A sustainable organic liquid fertilizer and slurry fertilizer made from tilapia biofloc sludge.

Abstract

An organic fertilizer composition, referred to herein as fEx, derived from Tilapia biofloc sludge, consisting of essential micronutrients such as nitrogen (N), phosphorus (P2O5) and potassium (K2O), as well as micronutrients including calcium (Ca), iron (Fe), zinc (Zn), manganese (Mn), copper (Cu) and boron (B), and a high population of beneficial microorganisms, the fertilizer being formulated in both liquid and sludge form to promote plant growth, soil fertility and microbial diversity.

Description

Technical field of expertise:

[0001] The present invention relates to the field of sustainable agriculture and the production of organic fertilizers. In particular, it relates to the formulation and use of an organic bio-fertilizer obtained from nutrient-rich tilapia biofloc sludge, which aims to improve plant productivity, soil fertility, and microbial health through environmentally friendly waste recycling methods. Background of the invention;

[0002] The increasing demand for food security has led to the overuse of synthetic fertilizers in modern agriculture. While these fertilizers offer rapid nutrient availability, they contribute significantly to soil degradation, water pollution, and the loss of microbial diversity. At the same time, the aquaculture industry produces enormous quantities of nutrient-rich waste, particularly in biofloc fish farming systems, where the sludge that accumulates at the bottom of the tank remains largely unused. This sludge, rich in organic matter and minerals such as nitrogen, phosphorus, potassium, calcium, and trace elements, poses a major environmental disposal challenge.

[0003] Biofloc aquaculture technology, particularly in tilapia farming, creates a microbial ecosystem where feed residues, fish excrement, and biofloc particles combine to form a dense sludge. Traditional disposal of this sludge can lead to eutrophication of nearby waters. However, this same waste material holds enormous potential as a nutrient source for agriculture when properly processed and stabilized.

[0004] Existing organic fertilizers such as compost, vermicompost, or fish emulsions offer moderate nutrient levels but require lengthy preparation times and often exhibit an uneven microbial balance. Therefore, there is a need for a scientifically optimized, ready-to-use organic fertilizer derived from aquaculture waste that not only provides macro- and micronutrients but also promotes soil microbial activity, thereby increasing sustainable agricultural productivity.

[0005] The present invention fills this gap with a high-quality organic liquid fertilizer and slurry fertilizer derived from tilapia biofloc sludge. The formulation promotes circular waste management, supports soil regeneration, and aligns with the goals of ecological sustainability by transforming waste into a valuable agricultural input. Objectives of the invention: 1. To develop an organic fertilizer from tilapia biofloc sludge that recycles aquaculture waste into a nutrient-rich agricultural product. 2. To provide a formulation that exists in both liquid and sludge form and is suitable for various plant and soil conditions. 3. To improve plant growth, biomass and chlorophyll content while maintaining soil microbial diversity. 4. To provide a cost-effective and environmentally friendly alternative to chemical fertilizers. 5. A scalable process that can be adapted for community-based aquaponics and aquaculture systems should be established. Summary of the invention:

[0006] The invention, entitled "fEx - A Sustainable Organic Fertilizer from Tilapia Biofloc Sludge," introduces an innovative and environmentally conscious approach to the production of organic fertilizers by transforming nutrient-rich biofloc sludge from tilapia aquaculture into a high-quality liquid and slurry-like organic fertilizer. The central concept of this invention lies in the circular use of aquaculture waste, transforming what has traditionally been considered an environmental pollutant into a valuable agricultural input that enriches soil fertility, increases plant productivity, and promotes microbial diversity. The fertilizer, called fEx, represents a significant advancement in sustainable agriculture by bridging the gap between aquaculture and organic farming systems through an integrated waste-to-nutrient model.

[0007] The invention utilizes the potential of biofloc aquaculture waste, a complex mixture of microbial biomass, uneaten feed, and organic residues that accumulates at the bottom of tilapia culture tanks. This sludge is typically rich in macronutrients such as nitrogen (N), phosphorus (P₂O₅), potassium (K₂O), and calcium (Ca), as well as important micronutrients such as iron (Fe), zinc (Zn), and manganese (Mn). The innovative process developed in this invention involves the collection, stabilization, and conversion of this sludge into a biologically active fertilizer. The process begins with the systematic collection and separation of biofloc sludge, which is then subjected to microbial stabilization under controlled aerobic conditions. This ensures the elimination of undesirable anaerobic decomposition and the proliferation of beneficial microorganisms.The stabilized material is then processed into either a liquid fertilizer or a slurry fertilizer, depending on the intended agricultural application.

[0008] The liquid formulation of fEx is characterized by a balanced pH value of approximately 7.3, an electrical conductivity of 1.78 mS / cm and a microbial load of 8 × 10 5 CFU / mL. It contains significant nutrient concentrations, including 448 ppm nitrogen, 446 ppm phosphorus, 50 ppm potassium, and 933 ppm calcium, providing plants with an immediate food source when used as a foliar fertilizer or via drip irrigation. The sludge formulation, on the other hand, is more concentrated, with nitrogen levels of 823 ppm and phosphorus levels of 2871 ppm, along with an impressive microbial count of 5.3 × 10 7 CFU / g, which makes it suitable for direct soil application and compost enrichment.

[0009] Field and laboratory evaluations confirm the efficacy of fEx in promoting plant growth and soil health. Controlled experiments conducted on red amaranth (Amaranthus cruentus) and dill (Anethum graveolens) showed a remarkable increase in shoot and root length, leaf number, and chlorophyll content in plants treated with fEx compared to untreated controls. Chlorophyll content in fEx-treated amaranth plants reached 1,106 mg / g compared to 0.935 mg / g in the control samples, indicating improved photosynthetic activity. Biomass studies showed further significant improvements, with treated plants exhibiting up to 60% higher wet and dry weight accumulation.These results show that fEx not only provides essential nutrients but also improves microbial activity in the soil, leading to higher nutrient uptake efficiency and overall better plant vitality.

[0010] Beyond its agricultural benefits, fEx has enormous environmental and economic significance. By utilizing biofloc sludge, the invention effectively addresses the problem of waste disposal in aquaculture systems and reduces the risk of water pollution and eutrophication. At the same time, it offers a cost-effective and renewable fertilizer alternative to synthetic chemical fertilizers, the production of which often involves energy-intensive and environmentally damaging processes. The invention aligns with global sustainability goals by promoting resource efficiency, waste prevention, and the principles of a circular bioeconomy.

[0011] Essentially, fEx represents a scientifically validated, environmentally friendly, and scalable innovation capable of transforming aquaculture waste into a high-quality organic fertilizer. It promotes plant growth, soil fertility, and microbial balance while significantly reducing environmental impact. This integration of aquaculture byproducts into agricultural productivity cycles not only strengthens the link between aquatic and terrestrial food systems but also paves the way for a new generation of bioenriched fertilizers that are safe, sustainable, and economically viable for farmers worldwide. Detailed description of the invention

[0012] The present invention, entitled "A Sustainable Organic Fertilizer from Tilapia Biofloc Sludge," represents a groundbreaking advance in organic fertilizer technology and sustainable waste management. The invention introduces a unique process for converting nutrient-rich biofloc sludge, a by-product of tilapia aquaculture, into a biologically active and environmentally friendly organic fertilizer. This fertilizer, formulated in both liquid and sludge forms, improves soil fertility, promotes plant growth, and contributes to the sustainable recycling of aquaculture waste into agricultural productivity.The development of fEx addresses several critical challenges facing modern agricultural and aquaculture systems, including the overuse of chemical fertilizers, soil degradation, and environmental hazards associated with the disposal of fish farm waste.

[0013] The conceptual basis of the invention lies in the approach of the circular bioeconomy, in which waste products of one system serve as resource input for another system. Tilapia aquaculture systems utilizing the Biofloc method generate significant amounts of organic sludge as a byproduct. This sludge consists of fish excrement, uneaten feed particles, microorganisms, and detritus suspended in a complex microbial ecosystem. If left untreated, the sludge can lead to environmental pollution through eutrophication and anaerobic decomposition. However, when properly stabilized, this same material is an excellent source of plant nutrients and beneficial microorganisms. The invention takes advantage of this fact by processing Biofloc sludge to create a ready-to-use fertilizer that is both rich in essential nutrients and biologically active.

[0014] The preparation process begins with the systematic collection of biofloc sludge from aquaculture tanks. These tanks, in which tilapia fish are raised under controlled aeration, naturally produce microbial flocs that aggregate organic material. The sludge that settles at the bottom is regularly collected and separated from the water. This material then undergoes a filtration step to remove larger particles and excess moisture. The filtered sludge is partially dried at ambient conditions to achieve a manageable consistency suitable for further processing.

[0015] The sludge then undergoes a crucial microbiological stabilization phase. This step is essential for transforming the raw, unstable sludge into a stable organic medium. During stabilization, the sludge is subjected to continuous aeration, which suppresses anaerobic microbial activity responsible for unpleasant odors and methane production. Beneficial aerobic bacteria and actinomycetes present in the sludge multiply rapidly under these conditions, resulting in the natural bioactivation of the material. The stabilization phase typically lasts until the sludge has a neutral odor and a stable pH close to neutral (approximately 7.0–7.3). This phase ensures that the final product contains a dense and beneficial microbial population capable of improving the soil microflora after application.

[0016] The stabilized sludge can then be processed into two different formulations, depending on the intended agricultural application: a liquid formulation and a sludge formulation. For the liquid fEx, the stabilized sludge is diluted with clean water in controlled proportions to achieve a liquid consistency suitable for foliar spraying and fertigation. The solution is then filtered through fine mesh sieves to remove suspended particles and ensure compatibility with irrigation systems. The resulting liquid formulation has the following properties: a pH of 7.3, an electrical conductivity (EC) of 1.78 mS / cm, a total dry matter content of 1.03%, and a microbial load of approximately 8 × 10⁻⁶. 5CFU / mL. The nutrient analysis of the liquid formulation shows 448 ppm nitrogen, 446 ppm phosphorus (P2O5), 50 ppm potassium (K2O) and a high calcium content (933 ppm), with trace amounts of essential micronutrients such as Fe, Zn, Mn, Cu and B. This liquid version is particularly advantageous for farmers who prefer foliar application or fertigation for immediate nutrient uptake.

[0017] In contrast, fEx's sludge formulation is designed for soil amendment and base fertilization. The stabilized sludge is partially concentrated through dehydration to obtain a thick, semi-solid form. These sludges retain a significantly higher nutrient density, including 823 ppm nitrogen, 2871 ppm phosphorus (P₂O₅), 240 ppm potassium (K₂O), and a microbial load of approximately 5.3 × 10⁻⁶ 7CFU / g. The high microbial density in the slurry formulation makes it ideal for improving microbial activity in the soil, accelerating the decomposition of organic matter, and improving soil structure. It can be applied directly to fields during tillage or mixed with compost and manure to increase nutrient availability.

[0018] The production process is simple, scalable, and environmentally friendly. All preparation can be carried out near aquaculture facilities, allowing farmers to convert fish waste into fertilizer without specialized equipment. The process involves no chemical additives, ensuring the product remains completely organic. After production, both the liquid and sludge formulations are packaged in airtight containers under aseptic conditions to maintain microbial viability.

[0019] The scientific validation of fEx was carried out through laboratory tests and controlled field trials. The nutrient composition and microbial profile were analyzed in certified laboratories such as ANALAB, Solapur, and Varsha Agro Clinic, Solapur. The analyses confirmed that fEx contains not only macronutrients (N, P, K) but also secondary nutrients (Ca, Mg, S) and trace elements (Zn, Fe, Mn, Cu, B, Mo, and Si), which play a crucial role in plant metabolism. Furthermore, the high microbial count demonstrates the product's biological activity, distinguishing it from conventional fertilizers that do not contain living microbial communities.

[0020] To evaluate the efficacy of fEx, experimental trials were conducted on two plants: red amaranth (Amaranthus cruentus) and dill (Anethum graveolens). Both plants were grown under controlled environmental conditions, with one group treated with fEx and the other serving as a control. Growth parameters were monitored at regular intervals (7, 14, 21, and 28 days). The results showed that, compared to the control group, the treated plants exhibited significantly greater shoot and root lengths, a greater number of leaves, and improved chlorophyll content. On day 28, fEx-treated amaranth plants reached a shoot length of 21.6 cm compared to 14.3 cm in the control group. Similarly, the treated dill plants showed marked improvements in root growth and leaf development.

[0021] Biomass analysis further confirmed the fertilizer's effectiveness. Treated amaranth plants showed wet biomass values ​​of 1.65 g and dry biomass values ​​of 0.564 g, compared to 1.123 g and 0.534 g, respectively, in the control group. Dill plants showed even more pronounced differences, with treated samples reaching a fresh biomass of 0.118 g compared to 0.043 g in the controls. The increased chlorophyll content (1.106 mg / g in the treated amaranth compared to 0.935 mg / g in the control) reflects improved photosynthetic efficiency resulting from better nutrient uptake facilitated by fEx.

[0022] The mechanism of action of fEx is dual – nutritional and biological. Nutritionally, it provides plants with readily available macronutrients and trace elements essential for growth and metabolic functions. Biologically, the microbial populations present in fEx contribute to soil health by improving the decomposition of organic matter, nitrogen fixation, and phosphate solubility. These microorganisms create a dynamic rhizospheric environment that enhances nutrient availability and supports root growth. Over time, the continuous application of fEx improves the organic carbon content of the soil, increases water retention capacity, and promotes sustainable soil fertility.

[0023] The environmental significance of the invention is equally profound. Traditional aquaculture operations face the challenge of managing biofloc sludge, which, when released into natural waters, contributes to nutrient pollution and oxygen depletion. By diverting this sludge to fertilizer production, the invention offers an environmentally friendly solution for the disposal of aquaculture waste. This integration of fish farming and plant cultivation forms a closed system that minimizes waste and maximizes resource efficiency. It directly supports global sustainability goals such as responsible consumption and production (SDG 12) and life below water (SDG 14).

[0024] From an economic perspective, fEx offers a cost-effective alternative to chemical fertilizers. The raw material, biofloc sludge, is readily available in aquaculture facilities without additional costs, and the production process requires minimal infrastructure. Small-scale fish farmers can implement the process to generate additional income while simultaneously reducing fertilizer expenditures.

[0025] Furthermore, organic farmers can benefit from an environmentally friendly, nutrient-balanced fertilizer that meets the standards of organic certification.

[0026] The practical applications of fEx extend beyond vegetable cultivation. It can be used effectively in orchards, floristry, nurseries, and field crops. The liquid formulation is ideal for hydroponic systems and greenhouse cultivation, while the slurry version is well-suited for soil-based farming. It can be mixed with other organic additives such as compost or biochar to promote soil improvement. Regular application of fEx enhances the biological activity of the soil and ensures long-term agricultural productivity without the negative environmental footprint associated with synthetic fertilizers.

[0027] Regarding stability and storage, both formulations retain their efficacy over extended periods when stored under cool, shaded conditions. The microbial population remains viable for several months due to the presence of natural organic material in the medium, which acts as a substrate. The formulations do not produce harmful odors or cause phytotoxic effects, ensuring safe handling and application.

[0028] In conclusion, the present invention offers a scientifically validated, environmentally responsible, and economically viable solution for sustainable agriculture. By converting tilapia biofloc sludge into the dual-form fertilizer fEx, the invention integrates waste management and plant nutrition into a unified ecological model. It promotes soil regeneration, reduces reliance on chemical fertilizers, and contributes to long-term agricultural sustainability. fEx exemplifies how biotechnology and circular economy principles can work together to transform waste into prosperity. The development of this fertilizer represents not only a technological innovation but also a step toward global environmental responsibility by providing farmers, aquaculture companies, and environmental agencies with a pathway to collaborate in creating resilient and regenerative agricultural systems for the future.

Claims

[1] An organic fertilizer composition, referred to herein as fEx, derived from Tilapia biofloc sludge, consisting of essential micronutrients such as nitrogen (N), phosphorus (P2O5) and potassium (K2O), as well as micronutrients including calcium (Ca), iron (Fe), zinc (Zn), manganese (Mn), copper (Cu) and boron (B), and a high population of beneficial microorganisms, wherein the fertilizer is formulated in both liquid and sludge form to promote plant growth, soil fertility and microbial diversity. [2] Fertilizer composition according to claim 1, wherein the liquid formulation has a pH value in the range of 7.0 to 7.5, an electrical conductivity of about 1.78 mS / cm and a microbial population density of at least 8 × 10 5 It has a CFU / mL value, making it suitable for foliar fertilization and drip irrigation applications in horticulture and field crops. [3] Fertilizer composition according to claim 1, wherein the sludge formulation has nutrient concentrations of at least 800 ppm nitrogen, 2800 ppm phosphorus (P2O5) and 240 ppm potassium (K2O), together with a microbial number of approximately 5.3 × 10 7 CFU / g, which enables its use as a base fertilizer or compost enrichment additive to improve soil fertility. [4] Fertilizer composition according to claim 1, wherein the application of the fertilizer to plants results in a measurable improvement in growth parameters including shoot and root growth, number of leaves, chlorophyll content and total biomass yield, thereby improving plant productivity and soil quality compared to untreated control samples. [5] Fertilizer composition according to any of the preceding claims, wherein the composition is derived entirely from renewable aquaculture waste sources and offers an environmentally sustainable and economically viable alternative to synthetic fertilizers, promoting the circular economy and being consistent with sustainable agricultural practices.