Original article: fermented pulp and paper bio-sludge as feed for black soldier fly larvae

Abstract

This study evaluates the use of fermentation to increase nutrient availability in pulp and paper bio-sludge (PPBS) as feed for black soldier fly larvae (BSFL). Rearing of BSFL on fermented PPBS was carried out in a climate chamber in order to assess nutrient availability and larvae survival and growth. The PPBS used came from a chemo-thermomechanical pulp/groundwood pulp mill. The PPBS was fermented at 35 °C and 55 °C, respectively, at initial pH of 10. The effects of sediment and liquid from fermented PPBS on larvae dry weight, survival rate until the prepupae stage, bioconversion, and reduction rate of PPBS were measured. The bioconversion of the liquids (4.1–6.6%) was substantially higher than for both the sediments and untreated PPBS (≤ 0.4%). The survival rate, on the other hand, was substantially lower (26.3–30.9 %) than for the sediments and untreated PPBS (49.5–52.6%). Neither the sediments nor the liquids had significant effects on the larvae weight or on the PPBS reduction rate. The sediments had no significant effect on the survival rate or the bioconversion. This study demonstrates that fermentation dissolves a part of the PPBS and that dissolved substances in the fermentation liquid readily convert to larvae biomass. However, the bulk of the lignocellulose is not dissolved, and most of PPBS nutrients remain unavailable for growth of the larvae. Further research should focus on improved pretreatment of PPBS to increase availability of nutrients and thereby improve the feasibility of BSFL as a recycling method for PPBS.

Determination of lipid requirements in black soldier fly through semi-purified diets

“…Composting, however, would not valorise the remaining nutrient content of the organic material that is used for it. The BSFL breeding, on the other hand, can turn waste into valuable protein for the feed industry 9 , 10 . The insect protein industry is currently facing two main challenges that still prevent it to become competitive on the market: the need to upscale and the regulatory barriers 11 .…”

The effect of pH, temperature, and inoculum on the fermentation of pulp and paper biosludge: increasing the nutrient availability for rearing of black soldier fly larvae

“…A VFA concentration of 26 g L −1 produced the heaviest larvae (17.8 mg) compared to 0 and 15 g L −1 (7.8 mg and 9.4 mg, respectively) [19]. The concentration of VFA obtained in this study is too low to obtain a substantial increase in the weight of larvae [8]; thus, further research on improved fermentation of PPBS is needed to increase the concentration of VFA. However, the acetic acid fraction of the total VFA obtained, i.e., 68% at 35 °C and 63% at 55 °C (Fig.…”

“…Chemical and physical methods of improving nutrient availability as well as the technological methods to achieve it are summarized by Norgren et.al. [8]. Improving nutrient availability by anaerobic digestion is one method of pretreatment that has been discussed recently [8][9][10][11][12][13][14][15][16].…”

“…[8]. Improving nutrient availability by anaerobic digestion is one method of pretreatment that has been discussed recently [8][9][10][11][12][13][14][15][16]. Disintegration, hydrolysis, acidogenesis (also called fermentation), acetogenesis, and methanogenesis are the steps in anaerobic digestion [17]: large organic compounds are first broken down into monomers, then further converted by microorganisms to volatile fatty acids (VFAs), alcohols, carbon dioxide, hydrogen, and methane [18].…”