Increase of protein removal efficiency during acidogenesis of food waste recycling wastewater using crude extracts from pineapple wastes

Abstract

In this study, a novel approach was introduced that uses pineapple wastes as an additive to improve protein degradation and volatile fatty (VFA) acid production. The objectives were to (1) investigate the effects of addition of crude extracts from pineapple wastes (CEPW) on the protein degradation and VFA production, (2) find the optimal conditions where the protein removal efficiency and VFA production were maximized within the practical design boundary, and (3) examine the effect of CEPW addition on the bacterial community structure. The proteolytic activity of CEPW was clearly visualized using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the effective range of dosage was determined to be 1.63−6.53 casein digestion units (CDU)/mg protein. Response surface methodology was used to approximate the protein removal efficiency, with regard to the independent variables (1.63 ≤ [CPEW] ≤ 6.53 CDU/mg protein, 6 ≤ pH ≤ 8, 30 ≤ TOP ≤ 45 °C). The maximum protein removal efficiency was estimated to be 47.2% at 6.53 CDU/mg protein, pH = 6.9, and TOP = 36.6 °C. Ion Torrent analysis revealed that the families Porphyromonadaceae and Pseudomonadacea became dominant when CEPW was added; when it was not added, only the Pseudomonadacea proliferated, and protein removal was not significant.