In a previous article, we discussed the benefits of using digestate for dewatered fertiliser, though digestate by-products can be used in many other applications depending on their composition. Alongside this, there are also numerous benefits to implementing effective on-site wastewater treatment solutions that can help separate digestate from clean water and save companies money through wastewater recycling.
What is digestate?
Digestate is the residual, nutrient-rich material that is left over following anaerobic digestion – a process which relies on bacteria to break down organic matter without the use of oxygen. This process is often used in the agricultural, food, and beverage industries as a way to dispose of otherwise unusable or discarded elements such as animal waste, stomach contents, fats, dairy products, and more.
Is digestate a solid or a liquid?
It can be a combination of both – digestate comes in three distinct states: whole, liquor, and fibre. Whole refers to digestate in its unfiltered form which usually has a consistency similar to that of slurry or sludge and tends to contain 5% or less dry matter. Liquor is liquid digestate that has had most of the solid materials removed but some may still be dissolved in the wastewater. And lastly, fibre is the solid, dry material separated from whole digestate.
Common digestate by-product uses
Crop fertiliser
Due to the richness of organic matter in digestate, the processed, dewatered digestate is ideal for use as fertiliser to promote healthy crop growth. It is an ideal alternative to synthetic fertiliser as it contains all the required nutrients without the need for artificial production and this makes it a cheaper form of fertiliser as well as enabling a more sustainable recycling process across many industries.
Soil amendments
Alongside being an effective crop fertiliser, digestate (specifically fibre digestate) can be used as a soil amendment or soil conditioner to improve the consistency of the soil structure, its ability to retain water, ease of plant root penetration, and more. Soil amendment is ideal for use during the autumn months ahead of winter; or in spring to promote healthy growth.
Animal feed supplements
As digestate is rich in nitrogen, this makes it ideal for use in animal feed supplements. Nitrogen is essential for the production of skin tissue, milk, wool, and eggs, which is why supplements are used alongside a grass diet for many farm animals.
Biogas fuels
One of the main by-products of anaerobic digestion is biogas – digestate treatment systems such as the LAT Unit can capture biogas for further processing so it can be used as vehicle fuel or even for heating or cooking. Biogas is usually composed of around 50-65% methane gas and around 35-50% carbon dioxide and it’s become a particularly popular renewable fuel in China with over 50 million households being powered by biogas.
Alongside this, when biogas is upgraded to a higher percentage of methane and compressed, it can be used in vehicles as fuel. Biogas-powered vehicles can help reduce greenhouse gas emissions by as much as 80% compared to traditional fossil fuels.
Electricity generation
Further to being a great source of fuel for powering homes and vehicles, biogas can additionally be used in combustion engines to power electric generators which produce electricity. On average, one cubic metre of biogas can generate 2 kWh of electricity, which is the equivalent of keeping a 100W bulb lit for 20 hours.
Benefits of digestate recycling
Alongside the benefits of using digestate by-products, recycling digestate also has wider environmental benefits including:
Improved waste management
Effectively treating digestate and extracting useful by-products can reduce reliance on synthetic fertilisers and mitigate the environmental impact of poor organic waste management. If released untreated into the environment, digestate can pollute ecosystems and have adverse effects on all plants and creatures due to the range of bacteria that may be present, resulting in a depletion of natural resources over time. Untreated digestate can contain harmful pathogens, heavy metals, and other contaminants – making the treatment process crucial.
Alongside this, if organic waste is left to decompose in landfill, methane and other harmful gases will not be collected and will instead be released into the atmosphere – contributing further to greenhouse gas emissions.
Reduced greenhouse gas emissions
As we mentioned above, organic waste will naturally decompose to produce greenhouse gases, however, when effective treatment solutions are employed, these gases can be collected and neutralised or recycled so they are not released into the atmosphere. Additionally, treating digestate on-site reduces the need for transport which will further reduce CO2 emissions as well as minimising organisational spend.
Better water quality and availability
Further to the positive effects on the atmosphere, collecting and adequately treating digestate can reduce odours and prevent freshwater contamination, which additionally prevents the spread of waterborne diseases. By treating digestate and recovering clean water with the LAT Unit, this also allows for better on-site water recycling and minimises the reliance on new freshwater resources, ensuring its availability for other uses such as household or recreational uses.
Improved agricultural productivity
One of the primary benefits of digestate treatment is that it increases nutrient availability – during the anaerobic digestion process, organic matter is broken down into simpler compounds, which results in the release of nutrients including nitrogen, phosphorus, and potassium. When digestate is applied to the soil as a fertiliser or conditioner, it provides a slow-release source of nutrients that can sustain plant growth over an extended period.
Contact The LAT Water Team
Find out more about our wastewater management and digestate treatment solutions by contacting our team on +44 (0)1635 635900 or by emailing info@latwater.com. Download our corporate brochure for more details.
