ABSTRACT
Ameliorative effects of sheep slaughterhouse waste-derived soil amendments (struvite, blood meal, bone meal) were explored and quantified by a series of comparative greenhouse trials. A scoring matrix system was developed for 25 different test plants using 300 agricultural measurements obtained for three basic growth parameters (fresh-dry plant weights and plant heights) and four different fertilizer sources including solid vermicompost. More than 70% of NH4+-N recovery from sheep slaughterhouse wastewater was achieved using a chemical combination of MgCl2.6H2O + NaH2PO4.2H2O, a molar ratio of Mg2+:NH4+-N:PO43-P = 1.2:1:1, a reaction pH of 9.0, an initial NH4+-N concentration of 240 mg/L, and a reaction time of 15 min. According to SEM micrographs, surface morphology of struvite exhibited a highly porous structure composed of irregularly shaped crystals of various sizes (11.34-79.38 µm). FTIR spectroscopy verified the active functional groups on the proximity of all fertilizer sources within the spectral range of 500-3900 cm-1. TGA-DTG-DSC thermograms of struvite revealed that the mass loss occurred in two temperature regions and reached a maximum mass loss rate of 1.63%/min at 317 °C. The average percentages of increase (57.55-100.62%) and performance points (69-79) corroborated that the fertility value of struvite ranked first on average in cultivation of the analyzed plant species. Findings of this agro-valorization study confirmed that sheep slaughterhouse waste-derived fertilizers could be a beneficial way to promote bio-waste management and environmentally friendly agriculture.
Subject(s)
Fertilizers , Soil , Abattoirs , Animals , Fertilizers/analysis , Magnesium Compounds/chemistry , Phosphates/chemistry , Phosphorus , Sheep , Struvite/chemistry , Wastewater/chemistryABSTRACT
The present analysis was conducted as the first research to assess the techno-economic viability of the value-added by-products (struvite, blood meal, bone meal, and raw sheepskin) from a medium-scale sheep slaughterhouse facility with a slaughtering capacity of 300 sheep per day. For this aim, a comparative technical and economic feasibility analysis was performed to assess the synergistic use of slaughterhouse-oriented rendering wastes and struvite recovery from real sheep abattoir effluent within the framework of detailed cost breakdown, break-even point, and payback period analyses. The experimental findings clearly showed that under the optimal conditions (chemical combination of MgCl2.6H2O + NaH2PO4.2H2O, a molar ratio of Mg2+:NH4+-N:PO43--P = 1.2:1:1, a reaction pH of 9.0, an initial ammonium concentration of 240 mg NH4+-N/L, and a reaction time of 15 min), struvite precipitation could effectively remove about 73%, 64%, 59%, and 82% of NH4+-N, TCOD, SCOD, and color, respectively, from the real sheep slaughterhouse waste stream. Based on various up-to-date techno-economic items considered within the break-even point analysis, the sheep slaughterhouse facility was estimated to achieve the targeted net income (100/day) for any selling prices of 1041.30/ton, 640.05/ton, 263.72/ton, and 1.012/hide, respectively, for struvite, blood meal, bone meal, and raw sheepskin. Steel construction and chemicals were determined as the most costly components for CAPEX (capital expenditures) and OPEX (operating expenditures), respectively, and selling prices of bone meal and raw sheepskin were found to be the most critical income items on the profitability of the slaughterhouse facility. Co-monetary assessment of the struvite process and valorized compounds corroborated the economic viability of the proposed project with the payback periods of about 6.3 and 5.5 years, respectively, for the current market and the profit-oriented conditions without subsidy. The findings of this feasibility analysis, as the first of its own, could be used as guideline for simplifying the decision-making with regards to the feasibility of similar facilities and commercialization of profitable by-products.
