Scientific, Cost-Effective Treatment for Anaerobic Digestion Waste

Scientific, Cost-Effective Treatment for Anaerobic Digestion Waste  Mirage News

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Oct 19, 2023 - 01:30
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Scientific, Cost-Effective Treatment for Anaerobic Digestion Waste

Sustainable Development Goals (SDGs) and the Utilization of Agricultural Waste

Higher Education Press

Introduction

The resource utilization of waste is an important means to implement the construction of ecological civilization. Agricultural waste contains rich renewable resources and has high potential value in fertilization and energy conversion. Anaerobic digestion technology is a promising technology for treating agricultural waste.

Anaerobic Digestion and its Advantages

Anaerobic digestion refers to the digestion technology in which organic matter is decomposed into CH4, CO2, H2O and H2S by facultative bacteria and anaerobic bacteria under anaerobic conditions, which can transform solid organic matter into soluble organic matter. Not only does it have the advantages of stable process and low operation cost, the biogas produced can also be used as a clean biomass energy, reducing air pollution.

Challenges of Anaerobic Digestate (LFD)

However, the digestate (LFD) discharged from the anaerobic device contains high chemical oxygen demand (COD) and phosphate concentration. If discharged directly without proper treatment, it may pose risks such as water eutrophication to the environment. Likewise, because of its high nutrient content, LFD can be used as organic fertilizer to reduce the application of mineral fertilizer and increase crop yield. However, its direct application as fertilizer is always limited by the growing season and the available arable land area, and the long-term application of LFD in farmland can lead to the loss of nutrients in the soil. The accumulated harmful metals in LFD pose a risk of migration to plants.

Treatment Technologies for LFD

Various treatment technologies for LFD have been reported, including:

  1. Chemical precipitation
  2. Flocculation-coagulation
  3. Air stripping
  4. Membrane separation
  5. Ion exchange
  6. Adsorption
  7. Evaporation
  8. Chemical oxidation or deep oxidation
  9. Microalgae cultivation

Chemical Precipitation and Fly Ash

Chemical precipitation is a widely used pretreatment method in wastewater treatment, aiming to remove phosphates, heavy metals, and organic pollutants. Coal fly ash, as a by-product of coal-fired power plants, has the potential to be used for the chemical precipitation of LFD. However, there are few reports on this aspect. The use of fly ash for chemical precipitation has the advantage of simultaneously removing several organic and inorganic pollutants. However, it also faces the problem of alkaline minerals and heavy metals in fly ash dissolving into LFD, which increases the cost and environmental risk of wastewater post-treatment.

New Method: Chemical Precipitation based on Fly Ash and CO2 Mineralization

To address these issues, a new method called chemical precipitation based on fly ash and CO2 mineralization was studied. This method aims to efficiently remove pollutants in LFD. The study determined the technical feasibility of this process, explored the potential mechanism of the reaction, studied the removal rate of pH, electrical conductivity (EC), total phosphorus (TP), COD, and heavy metals during the treatment process, and analyzed the physicochemical properties of fly ash and LFD before and after the experiment to determine the reaction mechanism.

Results and Conclusion

The study found that the pH and EC of LFD treated increased with the increase of fly ash concentration. The pH and EC of LFD after fly ash-based chemical precipitation decreased after CO2 bubbling treatment. The removal efficiency of COD increased with the increase of fly ash concentration, reaching a maximum of 93.8%. The removal of TP by fly ash-based chemical precipitation was even more significant, reaching 80% even at low concentrations of fly ash, and continuing to increase to 98% with the increase of fly ash concentration. Leaching experiments showed that the treated LFD had lower concentrations of toxic ions compared to untreated samples. The treated LFD can meet the requirements for irrigation water.

Significance and Publication

The theoretical significance of this study is that it explores a low-cost and efficient method for treating anaerobic digestate, providing a new idea for the resource utilization of agricultural waste. The practical significance is that this method can effectively remove pollutants in anaerobic digestate, reduce negative impacts on the environment, and provide high-purity calcium carbonate products, with potential economic and environmental benefits.

This study has been published on the Journal of Frontiers of Agricultural Science and Engineering in 2023, 10(3) DOI: 10.15302/J-FASE-2023480.

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SDGs, Targets, and Indicators

  1. SDG 6: Clean Water and Sanitation

    • Target 6.3: By 2030, improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials, halving the proportion of untreated wastewater, and substantially increasing recycling and safe reuse globally.
    • Indicator 6.3.2: Proportion of bodies of water with good ambient water quality.

  2. SDG 7: Affordable and Clean Energy

    • Target 7.2: By 2030, increase substantially the share of renewable energy in the global energy mix.
    • Indicator 7.2.1: Renewable energy share in the total final energy consumption.

  3. SDG 12: Responsible Consumption and Production

    • Target 12.4: By 2020, achieve the environmentally sound management of chemicals and all wastes throughout their life cycle, in accordance with agreed international frameworks, and significantly reduce their release to air, water, and soil in order to minimize their adverse impacts on human health and the environment.
    • Indicator 12.4.2: Hazardous waste generated per capita and proportion of hazardous waste treated, disaggregated by treatment type.

Analysis

  1. SDG 6: Clean Water and Sanitation

    The article discusses the treatment of agricultural waste, specifically the digestate (LFD) discharged from anaerobic digestion devices. If the LFD is discharged directly without proper treatment, it may pose risks such as water eutrophication to the environment. The article also mentions the removal of phosphates, heavy metals, and organic pollutants from wastewater. These issues are directly connected to SDG 6, which aims to ensure availability and sustainable management of water and sanitation for all.

  2. SDG 7: Affordable and Clean Energy

    The article highlights the use of biogas produced from anaerobic digestion as a clean biomass energy, reducing air pollution. This aligns with SDG 7, which focuses on ensuring access to affordable, reliable, sustainable, and modern energy for all.

  3. SDG 12: Responsible Consumption and Production

    The article discusses the resource utilization of waste and the need for efficient treatment technologies to manage agricultural waste. It also mentions the potential economic and environmental benefits of the new method studied. These aspects relate to SDG 12, which aims to ensure sustainable consumption and production patterns.

Table: SDGs, Targets, and Indicators

SDGs Targets Indicators
SDG 6: Clean Water and Sanitation Target 6.3: By 2030, improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials, halving the proportion of untreated wastewater, and substantially increasing recycling and safe reuse globally. Indicator 6.3.2: Proportion of bodies of water with good ambient water quality.
SDG 7: Affordable and Clean Energy Target 7.2: By 2030, increase substantially the share of renewable energy in the global energy mix. Indicator 7.2.1: Renewable energy share in the total final energy consumption.
SDG 12: Responsible Consumption and Production Target 12.4: By 2020, achieve the environmentally sound management of chemicals and all wastes throughout their life cycle, in accordance with agreed international frameworks, and significantly reduce their release to air, water, and soil in order to minimize their adverse impacts on human health and the environment. Indicator 12.4.2: Hazardous waste generated per capita and proportion of hazardous waste treated, disaggregated by treatment type.

Behold! This splendid article springs forth from the wellspring of knowledge, shaped by a wondrous proprietary AI technology that delved into a vast ocean of data, illuminating the path towards the Sustainable Development Goals. Remember that all rights are reserved by SDG Investors LLC, empowering us to champion progress together.

Source: miragenews.com

 

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