Bioreactors and Their Role in Hydroponic Farming

What are the implications of bioreactors in commercial hydroponics systems? Can they help alleviate the nutrient balancing acts of millions of gallons of solution commercial systems struggle with??

First, let’s give an overview of the topic at hand by addressing what hydroponic farming is. Commercial Controlled Environment Agricultural (CEA) hydroponic systems grow produce that is grown indoors using the hydroponics technique without the need for soil. These crops receive all of their nutrition through a nutrient solution that is delivered directly to their roots at the right temperature, with injected oxygen, and an appropriate pH. This method of growing is significantly faster as opposed to drawing the minerals required for growth from the soil through exudates and humic acids creating the environment for nutrient uptake.

Although there are other metabolic pathways involved in plant growth, water, light, and vital nutrients are the three major factors that drive plant growth. In conventional agriculture, the soil holds the plant in place and serves as a storage area for nutrients and water. By giving the plant's roots a nutrient-rich aqueous solution that keeps them hydrated and fed while additional lighting options simulate sunlight (CEA), a hydroponics system eliminates the need for soil and speeds up the growth cycle of the crops.

Now CEA and hydroponics systems have become increasingly popular in recent years due to the potential to provide fresh, high-quality yield with minimal environmental impact while utilizing less water than conventional farming, it has not come without any challenges. Maintaining the ideal nutrient balance in hydroponic systems can be challenging and at scale, the ability to manipulate the amount of water that has to be dosed and appropriately maintained has become a challenge. This has led to the development of Organic Bioreactors as a means of controlling nutrient levels in solution and improving plant growth.

Building a covered aerobic bioreactor to convert biowaste like poultry or cow manure or the produce or green material from the CEA system into benign plant food might be among the best alternatives to expensive synthetic fertilizer or composting. And, it provides plants with beneficial micronutrients not available in synthetics.

Today, given the cost of synthetic, supply chain insecurity, and inorganic fertilizers, with concerns about how these fertilizers are manufactured, many hydroponic farmers are looking for organic alternatives that can scale and be cost-effective. They usually turn to purchasing nutrient solutions or using a ready-batched solution. Both have their challenges.

Organic Bioreactors are essentially systems that use living organisms to convert nutrients into forms that can be easily taken up by plants. Microbial bioreactors are most commonly used in hydroponics systems. These systems use microorganisms, such as bacteria or fungi, to convert organic matter, root sheds, exudates, and other nutrients into plant-available nutrients. The microorganisms in the bioreactor break down organic matter through a process known as mineralization, which releases nutrients such as nitrogen (nitrite), phosphorus, and potassium. The nutrients are then absorbed by the plants through their roots, leading to faster growth and higher yields (nitrate). Nitrate is a nitrogen by-product of the nitrifying bacteria (Nitrospira) in a filter, substrate, or in solution.

What is aerobic fermentation?

There are two types of microorganisms that can convert raw biological waste such as manure or food waste into benign, ready-to-use, plant food. One type works best in an oxygen-free environment through a process called anaerobic digestion and another works best in an oxygen-rich environment through a process called aerobic fermentation.

Either conversion process is a form of nutrient recycling.

Depending on the raw material used, conversion to usable, benign plant food using the aerobic fermentation method takes place within two to three weeks versus three months to a year for composting.

The aerobic bioreactor can simply be a septic tank filled with water and equipped with an agitator. An oxygen concentrator connected to the tank provides a regular supply of oxygen to the beneficial microorganisms inside. Raw material like poultry or dairy manure or crop waste is fed into the tank, creating a slurry. Intense mixing and added oxygen encourage biological conversion over time. There is no odor produced during the process. After about three weeks, the conversion is mostly complete and the benign, highly concentrated, nutrient-rich liquid is removed from the bioreactor. Filtration separates the solids from the liquids. The solids are returned to the bioreactor for further treatment, while the liquid stream is ready to use as organic fertilizer.

In hydroponics, bioreactors are typically used to create a balanced ecosystem that provides plants with the nutrients they need to grow, while also removing waste products that can harm plant growth. The use of bioreactors in hydroponics has several important implications that allow for scale and a certified USDA organic seal.

One potential exploration of microbial bioreactors being placed in line with CEA hydroponic systems is the potential for nutrient cycling and zero-waste initiatives. Most CEA greenhouses are at the forefront of technology and utilize organic nutrients to supply their system. By adopting a closed loop with the implementation of a bioreactor that generates nutrients from waste it could create an affordable and sustainable best practice that is not accomplished in the industry - managing, unsellable, perishable produce and turning it into bioreactor food.

This could strengthen the brand of the CEA that utilizes this technology by demonstrating traceability of the inputs and communicating how the produce is sustainability grown and waste is used on site.

By improving nutrient management and reducing environmental impact, bioreactors can also have implications for plant quality and flavor. Studies have shown that plants grown in hydroponic systems with bioreactors can have higher levels of antioxidants and other beneficial compounds, as well as better flavor and aroma.

While bioreactors have many potential benefits for hydroponics, there are also some challenges associated with their use. One of the main challenges is ensuring that the bioreactor is properly balanced and inoculated with the correct bacteria from the start, is properly oxygenated with O2, and has a diverse population of microorganisms and nutrients for the system. If the bioreactor is not properly balanced, it can lead to nutrient imbalances or other issues that can negatively impact plant growth and lead to economic losses for the system.

By improving nutrient management, reducing environmental impact, and promoting plant health and quality, bioreactors have the potential to transform the way we grow plants in hydroponic systems. As research in this area continues to evolve, it will be exciting to see how bioreactors can be further optimized to improve the efficiency and sustainability of hydroponic farming.

This is all about turning one man's waste into another man's treasure.

Thanks for reading!