Article:
Raw material recovery from wastewater

Wastewater treatment processes are integral not only for purifying water but also for extracting valuable raw materials from sewage, contributing to sustainability and resource conservation. Let’s delve deeper into the raw material recovery from wastewater.

Raw material recovery from wastewater – What can be recovered.

Proteins: Wastewater contains effluent characteristics conducive to protein recovery. Innovative processes involve single-cell protein production from food industry waste streams, showcasing the potential for protein-rich raw material extraction.
Biogas: Organic waste undergoes anaerobic digestion, yielding biogas as a renewable energy source. This not only aids in waste treatment but also aligns with the goal of harnessing clean energy.
PHA (Polyhydroxyalkanoates): Urban organic waste serves as a substrate for PHA production. Utilizing purple phototrophic bacteria, this process offers a sustainable alternative to traditional plastics, contributing to a circular economy.
Liquid CO2: Certain wastewater treatment methods capture and recover liquid carbon dioxide, providing an eco-friendly raw material with versatile applications.
Kaumera: Derived from wastewater, Kaumera is an innovative material with unique properties suitable for agricultural and industrial use, further emphasizing the diverse avenues of resource recovery.
Soil Amendments: Organic waste recycling in agriculture induces beneficial effects on plant-available water and soil properties, contributing to the circular use of waste materials.

Several of the products that can be recovered/made out of waste water require a stream of 100% organic waste. The waste stream coming from our GS-Food Waste Digester is this 100% organic stream, that can be quickly used for the production of several of these products. We therefor see a place of our machines in the circular economy and the importance of material recovery.

1. Protein Recovery for Sustainable Futures

The process of protein recovery from sewage water involves a series of steps that effectively purify and concentrate the protein content. Pretreatment removes large organic matter and solids, while primary treatment breaks down complex organic compounds using biological processes. Secondary treatment focuses on eliminating dissolved organic matter and nutrients like nitrogen and phosphorus.

The final step, protein recovery, employs various techniques to isolate and concentrate the protein fraction. Ultrafiltration membranes with selective pore sizes allow for the passage of water and small molecules while retaining proteins. Precipitation techniques, using chemicals like sulfuric acid or ethanol, induce protein aggregation, resulting in a concentrated protein fraction. Ion exchange resins selectively separate proteins based on their charged groups.

Harnessing the Diversity of Recovered Proteins

The specific types of proteins recovered depend on the source of the wastewater and the treatment processes employed. However, a general mix of proteins can be expected, including:

Myofibrillar proteins, derived from muscle tissue, are rich in essential amino acids, making them valuable for animal feed and food applications.
Serine proteases, found in blood, possess proteolytic activity, making them useful for industrial processes like leather tanning and cheese making.
Glutamic acid dehydrogenase, a key enzyme involved in amino acid metabolism, holds potential for industrial biotechnology and medical diagnostics.

A Spectrum of Applications for Recovered Proteins

The recovered proteins from sewage water can be put to work in a wide range of applications:

Animal Feed: Their high protein content makes them an excellent source of nutrients for livestock and aquaculture, contributing to a sustainable food production system.
Food Additives: Functionalized proteins can be incorporated into food products to enhance their texture, flavor, and nutritional value, diversifying the food industry.
Industrial Enzymes: Specific proteases and other enzymes can be extracted and purified for use in industrial processes like detergent production, leather tanning, and textile manufacturing.
Biomedical Applications: Certain proteins, like growth factors and antibodies, can be purified for medical applications, such as tissue engineering and drug development.

2. The Biogas Production Process

The process of biogas production from wastewater treatment plants involves several steps:

Pretreatment: The initial step removes large solids, suspended particles, and impurities from the wastewater. This is typically achieved through physical processes like screening, sedimentation, and flotation.
Digestion: The core of the biogas production process, anaerobic digestion, breaks down organic matter into simpler compounds, primarily methane and carbon dioxide. This reaction is facilitated by a consortium of microbes in anoxic conditions, where oxygen is absent.
Collection and Upgrading: The produced biogas is collected and purified to remove impurities like hydrogen sulfide, water vapor, and other non-combustible gases. This process, known as upgrading, involves absorption, pressure swing adsorption, or membrane separation techniques.

Applications of Biogas

The versatile biogas can be utilized in a wide range of applications:

Power Generation: Biogas can be directly combusted in engines to generate electricity. This energy can be used to power the wastewater treatment plant or exported to the grid.
Combined Heat and Power (CHP): CHP systems utilize the heat generated during biogas combustion to provide both electricity and heating, improving energy efficiency.
Compressed Natural Gas (CNG): Biogas can be upgraded to CNG, a clean-burning fuel suitable for vehicles, reducing dependence on fossil fuels and promoting a greener transportation sector.
Biofertilizers: By capturing nutrients from the wastewater, biogas production can produce nutrient-rich digestate, which can be used as a fertilizer for agricultural purposes.

3. PHA

Polyhydroxyalkanoates (PHAs) are a group of biodegradable polyesters produced by various bacteria as carbon and energy storage compounds. They are biocompatible, non-toxic, and have a wide range of potential applications, including bioplastics, pharmaceuticals, and cosmetics.

Recovery of PHAs from Wastewater

Wastewater treatment plants (WWTPs) provide a potential source for PHA recovery due to the presence of high concentrations of organic matter, which serve as the feedstock for microbial PHA production. The recovery process typically involves the following steps:

Pretreatment: The initial step removes large solids, suspended particles, and impurities from the wastewater using physical processes like screening, sedimentation, and flotation.
PHA Extraction: The remaining wastewater is subjected to a series of extraction methods to isolate PHAs from other organic matter. These methods may include solvent extraction, membrane separation, and microbial immobilization.
Purification: The extracted PHAs are further purified to remove impurities and concentrate the polymer fraction. This may involve precipitation, centrifugation, and filtration techniques.
Hydrolysis: In some cases, PHAs may need to be hydrolyzed to monomers, such as hydroxybutyrate (HB) and hydroxyvalerate (HV), for further processing or utilization. This step requires enzymes that can break down the polymer chains into their constituent monomers.

Recovery and Applications of PHAs

The recovered PHAs can be further processed into various forms, including pellets, powders, or films, for different applications. Some potential applications of PHAs include:

Bioplastics: PHAs can be used to produce biodegradable plastics, replacing conventional plastics derived from fossil fuels.
Pharmaceuticals: PHAs can be used as carriers for drugs, improving their stability and targeting properties.

Cosmetics: PHAs can be incorporated into skin care products due to their moisturizing and wound-healing properties.
Materials Science: PHAs can be blended with other polymers to create new materials with enhanced properties, such as biocompatible implants or flame-retardant coatings.

4. Recovery of Liquid CO2

The recovery of liquid carbon dioxide (CO2) from sewage water at wastewater treatment plants (WWTPs) is an emerging technology with the potential to address environmental concerns and create new value streams from wastewater. Sewage water contains dissolved CO2, which can be extracted and concentrated using various techniques. The recovered CO2 can then be used in various applications, including carbonation of beverages, enhanced oil recovery, and food preservation.

Process of Carbon Dioxide Recovery from Sewage Water

The process of recovering liquid CO2 from sewage water involves several steps:

Pretreatment: The initial step involves removing large solids, suspended particles, and impurities from the wastewater using physical processes like screening, sedimentation, and flotation.
CO2 Extraction: The remaining wastewater is subjected to a gas-liquid extraction process to selectively remove CO2. This may involve absorption, stripping, or membrane separation techniques.
CO2 Compression and Liquidization: The extracted CO2 is then compressed to high pressure and cooled to a low temperature, resulting in the formation of liquid CO2.

Applications of Recovered Liquid CO2

The recovered liquid CO2 can be used in a variety of applications:

Carbonation of Beverages: Liquid CO2 is a key ingredient in carbonated beverages, providing the fizzy sensation and enhancing flavor.
Food Preservation: Liquid CO2 is used as a refrigerant and preservative in food packaging, extending the shelf life of perishable products.

5. Making Kaumera

Kaumera, also known as Nereda gum, is a biopolymer produced by a consortium of bacteria found in anaerobic granular sludge (AGS), a type of sludge commonly generated in wastewater treatment plants (WWTPs). Kaumera is a versatile polysaccharide with potential applications in various industries, including cosmetics, pharmaceuticals, and food additives.

Process of Kaumera Recovery from Sewage Water

The process of recovering Kaumera from sewage water involves several steps:

AGS Pretreatment: The initial step involves thickening and dewatering the AGS to concentrate the bacterial community responsible for Kaumera production.
Kaumera Extraction: The concentrated AGS is subjected to a solvent extraction process to isolate Kaumera from other organic matter. This may involve using solvents like ethanol or acetone to solubilize Kaumera and precipitate it from the solution.
Purification: The extracted Kaumera is further purified to remove residual solvents and impurities using techniques like filtration, precipitation, and dialysis.
Characterisation and Functionalization: The purified Kaumera is characterized to determine its molecular structure and properties. It may also undergo functionalization processes, such as cross-linking or enzymatic modification, to enhance its desired properties for specific applications.

Applications of Recovered Kaumera

The recovered Kaumera can be utilized in various applications:

Cosmetics: Kaumera can be used as a thickening agent, gelling agent, and stabilizer in cosmetics and personal care products.
Pharmaceuticals: Kaumera can be used as a carrier for drugs, enhancing their stability and targeting properties.
Food Additives: Kaumera can be incorporated into food products as a thickener, gelling agent, and stabilizer, improving their texture and mouthfeel.
Environmental Applications: Kaumera can be used as a flocculant to enhance the settling of suspended solids in water treatment processes.

Biomaterials: Kaumera can be used to develop bio-based materials for various applications, such as tissue engineering scaffolds and drug delivery systems.

Recovering Kaumera from sewage water presents a valuable opportunity to enhance wastewater treatment processes, generate economic value, and contribute to a circular economy. By harnessing the potential of this biopolymer, WWTPs can play a pivotal role in transforming wastewater from a waste stream into a source of renewable resources and innovative products. As research and development in Kaumera recovery technologies continue, this practice is expected to gain momentum, paving the way for a more sustainable and resource-efficient future.

6. Soil Amendments

The process of recovering soil amendments from sewage water involves several steps:

Pretreatment: The initial step involves removing large solids, suspended particles, and impurities from the wastewater using physical processes like screening, sedimentation, and flotation.
Digestion: Anaerobic digestion, a biological process, breaks down organic matter into simpler compounds, such as methane and carbon dioxide, while producing a nutrient-rich sludge.
Drying and Granulation: The nutrient-rich sludge is dried to a manageable consistency and then granulated into a form suitable for agricultural applications.
Chemical Treatment: In some cases, additional chemical treatments may be applied to stabilize the soil amendments and enhance their effectiveness.

Types of Soil Amendments Recovered from Organic Waste

Sewage water, particularly from sources with high concentrations of food waste, can be a potential source for various soil amendments:

Biochar: Biochar is a carbon-rich material produced from the pyrolysis of organic matter, such as food waste. It improves soil structure, water retention, and nutrient cycling.
Hydrolyzed Digestate: Hydrolyzed digestate is the liquid fraction of anaerobically treated sewage sludge, enriched with nutrients like nitrogen, phosphorus, and potassium. It enhances soil fertility and promotes plant growth.
Solid Digestate: Solid digestate is the solid residue of anaerobically treated sewage sludge, containing a high concentration of organic matter and beneficial microorganisms. It improves soil structure, water retention, and microbial activity.
Compost: Compost is a mixture of organic waste that has been decomposed through aerobic microbial processes. It improves soil structure, fertility, and water retention, while also suppressing soil-borne diseases.

our three key pillars

In today’s environmentally conscious world, our three product lines stand out for their impactful contributions. Our food waste digesters efficiently convert organic waste into valuable resources, reducing CO2 and methane emissions and cutting waste disposal costs.

The enzymatic products we offer provide effective cleaning, pest control and soil enhancement solutions while minimizing chemical usage, promoting a safer and greener working environment.

Additionally, our green packaging alternatives eliminate the need for fossil-based plastics, reducing environmental harm and appealing to eco-conscious consumers.