The influence of chicken eggshell powder as a buffer on biohydrogen production from rotten orange (Citrus nobilis var. microcarpa) with immobilized mixed culture

Abstract

This research observed the influence of chicken eggshell on hydrogen production from anaerobic fermentation of rotten orange (Citrus nobilis var. microcarpa) using batch method at 36 °C and pH 7. Fermentation material were varied in several types, the first type was meat and peel of oranges with VS of 59.152 g.L−1 in A, B, C, and D compositions. The second type was orange meat added with peel (OMP) with VS of 36.852 g.L−1. The immobilized ingredients used in the experiment consisted of 2 % (w/v) alginate and active carbon with the ratio of 1:1. 3.2 g chicken eggshell powder was added to the first type of material (substrates A, B, C, and D). Results showed that pH during fermentation process using chicken eggshell as a buffer was constant at 5.5; however, without the use of chicken eggshell, the pH decreased to 3.8 and increased slightly before it stayed stable at 4.0. The total amount of gas produced in sample using the chicken eggshell was 46,35 mL.mg VS−1 and in sample produced without the eggshell, it was 3,4 mL.mg VS−1. The production of hydrogen in substrate that used chicken eggshell was 1,276 mL.gVS−1 in average on the first day. Meanwhile, for the substrate with no addition of chicken eggshell, the average production of hydrogen was 0,163 mL.gVS−1. The reduction of volatile solid (VS) in sample that used chicken eggshell was 24 %, while in sample produced without addition of chicken eggshell, the reduction was 12 %. The liquid compounds (VFA) produced in the fermentation using chicken eggshell were acetic acid and butyric acid. Meanwhile, without addition of chicken eggshell, the products were acetic acid, butyric acid, and propionic acid. This study shows that addition of chicken eggshell as a buffer effectively contributed to hydrogen production during fermentation of rotten oranges.