North America regional grit gradation data now available
Following comprehensive testing, grit gradation data is now available at a regional level to help North American wastewater engineers, owners and operators to design and optimise grit removal systems for wastewater treatment plants.
The data sets, which have been compiled from over 120 tests conducted across the United States and Canada, contain average physical size data as well as settling velocity data, making them the most comprehensive resources available on grit and its behaviour.
The best way to analyse grit is by settling velocity
Virtually all conventional grit removal processes rely on gravity sedimentation to achieve the separation of grit from wastewater, and most conventional grit removal processes are designed based on the assumption that grit is spherical and has a specific gravity of 2.65. Not all grit maintains a specific gravity of 2.65, however, and other factors - such as particle shape, and encapsulation by fats, oils and grease (FOG) - significantly impact its settling velocity. Therefore, the best means to analyse grit is to determine the settling velocity for given particle size ranges.
Settling velocity data can be correlated to the measured settling velocity of a clean sand sphere. The settling velocity is expressed as the Sand Equivalent Size (SES), which is the sand particle size having the same settling velocity as the more buoyant grit particle. The correlated particle size or SES can then be used for accurate design of an effective grit removal process.
When true settling velocity is considered in the design, real-world removal efficiency of grit particles can be estimated more realistically. These data sets will help US and Canadian wastewater professionals to achieve this objective.
Get the data
Regional data sets and selected state- and province-level data sets are available on the Advanced Grit Management website.
Regional data sets
State and province data sets