A New Biofertilizer Formulation with Enriched Nutrients Content from Wasted Algal Biomass Extracts Incorporated in Biogenic Powders

Abstract

Raw algae waste naturally thrown on shores could pose serious threats for landfilling and its reuse for composting or further processing as added-value by-products require knowledge-based decisions and management for the sustainable development of local ecosystems. Raw marine waste containing salt (halite) and heavy metals that eventually accumulate in algae hamper their safe applicability in soil fertilization or in other exploitations. Here, the suitability of algal biomass for use as an environmentally safe fertilizer was investigated, thereby supporting sustainable coastal management. The simple extraction of the dry algal biomass of three abundant Mediterranean species, Enteromorpha intestinalis, Corallina elongata, and Gelidium pulchellum, in water containing sodium carbonate resulted in a greenish extract containing a reduced heavy metals content, and nutrients such as K+, PO43−, SO42−, NO3−, Ca2+, and Mg2+. UV-Vis and Raman techniques, including surface-enhanced Raman scattering (SERS), were employed for the fast evidencing of polyphenols, carotenoids, and chlorophylls in the extracts content, while E. intestinalis extract additionally exhibited polysaccharide signals. Heavy metals analysis showed that the major metals in the extracts were Fe, Ni, Zn, and Cu; however, their levels were an order of magnitude lower than in the dry biomass. The extracts also showed a mild antibacterial effect. The combination option of aqueous extracts with powdered crustacean shells to obtain a novel, eco-friendly, solid biofertilizer complex was further shown, which could be pelleted for convenient use. The immersion of solid biofertilizer pellets in water is accompanied by re-solubilization of the compounds originating from algae extracts, presenting the opportunity for dry storage and easier handling and land applicability. In summary, aqueous extracts of marine algae waste present an environmentally safe and attractive way to recycle excessive algal biomass and to formulate a new, eco-friendly biofertilizer complex.

Rapid and Application-Tailored Assessment Tool for Biogenic Powders from Crustacean Shell Waste: Fourier Transform-Infrared Spectroscopy Complemented with X-ray Diffraction, Scanning Electron Microscopy, and Nuclear Magnetic Resonance Spectroscopy

“…The proposed FTIR method can be easily used to evaluate the chemical composition of the waste biomaterial, which is in turn useful for decision-making regarding the development of advanced applications of biogenic powders such as pharmaceutical carriers, loaded powders with various fluids for new composite materials, adsorbents for environmental decontamination, and many others. Although this method cannot differentiate between crab species, it may be successfully applied in evaluating other categories of biogenic materials from seafood waste, such as oysters, snails, urchin shells, and shrimps, all consisting of calcite or calcite/aragonite, as main minerals and various amounts of organic materials.…”

“…Crustacean shells are currently viewed as food waste. These shells are rich in valuable natural compounds, most notably chitin, proteins, amino acids, and carotenoid pigments, − along with the well-known calcite biomineral. Proper and efficient management and further reuse of this biogenic raw material require a solid knowledge-based and well-developed analytical methodology, including data on structural and compositional analysis of crab shells resulted from aquaculture exploitation, seafood industry, and domestic seafood consumption.…”

“…The green crab, Carcinus aestuarii, is a locally exploited species in the Mediterranean, while its congenerous species Carcinus maenas is being exploited worldwide . Because of large global consumption, discarded crab shells present an unexploited recurrent resource with potential advanced applications of their compositional and ultrastructural features, which were earlier described by Roer and Dillaman and Santos and recently by Nekvapil et al − For instance, chitosan extracted from crab shells was used for construction energy storage units (batteries) and electrical double layer capacitor (EDLC) cells . The crab shell carbonate biocomposite was considered as a filler for automotive brake pads, as a steel coating material, as an organochlorine pesticide and textile industry dye removal agent, and as a template for high-performance capacitors .…”

“…The crab shell carbonate biocomposite was considered as a filler for automotive brake pads, as a steel coating material, as an organochlorine pesticide and textile industry dye removal agent, and as a template for high-performance capacitors . With global trends shifting toward a circular economy and with the emphasis on reusing and recycling waste, it is expected that a wider use will be found for crab shells in multiple industries. ,, …”

“…13 With global trends shifting toward a circular economy and with the emphasis on reusing and recycling waste, it is expected that a wider use will be found for crab shells in multiple industries. 2,4,14 Depending on the final aim of reusing, the steps in shell waste processing can roughly be divided into demineralization (removal of CaCO 3 ) and deproteinization (removal of proteins), which are applied depending on the class of the compound to be extracted. 15 An emerging concept of "shell biorefinery", which comprises sets of methods for crustacean shell refining, is pushing its way toward perspective applications.…”