Re-cultivation of dry microalgal-bacterial granular sludge

Abstract

Deepening the research on the storage and transportation of the microalgal-bacterial granular sludge (MBGS) will help its engineering application. Herein, re-cultivation of naturally dried MBGS was investigated. The results showed that the MBGS could be re-cultivated in 18 days in both aeration and non-aeration systems. Notably, the aeration system could facilitate granulation with superiority in both granule size and settleability of MBGS over the non-aeration system. The ammonia removal by re-cultivated MBGS under aeration condition was dramatically higher than non-aeration condition. In addition, the microbial community of MBGS had evolved dramatically after re-cultivation. Furthermore, the primary mechanism for the granule growth and the formation of new granule during the dry MBGS re-cultivation under aeration condition was deduced to be microbial coaggregation (e.g. Acinetobacter ), whereas under non-aeration condition it might be ascribed to the microbial mobility. This study is expected to provide insights into the storage of MBGS and the restart of MBGS process . • Re-cultivation of dried microalgal-bacterial granular sludge (MBGS) was studied. • Dried MBGS could be recovered in structure and properties within 18 days. • Aeration facilitates granular settleability, size and ammonia removal of MBGS. • Microbial community of MBGS had evolved dramatically after the re-cultivation. • The possible mechanisms for re-cultivation of dry MBGS were put forward.