Aerobic Digestion

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Nitrification-Denitrification Basins for Waste Water from A Poultry Slaughter House, Verona

Nitrification-denitrification basins for wastewater at a poultry slaughterhouse in Verona, Italy.

Aerobic wastewater treatments break down organic matter through the presence of oxygen.

Aerobic digestion is a biological wastewater treatment. Once sediments and substances such as oil are removed from wastewater in the primary treatment stage, aerobic treatments are used to break down organic matter through the use of oxygen.

Aerobic biological processes use natural microbial colonies and molecular oxygen to decompose organic substances in the wastewater. The microbes feed on undesired biological substances in the water, creating aggregates or “flocks” of organic substances and microorganisms that settle to the bottom of the container. This sludge is stable and usually can be disposed of easily.

Aerobic treatment is typically part of a multistage water treatment process. The technology is not confined to use as an intermediate stage, but can also be used for finishing water and to augment other types of treatments.

Custom Aerobic Wastewater Treatment Solutions for Industrial and Municipal Clients

RWL Water is an expert in the implementation of aerobic treatment systems that treat wastes from a range of industries, including industrial processors such as paper and pulp mills, as well as food processing operations such as slaughterhouses and food-processing plants. Aerobic processes include activated sludge, oxidation ditches, trickling filter, lagoon-based treatments, and aerobic digestion:

  • The activated sludge process is a proven biological wastewater treatment widely used in secondary wastewater treatment, both domestic and industrial. It is particularly well suited to treating waste streams high in organic or biodegradable content. It is most often used to treat municipal sewage, wastewater generated by pulp and paper mills, food-related industries such as meat processing, and any industry producing waste streams containing carbon molecules. The technology can be used in plants of all sizes. RWL Water packaged wastewater treatment plants commonly use the extended aeration activated sludge treatment process.
  • An oxidation ditch is a basin through which wastewater flows. This secondary treatment process is used for both the nitrification and denitrification of wastewater. While circulating effluent after primary treatment, the wastewater is mixed with other sludge. Aeration adds oxygen into the process and encourages microbial growth in the wastewater. Once clarified, additional treatments may be needed, depending on the end use of the treated water.
  • Trickling filters are a type of aerobic treatment that substitutes for an aeration basin in a packaged wastewater treatment plant or a larger aeration plant. These mixed media filters are commonly used to remove compounds such as ammonia from the water after primary treatment. They also can be used as an intermediary stage in a cycle between anaerobic digestion and clarification to remove substances including biodegradable organic compounds.
  • A lagoon is a wastewater holding compartment in which aeration in performed. Although these basins can be used for solids settling, the addition of aeration equipment accelerates the biological processes. The wastewater, as it enters these large basins or holding ponds, courses down an inlet at which an aerator is positioned to force more air into the wastewater. This process produces high oxygen transfer and mixing below the surface.

Equipment used in aerobic treatment may include diffused aeration systems or mechanical surface aerators, such as RWL Water’s Tornado surface aerators. Aerators help maximize oxygen transfer and minimize odors as the wastewater is treated.

Aerobic Digestion Case Studies

Aerobic Treatment for Paper Mill

Aerobic Treatment for Paper Mill

Aeration is used as the final clarification step of wastewater treatment at the Cartiere di Tivoli paper mill in Rome.

Aerobic treatment was used as part of a comprehensive wastewater treatment package RWL Water designed for the Cartiere di Tivoli paper mill in Rome. The plant, built in 2009, produces 100 cubic meters (26,000 gallons) of wastewater an hour in the production of 300 tons of paper a day. It uses anaerobic pretreatment followed by a nitrification/denitrification process before aeration is used for finishing.

The aerobic finishing treatment process occurs in an oxidation basin. The water is aerated using bubble cannons (a fine bubble aeration system is inadvisable for this particular application because of the wastewater’s hardness and high alkalinity). The water then undergoes a final clarification process.

Aerobic Treatment for Slaughterhouse

Aerobic Treatment for Slaughterhouse

RWL Water included aerobic stages in the wastewater treatment package it designed for the AIA Villaganzerla chicken slaughterhouse in Vicenza, Italy.

Aerobic treatment is part of a comprehensive wastewater treatment package that RWL Water designed for AIA Villaganzerla in Vicenza, Italy. The plant, which was built in two phases in 2007 and 2010, slaughters 90,000 chickens a day and produces 5,000 tons a month of slaughter rendering. A total of 2,000 cubic meters (528,000 gallons) of wastewater is generated every day.

The slaughter rendering is treated using many stages, including anaerobic digestion, which  is followed by the aerobic treatment of ammonia, organic nitrogen, and residual chemical oxygen demand. Additional aerobic treatment occurs in the form of air flotation.

Decades of Aerobic Digestion Expertise

All RWL Water aerobic treatment systems are engineered to match your unique water or wastewater treatment challenges. Our equipment is ruggedly built, specifically designed to provide users with extended, trouble-free operation.

Let our technical experts assist you in the proper sizing, layout, and operation of your aerobic system.

Contact RWL Water for more information about our aerobic treatment solutions, or to request a quote.