Combating hypoxia/anoxia is an increasingly common need for restoring natural waters suffering from eutrophication. Oxygen nanobubble modified natural particles were investigated for mitigating hypoxia/anoxia at the sediment-water interface (SWI) in a simulated column experiment. By adding oxygen nanobubble modified zeolites (ONMZ) and local soils (ONMS), the oxygen nanobubble concentrations (10-10 particles/mL) were several orders of magnitude higher in the water than the original water solution (10 particles/mL) within 24 h. In the column experiment, an oxygen-locking surface sediment layer was formed after capping with ONMZ and ONMS particles. The synergy of diffusion of oxygen nanobubbles and retention of oxygen in this layer contributes to both the increase of DO and reversal of hypoxic conditions. The overlying water had significantly higher dissolved oxygen (DO) values (4-7.5 mg/L) over the experimental period of 127 days in ONMZ and ONMS compared with the control systems (around 1 mg/L). Moreover, the oxidation-reduction potential (ORP) was reversed from -200 mV to 180-210 mV and maintained positive values for 89 days in ONMZ systems. In the control systems, ORP was consistently negative and decreased from -200 mV to -350 mV. The total phosphorus (TP) flux from sediment to water across the SWI was negative in the ONMZ and ONMS treated systems, but positive in the control system, indicating the sediment could be switched from TP source to sink. The oxygen-locking capping layer was crucial in preventing oxygen consumption caused by the reduced substances released from the anoxic sediment. The study outlines a potentially promising technology for mitigating sediment anoxia and controlling nutrient release from sediments, which could contribute significantly to addressing eutrophication and ecological restoration.

No abstract

No abstract

in CWs, and the removal can be described by an artificial neural network model.

Towards high-quality biodiesel production from microalgae using original and anaerobically-digested livestock wastewater, Chemosphere, https://doi.org/10.1016/j.chemosphere.2020.128578. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

21Development of technology to improve the mineralization of organic fertilizer and to enhance 22 crop production is essential to achieve the transition from traditional farming to eco-friendly 23 organic farming. Nanobubble oxygation (NB) was employed to compare with traditional pump 24 aerated oxygation (AW) and a control group through both soil incubation and soil column 25 experiments. Plant-available N and P contents in the NB treatment group were higher than 26 that in the AW and control groups. Enzymatic activities including β-1,4-N-acetyl-27 glucosaminidase, phosphatase, α-1,4-glucosidase, β-1,4-xylosidase, peroxidase, and phenol 28 oxidase were significantly higher in both oxygation groups compared with the control. The soil 29 microbial biomass, activity, and diversity were also significantly improved due to the oxygation 30 treatment. Additionally, the microbial metabolic functions were shifted in both oxygation 31 treatments compared with the control group. The final tomato yield increase from the NB 32 treatment group was 23%, and that from the AW treatment 17%, compared with the control. 33 4 36 52 the applied nutrients from the organic fertilizer can only be utilized by crops after 53 decomposition and mineralization of organic matter and release of plant-available nutrients, 54 such as nitrogen and phosphorous. It has been reported that only 35%, 39%, and 53% of the 55 plant-available nitrogen can be released from cow, pig and chicken manures on farmland over 56 6 months, respectively. 8 As a result, crop production in organic farming has been 57 demonstrated to be up to 25% lower than that in conventional agriculture using chemical Page 4 of 29 ACS Paragon Plus Environment Journal of Agricultural and Food Chemistry 5 58fertilizer. 9 This slow release of mineral nutrients from organic fertilizer has become the major 59 yield-limiting factor, 10 which indicates that further research could focus on the acceleration of 60 the mineralization of organic fertilizer in organic farming. 61The mineralization is driven by microbial biodegradation processes, where oxygen is 62 crucial in order to improve the bio-decomposition rate. The soil oxygen content in traditional 63 farmland originates mainly from air diffusion, which is always limited, especially in the deep 64 soil layer. Thus, an appropriate method to deliver sufficient oxygen into the soil is crucial to 65 improve microbial activity. The application of aerated water to the farmland through a drip 66 irrigation system has been used to deliver oxygen to the crop root zone. 11 Previous studies 67 demonstrated that these approaches could not only enhance crop yields, but could also 68 improve the nutrition quality of fruit. 12 To improve the soil oxygenation efficiency, the 69 aeration pump was upgraded from common air pumps, fine bubble diffusers and to venturi 70 injectors. 13 The main aim of the development of this technique was to deliver smaller-sized 71 air bubbles into irrigation water and to improve oxygen dissolution efficiency. Recen...

Interfacial nanobubbles can exist on various hydrophobic and hydrophilic material interfaces. There are diverse applications for oxygen nanobubbles, which are closely related to their content and long-term stability. However, it remains challenging to determine the amount of nanobubbles loaded in a porous material. In this study, a novel method was used to quantify the total amount of oxygen nanobubbles loaded onto irregular particulate materials. Different materials were evaluated and their oxygen-loading capacities were found to be as follows: activated carbon (AC) > zeolite > biochar > diatomite > coal ash > clay. Significant differences in oxygen-loading capacities were mainly ascribed to differences in the specific surface area and hydrophobic/hydrophilic properties of the materials. The total oxygen loading on AC achieved using the high pressure loading method was higher than that achieved by the temperature variation method. This new quantitative method provides the possibility for the manipulation of oxygen nanobubble materials in practical applications and it is anticipated to be an important supplement to the existing methods of characterizing interfacial oxygen nanobubbles. Our results demonstrate that materials containing oxygen nanobubbles can significantly increase the dissolved oxygen and oxidation reduction potential in anaerobic systems. With the addition of oxygen-loaded materials (such as AC), the survival time of zebrafish was prolonged up to 20 h in a deoxygenated water system, and the germination rate of Vallisneria spiralis was also increased from 27 to 73% in an anaerobic sediment.

Harmful algal blooms (HABs), eutrophication, and internal pollutant sources from sediment, represent serious problems for public health, water quality, and ecological restoration worldwide. Previous studies have indicated that Modified Local Soil (MLS) technology is an efficient and cost-effective method to flocculate the HABs from water and settle them onto sediment. Additionally, MLS capping treatment can reduce the resuspension of algae flocs from the sediment, and convert the algal cells, along with any excessive nutrients in-situ into fertilisers for the restoration of submerged macrophytes in shallow water systems. Furthermore, the capping treatment using oxygen nanobubble-MLS materials can also mitigate sediment anoxia, causing a reduction in the release of internal pollutants, such as nutrients and greenhouse gases. This paper reviews and quantifies the main features of MLS by investigating the effect of MLS treatment in five pilot-scale whole-pond field experiments carried out in Lake Tai, South China, and in Cetian Reservoir in Datong city, North China. Data obtained from field monitoring showed that the algae-dominated waters transform into a macrophyte-dominated state within four months of MLS treatment in shallow water systems. The sediment-water nutrient fluxes were substantially reduced, whilst water quality (TN, TP, and transparency) and biodiversity were significantly improved in the treatment ponds, compared to the control ponds within a duration ranging from one day to three years. The sediment anoxia remediation effect by oxygen nanobubble-MLS treatment may further contribute to deep water hypoxia remediation and eutrophication control. Combined with the integrated management of external loads control, MLS technology can provide an environmentally friendly geo-engineering method to accelerate ecological restoration and control eutrophication.