Conductive Material to Enhance Organic Waste Biodegradation

Anaerobic digestion (AD) is a biological method widely used to treat wastes and wastewater containing high levels of organic matter in the absence of oxygen to convert chemical energy in organic carbon to biogas. With AD, the waste volume can be reduced drastically with green energy generation simultaneously. In practical applications, complex structure or toxicity of substrates often impair AD performance associated with low degradation rate and unstable biogas production. Electron transfer among different guilds of microorganisms is the rate-limiting step of AD process, and it is also the basic reason behind the deteriorated AD performance.

This technology relates to the dosing of conductive materials which can facilitate interspecies electron transfer and improve the overall metabolic activity in anaerobic digestion. In addition, it is a green and cost-effective technology as those selected materials (e.g. biochar, activated carbon, and iron scrap) can be readily obtained from nature or produced from wastes and recovered for repeated use.

The technology provider is looking for waste and wastewater biological treatment providers to license and commercialize this technology.

This technology is based on promoting rate-limiting step (i.e. interspecies electron transfer) of anaerobic digestion. By dosing conductive materials into the AD reactors, the interspecies electron transfer, and the overall metabolic activity can be increased, resulting in improved organics removal, biogas generation, and system stability. A brief specification of this technology is as follows:

• Conductive materials originated from natural or recovered from wastes are chosen as the dosing materials.
• The technology is especially helpful to solve operational problems triggered by refractory or toxic compounds.
• Only conductive materials dosing into the existing anaerobic reactors is necessary for this technology, and no extra facilities or power is needed.
• The conductive materials-assisted digestors could significantly reduce the input-output ratio of AD application. This is because the chosen materials are cheap, and the dosing amount is relatively low, e.g. iron-based materials (1–50 mmol-Fe/L), carbon-based materials (0.1–0.5 g-/L carbon). In addition, the methane yield can be improved simultaneously.

Onsite dosing of conductive materials is effective to maintain the performance of an AD system suffering from:

1. Slow organics removal rate
2. Low recalcitrant compounds conversion efficiency
3. System instability due to toxic substances in influent.

This technology is applicable in the following areas:

1. Food waste management
2. Industrial waste and wastewater management
3. Agricultural waste management

Anaerobic digestion (AD) has been increasingly adopted worldwide for waste management and energy production. However, various types of feedstocks can pose a potential risk to the performance of an AD system and impedes its application. Onsite dosing of conductive materials represents an economically viable and easy-operating solution for improving AD performance. For example, the organic degradation rate and methane yield of wastewater increased by 1.3 times and 30% after dosing activated carbon into digestors treating waste activated sludge. Therefore, this technology will significantly improve waste disposal capability, energy recovery efficiency as well as the economic benefits of the AD system.

Biogas generation and overall organic waste removal efficiency can be significantly improved. The conductive system can aid microbes to resist toxicity and degrade refractory compounds. This technology provides a sustainable approach to further enhance the existing biosystem robustness and stability.