Recovery ratio and quality of an agricultural bio-stimulant and semi-refined carrageenan co-produced from the fresh biomass of Kappaphycus alvarezii with respect to seasonality

Abstract

In general, to date, the majority of cultivated, dried biomass of Kappaphycus spp. has been used for the manufacture of refined (RC) or semi-refined carrageenan (SRC) on a commercial scale. However, the present study was focused on the production of SRC using wet fibrous residue left over after an agricultural bio-stimulant was extracted from the fresh biomass of Kappaphycus alvarezii in the manner of a biorefinery operation. The investigation examined the recovery ratio and quality of both bio-stimulant and SRC from the fresh biomass of K. alvarezii farmed on the Tamil coast of India for two consecutive seasons. This study was conducted on a large, pre-commercialization pilot-scale, i.e. 10.0 t of fresh biomass of K. alvarezii was crushed in each batch and a total 10 batches were made, each month during 2012 and 2013. The total recovery of the agricultural bio-stimulant and SRC from 1.0 t of fresh material processed at different seasons ranged from 19.58–23.69 dry kg (average 21.09 ± 1.35 kg) and 24.27–41.61 dry kg (average 31.75 ± 6.99 kg) respectively with a moisture content of 934.70–956.15 kg (average 947 ± 6.17 kg). The economics of conversion of fresh seaweed into agricultural bio-stimulant and SRC through MUZE (multi-stream, zero-effluent) process was far better as compared to conversion of dry weed into SRC alone through conventional methods, i.e. 1.0 t FS (Fresh seaweed) yielded a net profit of 224.14 US$ through multi- stream processing, whereas its dry-weed equivalent produced only 118.34 US$. The present investigation concluded that the fresh biomass of K. alvarezii can be used to co-produce agricultural bio-stimulants with a good efficacy and provide a relatively low yield of SRC with medium gel strength.