Sorption gullies

Purpose

Wastewater treatment of minor pollutant sources containing liquid petroleum products as washing water of workshops, of small parking lots and the like.

Process
 

Water containing liquid petroleum products flows through a gulley grating in a sedimentation and separation zone of the first stage where coarse matters entrained (sand, clinker) are retained. Liquid petroleum substances and fine settleable substances are entrapped in the second sedimentation stage before a sorption unit where they flow vertically through. Sorption unit is filled with FIBROIL – selective fibre material. After passing through the sorption unit effluent water flows under a scumboard to sewerage. Sorption system is designed for a hydraulic load up to 0,8 l/sec. if a load is higher excess water can pass beyond the sorption system over a spillway crest of relief and under a scumboard to sewerage.

Description of Design

Sewer gully is a watertight plastic tank welded of 15 mm thick polypropylene panels. It is designed with respect to sewerage process conditions. For this reason an attention is paid for protection against intensive silting with solid flowing materials and suspended substances, i.e. the sorption inflow is out of a sludge-storage space of settling section. FIBROIL, fibre sorption element, is installed between grids in an optimally thick layer corresponding to its mechanical properties.

Design complies with CSN 756 551 Standard.
 

Embedding

Sorption gully is placed at the sewerage level to a prepared reinforced concrete slab. After connecting to sewerage the gully is covered around by concrete and a beam for grid and cover supporting frame is placed through which the settling zone and sorption filter are accessible.

Operation and Attendance

Attendance follows the service regulations. It concerns the inspection of settled sludge in both sedimentation stages, to take out entrapped petroleum products and to inspect permeability of sorption element. Zone under the sorption is accessible when taking a box with sorption material out. Sludge from settling section can be pumped out with a sludge removal truck. Sorption unit can be replaced.