A Biofiltration System

Biofiltration is the filtration of contaminated water using organic material to capture and biologically degrade contaminants. A biofilter comprises inorganic or organic filtering media such as rock, slag, sand, glass beads, peat or wood chips on which a biofilm develops when wastewater flows over the filtering media during use. The biofilm serves as a bioorganic contact reactor and removes organic and inorganic contaminants from the contaminated water. With continued use, the biofilm continuously thickens leading to an accumulation of matter in the filtering media that eventually may clog the filter, thereby reducing the flow of wastewater through the filter. The biofilm may be periodically cleaned from the filtering media using oxidising chemicals or may be washed off using a burst of water or air. This can be a time-consuming process requiring additional labour and creating filter downtime.

A biofiltration system using a biofilm contact reactor has been developed to remove organic contaminants from wastewater. The biofiltration consists of a tower with a packed bed of porous substrate material, designed efficiently to distribute wastewater over the substrate, with the simultaneous draft of air in the opposite direction, ensuring effective aeration of the system without additional energy required to power aeration. 

Contaminated water enters the tower through the water inlet and a biofilm of a mixed population of microorganisms is on the surface of the packed bed material. The biofilm covers a large surface area and, as it thickens, it serves as a biological scrubber removing organic matter, and trapping solids, removing from wastewater. When the biofilm becomes too thick and heavy to remain attached within the system, it is shed, providing a novel means to remove waste biofilm biomass from the system. At the same time, a new biofilm develops without interrupting the operation of the system.The resulting biological sludge and solid waste matter are constantly removed by making use of a highly effective in-line separation method to produce a small volume of concentrated waste stream and a separate filtered water stream. 

The technology has the following advantages over the conventional filtration system:

• Biological contaminants and solid materials are continuously separated out of the water without the need to disrupt the operation to clean the packed bed.
• The system required no additional settling tank.
• The system does not use filters that need to be cleaned or can become clogged with use.
• Only a small amount of waste is produced from the filtration process leading to a lower environmental impact.
• The design of the filter allows for a greater aeration rate than a conventional filter, allowing for a quicker breakdown of organic matter.
• The system has a smaller footprint than conventional filters.
• Almost (or none) pre-fabricated components are required.
• Small capital outlay to implement, especially if an existing water-cooling tower is on site.
• Continuous biofiltration produces separate streams of waste and filtered water.
• The system separates solid and organic waste material from water in one tank.
• No filters are used in the technology which means less clogging than traditional filtration systems.

The technology can be applied in:

• Wineries producing cellar effluent.
• Production facilities that produce water with inorganic waste components.
• Wastewater management companies