Nitrate removal under low carbon to nitrogen ratio by modified corn straw bioreactor: Optimization and possible mechanism.

ABSTRACTThe removal of nitrate (NO3--N) from water bodies under the conditions of poor nutrition and low carbon to nitrogen (C/N) ratio is a widespread problem. In this study, modified corn stalk (CS) was used to immobilize Burkholderia sp. CF6 with cellulose-degrading and denitrifying abilities. The optimal operating parameters of the bioreactor were explored. The results showed that under the hydraulic retention time (HRT) of 3 h and the C/N ratio of 2.0, the maximum nitrate removal efficiency was 96.75%. In addition, the organic substances in the bioreactor under different C/N ratios and HRT were analyzed by three-dimensional fluorescence excitation-emission mass spectrometry (3D-EEM), and it was found that the microorganisms have high metabolic activity. Scanning electron microscope (SEM) showed that the new material has excellent immobilization effects. Fourier transform infrared spectrometer (FTIR) showed that it has potential as a solid carbon source. Through high-throughput sequencing analysis, Burkholderia sp. CF6 was observed as the main bacteria present in the bioreactor. These research results showed that the use of waste corn stalks waste provides a theoretical basis for the advanced treatment of low C/N ratio wastewater.

Newly isolated lysozyme-producing strain Proteus mirabilis sp. SJ25 reduced the waste activated sludge: Performance and mechanism.

To promote aerobic digestion of sludge, a lysozyme-producing strain was screened and identified as Proteus mirabilis sp. SJ25. The results of response surface methodology (RSM) showed that at the temperature of 30.8 °C, pH of 6.69, and the inoculum amount of 2.81%, the sludge reduced by 26.58%. Compared with the control group, the removal efficiency of suspended solids (SS) from sludge in the experimental group increased by 14.60%, the release of soluble chemical oxygen demand (SCOD) increased by 2.21 times, and the release of intracellular substances increased significantly. Actinobacteriota, Chloroflexi, Proteobacteria, Bacteroidota, and Firmicutes were the main phyla involved in the sludge reduction process. Strain SJ25 enhanced the degradation rate of sludge by releasing lysozyme lysis to lyse bacteria, enhancing the metabolism and membrane transport of carbohydrates and amino acids. This study provides a new perspective in the field of efficient degradation of waste sludge.

Biochar fungal pellet based biological immobilization reactor efficiently removed nitrate and cadmium.

To efficiently and simultaneously remove nitrate (NO3--N) and Cd(II) from aqueous solution, a novel type of biochar fungal pellet (BFP) immobilized denitrification bacteria (Cupriavidus sp. H29) composite was used in a bioreactor. The removal performance of the bioreactor R1 for the initial concentration of 27.7 mg L-1 nitrate and 10.0 mg L-1 Cd(II) reached 98.1 and 93.9% respectively, and the inoculation of strain H29 in bioreactor R1 significantly enhanced the removal efficiency of contaminants. The 3D-EEM spectra analysis showed that the activity of microorganisms in the bioreactor was higher at a lower concentration of Cd(II). FTIR indicated the effect of functional groups in BFP in bioadsorption of Cd(II). In addition, high-throughput analysis of species composition of the microbial community in the bioreactors at different levels demonstrated that strain H29 played a significant part in the bioreactor. This research provided a perspective for simultaneous restoration of nitrate and heavy metals in wastewater, and also enriched the application of fungal pellet (FP) in reactors.

Phenol and 17ß-estradiol removal by Zoogloea sp. MFQ7 and in-situ generated biogenic manganese oxides: Performance, kinetics and mechanism.

The pollution of multifarious pollutants such as heavy metal, organic compounds, and nitrate are a hot research topic at present. In this study, the functions of Zoogloea sp. MFQ7 and its biological precipitation formed during bacterial manganese oxidation on the removal of phenol and 17ß-estradiol (E2) were investigated. Strain MFQ7, a manganese-oxidizing bacteria, can remove 98.34% of phenol under pH of 7.1, a temperature of 30 â„ƒ and Mn2+ concentration of 24.34 mg L-1, additionally, the optimum E2 removal by strain MFQ7 was 100.00% at pH of 7.1, temperature of 28 â„ƒ and Mn2+ concentration of 28.45 mg L-1 by using response surface methodology (RSM) based on Box-Behnken design (BBD) model. The maximum adsorption capacity of bio-precipitation for phenol and E2 was 201.15 mg g-1 and 65.90 mg g-1, respectively. Furthermore, adsorption kinetics and isotherms analysis, XPS, FTIR spectra, Mn(III) trapping experiments elucidated chemical adsorption and Mn(III) oxidation contribute to the removal of phenol and E2 by biogenic manganese oxides. These findings indicated that the adsorption and oxidation of manganese are expected to be one of the effective means to remove these typical organic pollutants containing phenol and E2.

Changes in Domestic Energy and Water Usage during the UK COVID-19 Lockdown Using High-Resolution Temporal Data.

In response to the COVID-19 outbreak, the UK Government provided public health advice to stay at home from 16 March 2020, followed by instruction to stay at home (full lockdown) from 24 March 2020. We use data with high temporal resolution from utility sensors installed in 280 homes across social housing in Cornwall, UK, to test for changes in domestic electricity, gas and water usage in response to government guidance. Gas usage increased by 20% following advice to stay at home, the week before full lockdown, although no difference was seen during full lockdown itself. During full lockdown, morning electricity usage shifted to later in the day, decreasing at 6 a.m. and increasing at midday. These changes in energy were echoed in water usage, with a 17% increase and a one-hour delay in peak morning usage. Changes were consistent with people getting up later, spending more time at home and washing more during full lockdown. Evidence for these changes was also observed in later lockdowns, but not between lockdowns. Our findings suggest more compliance with an enforced stay-at-home message than with advice. We discuss implications for socioeconomically disadvantaged households given the indication of inability to achieve increased energy needs during the pandemic.

[Phosphorus Removal Performance and Mechanism of Modified Zeolite Using Alum Sludge Acidified Extraction Liquid].

To improve the capacity for phosphorus removal and to reduce the cost of treatment, alum sludge from a water supply plant was obtained to prepare modified zeolite coated with layered double hydroxide (LDHs), which was synthesized using an acidified extraction liquid. The surface characteristics and chemical composition of raw zeolites, Al-Zn modified zeolites, and alum sludge modified zeolites were determined, and the isothermal adsorption and adsorption kinetics were analyzed. The performance and mechanism of phosphorus removal by the alum sludge modified zeolites were evaluated. The results showed that the optimum conditions for acidification extraction were 60 min treatment time, 150 r·min-1, and pH 1.0, which achieved 77 mg aluminum extraction rate per gram of alum sludge. Compared to raw zeolites, the maximum saturated adsorption capacity and the desorption performance of the zeolites were significantly increased by this modification. In addition, the theoretical maximum adsorption capacity of alum sludge modified zeolites was increased from 30.24 mg·kg-1 to 170.40 mg·kg-1. The modification changed the main mode of phosphate adsorption by zeolite from physical adsorption to chemical adsorption. Alum sludge modification could improve the efficiency of phosphate adsorption and the regeneration capacity of zeolite, which could reduce the risk of water eutrophication caused by high phosphate concentrations, and could achieve the purpose of waste control by waste.