Role of Anaerobic Digestion in Food Waste Management

Food waste is one of the single largest constituent of municipal solid waste stream. In a typical landfill, food waste is one of the largest incoming waste streams and responsible for the generation of high amounts of methane. Diversion of food waste from landfills can provide significant contribution towards climate change mitigation, apart from generating revenues and creating employment opportunities.

 

Of the different types of organic wastes available, food waste holds the highest potential in terms of economic exploitation as it contains high amount of carbon and can be efficiently converted into biogas and organic fertilizer. Food waste can either be utilized as a single substrate in a biogas plant, or can be co-digested with organic wastes like cow manure, poultry litter, sewage, crop residues, abattoir wastes etc or can be disposed in dedicated food waste disposers (FWDs). Rising energy prices and increasing environmental concerns makes it more important to harness clean energy from food wastes.

Anaerobic Digestion of Food Wastes

Anaerobic Digestion of Food Wastes

Anaerobic digestion is the most important method for the treatment of food waste because of its techno-economic viability and environmental sustainability. The use of anaerobic digestion technology generates biogas and preserves the nutrients which are recycled back to the agricultural land in the form of slurry or solid fertilizer. The relevance of biogas technology lies in the fact that it makes the best possible utilization of food wastes as a renewable source of clean energy.

A biogas plant is a decentralized energy system, which can lead to self-sufficiency in heat and power needs, and at the same time reduces environmental pollution. Thus, the benefits of anaerobic digestion of food waste includes climate change mitigation, economic benefits and landfill diversion opportunities.

Anaerobic digestion has been successfully used in several European and Asian countries to stabilize food wastes, and to provide beneficial end-products. Sweden, Austria, Denmark, Germany and England have led the way in developing new advanced biogas technologies and setting up new projects for conversion of food waste into energy.

food waste treatment

Codigestion at Wastewater Treatment Facilities

Anaerobic digestion of sewage sludge is wastewater treatment facilities is a common practice worldwide. Food waste can be codigested with sewage sludge if there is excess capacity in the anaerobic digesters. An excess capacity at a wastewater treatment facility can occur when urban development is overestimated or when large industries leave the area.

anaerobic_digestion_plant

By incorporating food waste, wastewater treatment facilities can have significant cost savings due to tipping fee for accepting the food waste and increasing energy production. Wastewater treatment plants are usually located in urban areas which make it cost-effective to transport food waste to the facility. This trend is catching up fast and such plants are already in operation in several Western countries.

The main wastewater treatment plant in East Bay Municipal Utility District (EBMUD), Oakland (California) was the first sewage treatment facility in the USA to convert post-consumer food scraps to energy via anaerobic digestion. EBMUD’s wastewater treatment plant has an excess capacity because canneries that previously resided in the Bay Area relocated resulting in the facility receiving less wastewater than estimated when it was constructed. Waste haulers collect post-consumer food waste from local restaurants and markets and take it to EBMUD where the captured methane is used as a renewable source of energy to power the treatment plant. After the digestion process, the leftover material is be composted and used as a natural fertilizer.

The first food waste anaerobic digestion plant in Britain to be built at a sewage treatment plant is the city of Bristol. The plant, located at a Wessex Water sewage works in Avonmouth, process 40,000 tonnes of food waste a year from homes, supermarkets and business across the southwest and generate enough energy to power around 3,000 homes.

Aside from the coprocessing of food waste in wastewater treatment facilities, they can also incorporate greener and more cost-effective agents aiding the wastewater treatment process. For centuries, wastewater companies have utilized caustic soda or sodium hydroxide, a strong alkaline substance, to ionize and increase the pH level of water. This substance is also useful for eliminating heavy metals in water.

Despite the effectiveness of sodium hydroxide in wastewater treatment, corrosion of pipelines is a huge issue in many facilities, as well as the release of copper and lead when water flows into residential plumbing fixtures. However, when the pH of water is increased further, copper and lead contamination can be temporarily resolved, but at the expense of insoluble calcium carbonate build-up along pipe walls.

To present a better solution to this dilemma, wastewater plants can use a sodium hydroxide substitute like magnesium hydroxide which can serve as a greener, safer, and more cost-effective alternative. Compared to caustic soda, magnesium hydroxide offers the following advantages:

  • 40% reduction in chemical usage
  • Safer handling for wastewater facility operators
  • Less hazardous and more nutritive to microorganisms being maintained
  • Reduced sludge volume, thus lowering sludge hauling fees
  • Doesn’t irritate and burn the skin when in contact

A magnesium hydroxide alternative can perform the same advantages as the traditional caustic soda, but with less damages to people and the environment. If you’re looking into using new substitutes like sodium hydroxide in your facility, make sure to consult certified experts like a plant operator, chemical engineer, mechanical engineer, sanitary engineer, and the like.

How Can Launder Covers Help Water Environments

The conservation of water, its proper flow, and assured safety for home or industrial use can be achieved by reusing water through renewable energy. However, algae control is challenging even for modern wastewater treatment plants. One of the best ways of resolving this problem is by installing launder covers.

Aside from this concern, water ecosystems also face other issues, the most notable being water and wastewater treatment facilities. So how can launder covers be of any help in such a scenario?

The discussion that follows will serve as a useful reference point when choosing the right launder cover for your water and wastewater treatment facility. Let’s get up to speed on how launder covers can help water environments.

Prevent Algae Growth

Algae growth has a proven tendency of developing in water and wastewater treatment facilities. It causes changes in the hydraulic dynamics of clarifiers, which leads to obstruction of design features found in weir configurations. Once launder covers are installed, they provide an attractive and extremely low maintenance structure to help eliminate algae growth problems.

Also, larger algae can dislodge and move around in plants that utilize ultraviolet disinfection technology. If the floating algae ends up covering UV bulbs, this may cause bulb failure and render UV bulbs ineffective, which are unfortunately very expensive to replace.

That’s why the installation of reliable launder covers, like IEC Covers, is recommended to help prevent algae growth in water and wastewater treatment plants. This would save money on repairs and UV bulb replacement at the same time.

Control Gas And Odor Emissions

Launder covers are useful in providing a continuous protective environment above the effluent stream. They can contain odor and gas to prevent environmental pollution and protect the health of workers in the area.

A reliable and corrosion-free launder cover system prevents direct sunlight from reaching the elevated growth areas of the weir and clarifier launder. Since launder covers serve as odor control hoods, they trap noxious gases that are generated during wastewater treatment processes.

Provide Essential Value To Water Environments

Custom designed launder covers can be placed in rectangular and round tanks, providing essential value for different water and wastewater operations. This page will teach you everything about wastewater treatment.

Here are the advantages of installing launder covers in water environments:

  • Continuous inhibition of algae growth
  • Lightweight and cost-effective solution for water problems
  • Operable access for safety inspections and preventive maintenance

Maintain Weir Structural Integrity And Function

Eliminating direct sunlight inhibits algae growth, which also enhances the flow consistency of weir and reduces the need for maintenance. Launder covers shield other openings where access is normally required, but for safety reasons they need to be covered when not being used.

You can request custom-designed launder covers according to your preferred requirements. Custom-designed launder covers can be used in both round and rectangular clarifiers, as well as channels, sludge thickeners, and other openings.

Acts As Debris Barrier

Plastic bags, leaves, dead tree branches, and other windblown debris often lands in water environments. Launder covers help prevent such waste materials from ending up in your water and wastewater plant.

Also, aside from preventing debris from entering the water stream, launder covers can also be helpful in containing localized odor emissions if present in the weir area (effluent trough). Choosing fiberglass launder covers helps seal water environments in order to control odor.

Protect Launder From Weather

Strong winds, storms, snow, or heavy rainfall may introduce debris to water environments. Installing launder covers helps protect them against debris and damage caused by natural disasters. Choosing high-quality launder covers will ensure that they can withstand harsh weather conditions while protecting water and wastewater treatment plants.

Here’s a quick guide for when you are choosing launder covers:

  • NSF/ANSI Certified: Choose launder covers that are NSF or ANSI 61 certified. Also, opt for launder covers made of AWWA F101 compliant materials. NSF/ANSI Standard 61 or NSF-61 refers to a national standard relating to water treatment, establishing strict requirements and controls for equipment coming in contact with potable water or other products supporting the potable water production.
  • Quality Make: Select launder covers with superior strength and corrosion resistance that use FRP components to ensure long and maintenance-free service life. Choose clarifier launder covers that utilize fiberglass and stainless steel hardware, specifically made for municipal or industrial wastewater treatment purposes. These launder covers are easy to use, ensuring smooth operation and meeting the required NPDES effluent levels of Total Suspended Solids or TSS.
  • ISO Certified: Choose an ISO 9001 certified launder cover for manufacturing facilities.

Conclusion

Launder covers provide great protection against debris, harsh weather conditions, and direct sunlight. They further help protect weir structures, prevent algae growth, and are handy in avoiding the potential damage that algae can do to UV bulbs in treatment facilities using UV disinfection technology.

Choosing high-quality launder covers would mean having long-term peace of mind that your water quality is preserved and wastewater treatment operations can function smoothly.