Laccase-assisted bioremediation reactor for accelerated lignin degradation during composting

Abstract

An enzymatic bioremediation reactor device for the accelerated composting of lignocellulose material, consisting of a sealed, insulated container, a mechanical pretreatment unit and an automated laccase enzyme supply system.

Description

Application area of ​​the invention

[0001] The present invention relates to a special, controlled bioremediation device for accelerating the enzymatic degradation of lignin in organic waste, in particular rice hulls, for rapid and high-quality composting. Background of the invention

[0002] The utilization of agricultural waste, particularly rice hulls, presents a significant ecological and logistical challenge due to their high resistance to degradation. Rice hulls are rich in lignin, a complex polymer that forms a structural barrier and severely hinders microbial and fungal degradation, extending the composting process to several months. This slow decomposition limits the widespread use of rice hulls as a high-quality soil improver. The resulting low-quality compost often exhibits poor nutrient availability and a low humus content. Conventional composting methods are energy- and time-intensive and do not achieve optimal lignin degradation.Therefore, there is an urgent need for an efficient, accelerated composting system that can overcome lignin resistance and thus quickly and sustainably transform a waste product in large quantities into a valuable, nutrient-rich soil improver. Summary of the invention

[0003] The present invention relates to a novel enzyme composting reactor (ECR) system designed as a continuous or batch device for the accelerated decomposition of lignocellulosic biomass, particularly rice hulls. The system comprises a mechanical pretreatment unit for particle size reduction, an integrated liquid handling system, and an insulated, monitored reaction vessel. The device is designed to precisely control essential environmental parameters, such as temperature, humidity, and pH, for maximizing the activity of the laccase enzyme used to catalyze lignin degradation. The ECR system offers a targeted and highly efficient solution for overcoming the compostability resistance of rice hulls.

[0004] The primary function of the ECR system is the accelerated hydrolysis of lignin, drastically reducing composting time from months to just a few weeks. By precisely controlling and maintaining optimal conditions for laccase activity (e.g., pH 4.5–5.5, temperature 25–35 °C), the system achieves superior lignin reduction. This accelerated degradation results in high-quality compost with significantly higher levels of available nitrogen, phosphorus, and potassium, as well as an increased proportion of stable humus. The system thus offers a sustainable, highly efficient, and scalable method for resource recovery and waste management. Detailed description

[0005] The invention describes a system for accelerated bioremediation, hereinafter referred to as the reaction vessel (RV), optimized for the enzymatic degradation of lignocellulose. The overall system is designed to convert agricultural waste, in particular rice hulls, into high-quality compost through controlled laccase activity within a significantly shortened timeframe.

[0006] The RV system begins with a mechanical pretreatment unit consisting of industrial crushers or hammer mills. This unit is essential for increasing the surface area of ​​the rice hull feedstock. This is a prerequisite for efficient enzyme penetration and subsequent degradation, and ensures a uniform material composition before it enters the main reaction chamber.

[0007] The main reaction vessel is a sealed, insulated chamber made of robust, corrosion-resistant material. It features an integrated mixing mechanism, such as rotating paddles or augers, which ensures the homogeneous distribution of the rice hulls and the laccase solution, as well as uniform thermal conditions throughout the composting biomass.

[0008] A crucial component is the enzyme delivery subsystem (EDS), which stores and precisely injects the laccase solution. This subsystem includes a buffered reservoir for the laccase enzyme, typically derived from white-rot fungi such as Trametes versicolor or Pleurotus ostreatus, and a calibrated atomizing nozzle or dropper to ensure uniform distribution of the enzyme onto the pre-treated rice hulls.

[0009] The composting machine is controlled by a sophisticated environmental control system (ECS). This ECS uses a network of internal pH, temperature, and humidity sensors to continuously monitor the internal conditions of the compost mass and provide real-time feedback.

[0010] The ECS controls an internal heating element and a humidity spray system. The heating element ensures that the reaction temperature is maintained within the optimal enzymatic range of 25 °C to 35 °C to prevent thermal denaturation of the laccase while maximizing catalytic activity.

[0011] The ECS's humidity control function ensures precise water supply to guarantee optimal hydration and maintain a stable moisture content between 50% and 60%. This hydration level is crucial for enzyme mobility and microbial viability. Furthermore, the pH is actively adjusted as needed by adding buffer solutions via the EDS to maintain the optimal acidic range of 4.5 to 5.5 for laccase activity.

[0012] The precise, active control enabled by the device dramatically alters the reaction kinetics. By maintaining these specific environmental parameters, the system accelerates the laccase-catalyzed oxidation of lignin bonds and breaks down the complex polymer into smaller, more bioavailable fragments significantly faster than conventional, passive composting methods.

[0013] Respiration vessel (RV) processing, which typically occurs within 7 to 21 days, produces a high-quality intermediate product. The resulting material exhibits an improved carbon-to-nitrogen ratio and superior soil fertility properties due to the high degree of lignin removal, confirming the significant technical advantage of the integrated plant.

[0014] In summary, the $\text{ ECR}$ apparatus functions as a highly efficient and sustainable industrial device that provides the necessary controlled environment and targeted enzymatic action to rapidly convert difficult-to-degrade agricultural waste into a valuable and nutrient-rich soil improver.

Claims

[1] An enzymatic bioremediation reactor device for the accelerated composting of lignocellulose material, consisting of a sealed, insulated container, a mechanical pretreatment unit and an automated laccase enzyme supply system. [2] Device according to claim 1, further comprising an environmental control system with integrated sensors configured to continuously monitor and maintain the moisture content of the material between 50% and 60%. [3] Device according to claim 2, wherein the environmental control system is further configured to stabilize the internal material temperature between 25 °C and 35 °C and the pH value between 4.5 and 5.5 in order to optimize the laccase enzyme activity. [4] Device according to claim 1, wherein the laccase enzyme delivery system comprises a buffered reservoir and atomizing nozzles configured to precisely inject a laccase solution obtained from Trametes versicolor onto the pretreated lignocellulosic material.