Harsh environment structured packing

Overview
Trickling filters remain a proven wastewater treatment solution: simple to operate, reliable and energy‑efficient. Modern structured plastic fills allow compliance with current discharge limits while offering short payback times.

Description
Structured plastic fills (corrugated polypropylene sheets welded together) are used today to create an attached‑growth (biofilm) process adapted to multiple applications:

• Roughing for high influent concentrations
• Carbon removal (BOD reduction)
• Nitrification down to very low ammonia concentrations

Process engineering
A trickling filter is a fixed‑growth biomass system in which wastewater is distributed over a media supporting a biofilm. Distribution is performed from the top by rotating distributor arms (hydraulically or electrically driven). Aeration is achieved via vents at the bottom that allow free air flow. The media are supported on a substructure, typically parallel beams on concrete supports.

Performance and application types

• High‑performance trickling filters designed to reduce BOD by approximately 50%–70%; vertical structured fills expedite excess sludge removal when biomass growth is strong.
• Secondary treatment trickling filters to lower BOD and ammonia to levels suitable for discharge; some configurations can operate by gravity without additional energy input.
• Tertiary nitrification trickling filters to upgrade existing plants for ammonia removal; cross‑fluted structured fills provide high retention time and large specific surface, improving nitrification.

Upgrade of existing filters
Replacing mineral or random media with ENDEVION structured polypropylene fills is a cost‑effective way to increase capacity and performance. Structured fills support active biofilm, ensure oxygen and nutrient transfer, maintain channel free passage to avoid clogging and facilitate sludge removal, while reducing aeration energy requirements.

Municipal and industrial applications

• Municipal plants: fills can be configured to meet stringent discharge limits and to provide full secondary treatment or to augment existing plants with limited disruption.
• Industrial sector: suitable for wastewater with higher salinity or temperature, variable organic loads and pH; trickling filters produce limited excess sludge, have a small footprint and strong tolerance to inhibitory compounds.

Technical characteristics / specifications

• Fill material: corrugated polypropylene sheets, welded (not glued) for improved environmental compatibility
• Main applications: roughing (high influent concentration), carbon removal, nitrification to very low concentrations
• BOD reduction capability: typically 50%–70% for high‑performance fills
• Media arrangements: vertical structured fills; cross‑fluted options for increased retention time and specific surface
• Distribution: rotating distributor arms (hydraulic or electric) with defined hydraulic parameters for arms and nozzles
• Oxygen supply: vents at filter bottom allowing free airflow
• Substructure: media placed on parallel beams supported by concrete feet
• Operation modes: gravity operation possible for some secondary filters; low energy demand and high operational reliability
• Upgrade option: replacement of mineral/random media with ENDEVION structured polypropylene fills to increase capacity, reduce clogging and facilitate sludge removal
• Benefits: limited excess sludge production, high treatment stability, small footprint, easy maintenance, energy savings for aeration