Nitrogen management in nitrification-hydroponic systems by utilizing their pH characteristics

Rooyen, Ignatius Leopoldus van; Nicol, Willie

doi:10.1016/j.eti.2022.102360

Cited by 8 publications

(6 citation statements)

References 35 publications

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“…In contrast, applying nitrified FWAD with facilitated nitrification using nitrification reactors caused an increase in pH from 5.3 to 6.6 associated with increases in NO 3 − content and plant NO 3 − uptake. Van Rooyen and Nicol [45] also demonstrated that in the presence of ammonia oxidizing bacteria, the conversion of NH 4 + to NO 3 − induces an acidic effect due to the oxidation of NH 4 + , and it was reported that NH 4 + oxidation was being carried out by bacteria ten times faster than the NH 4 + absorption rate by plants alone. Using this relationship, it has been suggested to add NH 4 + in the form of FWAD when the nutrient solution becomes basic, or to add KOH or NO 3 − using the nitrified FWAD when the nutrient solution has an acidic pH [14,45].…”

Section: Ph Fluctuationmentioning

confidence: 99%

Potential Applications of Food-Waste-Based Anaerobic Digestate for Sustainable Crop Production Practice

2023

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The global food system is and will be facing many challenges in the coming decades, which will necessitate innovative solutions to address the issues of a diminishing fertilizer supply, an increasing food demand from growing populations, and frequent extreme climates due to greenhouse gas emissions. An advancement proposed is the synthesizing of fertilizer from food waste, here referred to as food waste anaerobic digestate (FWAD). This occurs through the process of anaerobic digestion, where organic matter such as food waste is contained in an anaerobic environment and allowed to be broken down by microorganisms. One of the resulting products is anaerobic digestate, which possesses the necessary nutrients for effective fertilization for crop production. In addition to reducing greenhouse gases and waste in landfills, the replacement of synthetic fertilizers with ones made from food waste would help to alleviate the impacts of the current fertilizer shortage being experienced worldwide, which will be exacerbated by a reducing supply of materials needed for synthetic fertilizer production. In this paper, we discuss the nutrient characteristics of FWAD, and recent studies utilizing FWAD in horticulture and crop production, to advance our understanding of the effectiveness and challenges of using FWAD as a fertilizer. By employing appropriate application methods, such as nitrification, dilution, and amendment, FWAD demonstrates considerable potential as an effective fertilizer for a wide range of leafy greens and some fruiting crops.

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Section: Ph Fluctuationmentioning

confidence: 99%

Potential Applications of Food-Waste-Based Anaerobic Digestate for Sustainable Crop Production Practice

2023

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“…The high rates of extracellular enzymes produced by T. versicolor have made this strain an attractive candidate to treat HTL-AP and generate ammonium/ammonia. In order for HTL-AP to be used as an alternative hydroponic nutrient solution, it is necessary for the organic forms of nitrogen to be converted to ammonia, which can then be converted to nitrate; this has been previously accomplished by nitrifying bacteria [20]. The most studied nitrifying bacteria consist of Nitrosomonas and Nitrobacter since the other reported genera of nitrifying bacteria have not been well characterized and many of them have been unable to carry out nitrification successfully [18].…”

Section: Introductionmentioning

confidence: 99%

Wastewater Nutrient Recovery via Fungal and Nitrifying Bacteria Treatment

Lopez,

Leme,

Warzecha

et al. 2024

Agriculture

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In efforts to reduce the consumption of fossil fuels and promote recycling biowaste, there is an interest in the production of post-hydrothermal liquefaction wastewater (HTL-AP) from the hydrothermal liquefaction (HTL) process that converts wet biomass into biocrude oil. This study explores ways of transforming potentially toxic HTL-AP into a fertilizer source for hydroponic cropping systems. This study specifically investigates the integration of the white-rot fungus Trametes versicolor with nitrifying bacteria (Nitrosomonas and Nitrobacter) to convert the organic nitrogen compounds into inorganic nitrogen while also producing the enzyme laccase, which has been shown to remove toxic compounds. This study aims to increase the concentration of nitrate-N to valorize wastewater as a suitable fertilizer by measuring several parameters, including laccase activity, pH, nitrate-N, and ammonia/ammonium-N concentrations, and analyzes interactions to optimize the conversion process. The data support the claim that the simultaneous inoculation of T. versicolor and nitrifying bacteria significantly increases nitrate-N concentrations in HTL-AP, as it increased by 17 times, or an increase of 32.69 mg/L. In addition, HTL-AP treated with T. versicolor and nitrifying bacteria reduced the treatment time by 120 h, highlighting a reduction in personnel time and energy consumption. Therefore, this research accentuates sustainability through fungal and bacterial treatments to develop eco-friendly hydroponic fertilizers. Future research should explore the potential of utilizing the combination of T. versicolor and nitrifying bacteria for the treatment of other industrial wastewaters.

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“…Organic carbon being present in hydroponic media typically results in the growth of heterotrophic bacteria on plant roots, which has the potential to severely inhibit growth [13]; this is also referred to as Pythium root rot [21]. In addition, plants prefer N in the form of nitrate as opposed to ammonia [22,23] and, accordingly, crude digestate requires further processing before being used as an effective hydroponic medium. The first processing step entails the removal of organic carbon and is referred to as the polishing step.…”

Section: Introductionmentioning

confidence: 99%

Aerobic Polishing of Liquid Digestate for Preparation of Hydroponic Fertiliser

Mathe,

Ramsumer,

Brink

et al. 2024

Sustainability

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Nutrient pollution—mainly nitrogen and phosphorus—caused by organic waste continues to impact the environment. The implementation of a circular economy is integral to alleviating these effects. Liquid digestate, which is a byproduct of anaerobic digestion (a waste-valorising process), is a nutrient-dense organic fertiliser with vast applications in agriculture. Using an aerobic polishing unit, this study developed a viable method for the preparation of a hydroponic fertiliser by investigating the effect of pH on the nutrient recycling capabilities of said system. The heterotrophic bacteria present in the biofilm, identified by 16S gene sequencing, are responsible for 90% of organic carbon (as TOC) removal with minimal ammonium loss. This is ideal for promoting optimal nitrification in hydroponic systems in the absence of organic carbon to ensure plant growth is not affected. Although pH 8 was found to be ideal for batch operation, this pH condition resulted in decreased microbial longevity and, therefore, increased ammonification due to microbial decay. Therefore, continuous operation at pH 7 proved to be a better option owing to the ammonium-rich effluent (>220 mg/L) which was produced, which is on par with the nitrogen concentration of a Hoagland solution. The continuous carbon polishing of liquid digestate provides an efficient way of utilising organic fertilisers in hydroponic systems.

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Nitrogen management in nitrification-hydroponic systems by utilizing their pH characteristics

Cited by 8 publications

References 35 publications

Potential Applications of Food-Waste-Based Anaerobic Digestate for Sustainable Crop Production Practice

Potential Applications of Food-Waste-Based Anaerobic Digestate for Sustainable Crop Production Practice

Wastewater Nutrient Recovery via Fungal and Nitrifying Bacteria Treatment

Aerobic Polishing of Liquid Digestate for Preparation of Hydroponic Fertiliser

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