated profits – when including costs of labour - were only positive when liming was combined with fertiliser (N,P) application. While liming causes substantial GHG emissions per tonne lime applied, these were offset when expressing GHG emissions per tonne of grain maize, due to the observed yield increases. The pay-back period for lime investments was at least two years. SignificanceOur analysis shows that liming has potential co-benefits for food security and the environment in tropical acid soils, but we expect uptake by farmers to be unlikely without external incentives, at least in Western Kenya.

Functionalized Stink Bean Pod (Parkia speciosa) Powder for Adsorption of Reactive Dye

The potential of agricultural waste materials for removing synthetic dye, Remazol Brilliant Blue R (RBBR) and Remazol Brilliant Violet 5R (RBV5) from aqueous solution were investigated. Water pollution is one of the major environmental issues; dyes have contributed enormous damage to water bodies and greatly impact human health due to high toxicity and carcinogenic by nature. Agricultural wastes are sustainable adsorbents and generally low cost, which has the potential to replace traditional activated carbon. Therefore, this study investigated the removal of RBBR and RBV5 dye from the aqueous solution by adding adsorbent through adsorption. Stink bean pod (Parkia speciosa) was selected as the main adsorbent of this study. The experiment was carried out to study the effect of different initial dye concentration, adsorbent dosage, contact time, and pH level of dye solution. The results have shown that different parameters can affect the removal rate and adsorption capacity of adsorbents in different ways. The adsorption of dye from aqueous solution onto adsorbent was assessed using Fourier Transform Infrared Spectroscopy (FTIR) to determine the functional groups of adsorbent before and after the adsorption process. The FTIR results show that the functional group would affect the removal rate and adsorption capacity of adsorbents. The present study indicates that 83.35% of RBBR with the adsorption capacity of 1.23 mg/g was removed by a 3 g stink bean pod. In comparison, 80.07% of RBV5 with the adsorption capacity of 1.22 mg/g was removed by a 3 g stink bean pod. Design-Expert software was used to generate the equation, which represents the behavior for the adsorption of RBBR and RBV5 dye. The results proved that stink bean pod was promising material as an alternative adsorbent for the removal of dye from aqueous solution.

Aerosol dynamics simulations of the anatomical variability of e-cigarette particle and vapor deposition in a stochastic lung

Electronic cigarette (EC) aerosols are typically composed of a mixture of nicotine, glycerine (VG), propylene glycol (PG), water, acidic stabilizers and a variety of flavors. Inhalation of e-cigarette aerosols is characterized by a continuous modification of particle diameters, concentrations, composition and phase changes, and smoker-specific inhalation conditions, i.e. puffing, mouth-hold and bolus inhalation. The dynamic changes of inhaled e-cigarette droplets in the lungs due to coagulation, conductive heat and diffusive heat/convective vapor transport and particle phase chemistry are described by the Aerosol Dynamics in Containment (ADiC) model. For the simulation of the variability of inhaled particle and vapor deposition, the ADiC model is coupled with the IDEAL Monte Carlo code, which is based on a stochastic, asymmetric airway model of the human lung. We refer to the coupled model as “IDEAL/ADIC_v1.0”. In this study, two different e-cigarettes were compared, one without any acid (“no acid”) and the other one with an acidic regulator (benzoic acid) to establish an initial pH level of about 7 (“lower pH”). Corresponding deposition patterns among human airways comprise total and compound-specific number and mass deposition fractions, distinguishing between inhalation and exhalation phases and condensed and vapor phases. Note that the inhaled EC aerosol is significantly modified in the oral cavity prior to inhalation into the lungs. Computed deposition fractions demonstrate that total particle mass is preferentially deposited in the alveolar region of the lung during inhalation. While nicotine deposits prevalently in the condensed phase for the “lower pH” case, vapor phase deposition is dominating the “no acid” case. The significant statistical fluctuations of the particle and vapor deposition patterns illustrate the inherent anatomical variability of the human lung structure.

Sewage Sludge Valorization via Hydrothermal Carbonization: Optimizing Dewaterability and Phosphorus Release

As the use of sewage sludge as a fertilizer in agriculture is increasingly restricted in the European Union, other ways to utilize this waste stream need to be developed. Sewage sludge is an ideal input material for the process of hydrothermal carbonization, as it can convert wet biomass into a solid energy carrier with increased mechanical dewaterability. Digested sewage sludge was hydrothermally carbonized at 160–200 °C for 30–60 min with initial pH levels of 1.93–8.08 to determine optimal reaction conditions for enhanced dewaterability and phosphorus release into the liquid phase. Design of experiments was used to develop response surface models, which can be applied to optimize the process conditions. For optimal dewaterability and phosphorus release, low initial pH values (pH 1.93) and mild temperatures around 170 °C are favorable. Because holding time had no statistically relevant effect, a dependency of reaction time was investigated. Though it did not yield substantially different results, it could be included in investigations of short reaction times prospectively. Low reaction temperatures and short holding times are desirable considering economic reasons for scale-up, while the high acid consumption necessary to achieve these results is unfavorable.

Dark fermentation of starch factory wastewater with acid- and base-treated mixed microorganisms for biohydrogen production

Biohydrogen (Bio-H2) can be produced from starch factory wastewater and mixed microorganisms using dark fermentation. Acidic and basic chemicals were used to treat the microorganisms to select the hydrogen (H2)-producing culture. The experiment used a 120 mL bioreactor at 35 °C and the operation commenced with the initial pH level of wastewater in the pH range 4–7 in batch mode. The bacteria:chemical oxygen demand (COD) ratio was 0.2. The initial pH level of the wastewater in the fermentation process affected the H2 yield and the specific hydrogen production rate (SHPR). For acid-treated bacteria, the maximum H2 yield and SHPR were produced at an initial pH of 6.5. The maximum H2 yield and SHPR were 138 mL/g COD degraded and 7.42 mL/g cells‧h, respectively. For the base-treated bacteria, the maximum H2 yield and SHPR were produced at initial pH of 6.5 and pH 7, respectively. The maximum H2 yield and SHPR were 182 mL/g COD degraded and 25.60 mL/g cells‧h, respectively. The COD degradation efficiency levels were 16 and 20% for acid- and base-treated bacteria, respectively. The digested wastewater remained acidic at pH 4.79–4.83. Throughout the study, no methane gas was observed in the gas mixture produced.

A Natural Montmorillonite-Based Magsorbent as an Effective Scavenger for Cadmium Contamination

In this study, a magnetic montmorillonite composite (MMC) was prepared by a coprecipitation method, evaluated as sorbent for Cd(II) ions and characterized by IR spectroscopy, SEM, EDX, VSM, and zeta potential measurement. The adsorption potential of MMC was tested in both batch and continuous modes at different initial pH levels, sorbent dosages, contact times, ionic strengths, flow rates, and bed depths. The adsorption performance of MMC was found maximum at an original solution pH of 5.9 with 0.18 g sorbent for Cd(II). Fast adsorption equilibrium was established within 10 min. Kinetic and isotherm studies showed that the adsorption data followed the pseudo-second-order kinetic model and Langmuir isotherm. The maximum monolayer adsorption capacity of MMC was 0.325 mmol g−1. Cd(II) adsorption was mainly controlled by ion exchange, electrostatic interaction, and surface complexation mechanisms. Desorption and reusability studies revealed that MMC can be a promising alternative for the effective adsorption of Cd(II) in aqueous solutions of environmental remediation.

Effect of HNO3 and H2SO4 on the Paddy Ecosystem: A Mesocosm Study with Exposure at PNEC and HC50 Levels.

Paddy mesocosms comprising of rice (Oryza sativa), snail (Pomacea canaliculata), and worm (Tubifex tubifex) were used to assess the damage caused by two acids (HNO3 and H2SO4) at predicted no-effect concentration (PNEC) and hazardous concentration for 50% of species (HC50) levels. In the fourth week, the fresh weight and shoot height of O. sativa at H2SO4-HC50 were reduced by 83.2% and 30.3%, respectively. Wilted leaves (%) at HC50 were approximately twice that at PNEC. No P. canaliculata and T. tubifex were recovered at HC50. At H2SO4-PNEC, the length and weight of P. canaliculata were reduced by 7.4% and 25.9%, respectively, whereas fewer adult (46.5%) and juvenile (84%) T. tubifex were recovered. In the 20th week, rice growth and productivity were correlated with initial pH (pHi) and nitrogen levels. Poor correlation with chlorophyll at the active tillering stage suggests the disturbance of nutrient uptake by roots. Partial least squares path modeling (PLS-PM) results further supported that the pHi directly affects grain yield and quality, as well as plant growth. The indirect effect via intervening fourth-week-variables was also substantial. Therefore, it is important to measure initial pH upon acid spill to estimate the risk to the paddy ecosystem. Information on the change in soil properties associated with acidity will also aid in predicting the yield and quality of grain to be harvested.