KR-20260062700-A - Method of Measuring Biochemical Methane Potential of Waste Activated Sludge

Abstract

The present invention relates to a method for measuring the biochemical methane potential of waste activated sludge, and more specifically, to a method for measuring the biochemical methane potential of waste activated sludge that provides quantitative criteria for the effective volume of the reactor and the daily biogas production in a biochemical methane potential (BMP) test using an inoculum that has undergone a pre-culture process.

Inventors

• 안종화
• 하승한

Assignees

• 강원대학교산학협력단

Dates

Publication Date

20260507

Application Date

20241029

Claims (10)

1. A method for measuring biochemical methane potential (BMP) including the following steps: (a) a step of pre-culturing the inoculum; and (b) a step of producing biogas by reacting a pre-cultured inoculum with waste activated sludge, Here, the pre-culture period is determined based on the working volume and daily biogas production of the reactor.
2. A method for measuring biochemical methane potential according to claim 1, characterized in that the value obtained by dividing the daily biogas production by the effective volume of the reactor is 0.03 to 0.04 (unit: mL biogas / mL working volume / day).
3. A method for measuring biochemical methane potential according to claim 1, characterized in that steps (a) and (b) are performed under the same conditions.
4. A method for measuring biochemical methane potential according to claim 1, characterized in that the inoculum is collected from anaerobic digester sludge, impurities are removed, and then refrigerated.
5. A method for measuring biochemical methane potential according to claim 1, wherein step (a) involves purging nitrogen gas from an inoculum and then sealing it to create an anaerobic state.
6. A method for measuring biochemical methane potential according to claim 1, characterized in that the waste activated sludge has a mass ratio of 1:0.5 to 2 with a pre-cultured inoculum based on VS (volatile solids).
7. A method for measuring biochemical methane potential according to claim 1, characterized in that the end point of step (a) is when the daily biogas production is 10 mL or less.
8. A method for measuring biochemical methane potential according to claim 1, characterized in that in step (a), the decomposition and fermentation of organic matter proceeds and the pH rises.
9. A method for measuring biochemical methane potential according to claim 1, characterized in that in step (a), a volatile fatty acid is converted into methane.
10. A method for measuring biochemical methane potential according to claim 1, characterized in that the SCOD (soluble chemical oxygen demand), TCOD (total chemical oxygen demand), VFA (volatile fatty acid), and VS (volatile solids) of the waste activated sludge are reduced.

Description

Method of Measuring Biochemical Methane Potential of Waste Activated Sludge The present invention relates to a method for measuring the biochemical methane potential of waste activated sludge, and more specifically, to a method for measuring the biochemical methane potential of waste activated sludge that provides quantitative criteria for the effective volume of the reactor and the daily biogas production in a biochemical methane potential (BMP) test using an inoculum that has undergone a pre-culture process. The use of fossil fuels and other non-renewable energy sources is on the decline worldwide. Biogas production utilizing anaerobic digestion to convert organic waste, including sewage sludge, into energy is one of the most feasible methods for achieving sustainable development. Anaerobic digestion is generally widely used for the treatment of industrial wastewater, livestock wastewater, and sewage sludge, and is an environmentally friendly technology for the treatment of various organic wastes (Gao et al., 2023). Anaerobic digestion is a biochemical treatment method that converts organic matter into methane through hydrolysis, acidogenesis, and methaneogenesis stages using microorganisms, including bacteria and archaea, under oxygen-free anaerobic conditions (Xu et al., 2018; Ye et al., 2024). Microorganisms involved in anaerobic digestion are classified into acid-producing bacteria, acetate-producing bacteria, and methanogens (Wang et al., 2018). Recently, research is underway to analyze the state of digesters through microbial communities by analyzing 16S rRNA gene data (Pei et al., 2022). Biochemical methane potential (BMP) testing is a method to determine the methane potential and biodegradability of organic waste, such as sewage sludge, in anaerobic digestion batch reactors. BMP testing requires detailed configuration of various conditions, such as total volume, working volume, maximum pressure limit, pre-incubation time, and overhead pressure measurement and release (OHPMR) frequency (Himanshu et al., 2017). However, there is no single universally used standard method, and only various guidelines have been presented (Himanshu et al., 2017). Examples include the IWA's ABAI (anaerobic biodegradation, activity and inhibition) method (Angelidaki et al., 2009), the VDI (verein deutscher ingenieure) 4630 guideline (2006), and new ABAI guidelines, which provide standards for substrate, sieving, pre-incubation, inoculum activity, mixing, blanks and controls, and experimental setup. However, the reproducibility of BMP tests has shown significant errors, with differences of more than twofold for the same samples. Therefore, it is necessary to propose a quantitative standard method for BMP testing. In BMP testing, the inoculum requires pre-incubation (starvation) to deplete remaining biodegradable organic material. Pre-incubation must be carried out under conditions identical to those of the inoculum reactor and must continue until biogas production is significantly reduced. Pre-incubation is performed until biogas production is minimized; while this duration is generally 2 to 5 days, some studies have reported durations ranging from a minimum of 1 day to a maximum of 14 days (Bella & Rao, 2022; Kabakci et al., 2024). However, depending on the type of wastewater/waste and reactor conditions, pre-incubation of the inoculum may need to be extended to minimize biogas generation. Therefore, it is difficult to establish a standard for pre-incubation based on duration. Consequently, there is a need for quantitative criteria regarding pre-incubation. Accordingly, the inventors have made diligent efforts to solve the above problem and have completed the present invention by confirming that when quantitative criteria are presented by considering the working volume (mL) of the reactor and the daily biogas production (mL/day) as standards for pre-culture in a BMP test using an inoculum that has undergone a pre-culture process, satisfactory and reliable reproducibility is realized in the cumulative biogas production test. FIG. 1 is a diagram showing the maximum, minimum, and coefficient of variation values of cumulative and daily biogas production in a pre-culture and biochemical methane potential test according to one embodiment of the present invention. FIG. 2 is a diagram illustrating the relative distribution of bacterial and archaea sequences in a 16S rRNA gene library for an inoculum and a pre-culture inoculum of (a) a bacterial phylum and (b) an archaeal family according to one embodiment of the present invention. FIG. 3 is a diagram illustrating the cumulative biogas production measured and predicted using modified Gompertz and logistic models in (a) pre-culture and (b) biochemical methane potential tests according to one embodiment of the present invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by a skilled expert in the art to whi