Hydrogen as a quick indicator of organic shock loading in UASB

Abstract

This study investigates the influence of organic shock loading on H2 production in an upflow anaerobic sludge bed (UASB) reactor. An esterification wastewater produced from a polyethylene terephthalate (PET) manufacturing plant was applied; the major organic pollutants are ethylene glycol and acetaldehyde. Experiments of two influent modes were performed here: a continuous-flow mode with a step input of shock loading and a batch mode with a pulse input of shock loading. Results of the continuous-flow experiments indicate that biogas production parameters such as H2 concentration and biogas production rate are more sensitive than water quality parameters such as pH, ORP, COD and TOC. In particular, H2, increasing by 140% within 1 hour, is a very important index upon the organic shock loading. It changes from 120 ppm to over 600 ppm as the organic loading rate increases from 4.4 to 13.2 kgCOD/m3·day through 4 hours of shock loading. Experiments of the batch shock loading with different pulse dosagesof ethylene glycol, acetaldehyde and the raw wastewater were also investigated. The amount of H2 production increased in proportion to an increase of organic load. Furthermore, the sequence of H2 production among the three types of shock loading is acetaldehyde> ethylene glycol> raw wastewater. To sum up, H2 shows a faster response rate than the other parameters. Therefore, H2 can be adopted as an important parameter for organic shock loading in UASB.