Treatment Using Porous Media Biofilters
Porous media biofilters are designed to exploit attached growth biological processes to achieve advanced secondary treatment. Primary treated wastewater is intermittently dosed onto the surface of the biofilter and migrates by unsaturated flow through a d
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8-1. Scope Porous media biofilters are designed to exploit attached growth biological processes to achieve advanced secondary treatment. Primary treated wastewater is intermittently dosed onto the surface of the biofilter and migrates by unsaturated flow through a depth of media upon which biofilms grow. This chapter describes the principles and processes associated with porous media biofilters and covers the design and implementation of intermittent and recirculating sand filters and packaged media biofilters. The design of pressurized delivery and distribution networks is also covered in detail in this chapter.
8-2. Key Concepts ■
Porous media biofilters (PMBs) can be established using different types of media in different configurations. • At a basic level they all include intermittent application of primary treated wastewater over the surface of a biofilter media, which is typically housed in some type of container. During unsaturated flow through the biofilter aerobic conditions are maintained (typically by passive aeration) so that advanced secondary treatment can occur, principally by attached growth biological processes. • Intermittent application and uniform distribution of the wastewater applied to the biofilter surface is normally accomplished using networks of pressurized piping and perforated distribution laterals. Wastewater effluent pumps or dosing siphons can be used for intermittent application and network pressurization.
© Springer International Publishing AG 2017 R.L. Siegrist, Decentralized Water Reclamation Engineering, DOI 10.1007/978-3-319-40472-1_8
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Treatment Using Porous Media Biofilters
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PMBs are similar to trickling filters in that they both rely on attached growth biological processes, but PMBs are different in that they typically have finer media with less media bed depth and lower hydraulic and organic loading rates. This chapter describes the process principles and design of several types of PMBs that are commonly used in decentralized systems.
Single pass sand filters (SPSFs) have a long history of use in treatment of wastewaters generated by houses, residential developments, commercial and institutional establishments, and small towns. • The media used in most SPSF is screened and washed medium to coarse sand. Critical media suitability parameters are the effective size (ES), uniformity coefficient (UC), and %fines content. Typical specifications are: ES ¼ 0.25–1.0 mm, UC 4, and %fines (D
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