Headworks – Primary Treatment

Primary Treatment – Wastewater Screens

The treatment of municipal sewage at any wastewater treatment plant all starts at the same place – at the headworks screens. Initial wastewater screening is a crucial first step in primary treatment to ensure that the complex series of physical, chemical and biological processes within the municipal wastewater treatment plant work effectively and efficiently.

In recent years municipal sewage treatment processes have become increasingly more sophisticated. Regulations around effluent discharge, as well as solid waste disposal, have become more stringent. This has driven advances in primary treatment technologies in both headworks screening as well as the processing of the inorganic waste screened out by the headworks screens.

Coarse Screening and Grinding

It is critical to have some level of primary treatment protection at the headworks of a treatment plant.  If the plant is fed from a combined sewer system there is the possibility tires, tree branches, lumber, or other heavy objects can damage downstream treatment equipment. Automatic bar screens, which screen out heavier debris utilizing closely spaced vertical bars, are one potential level of primary treatment protection. Both the JWC’s Mechanical Bar Screen Monster and Chain and Rake Monster wastewater screens can provide coarse screening protection at the headworks.

An alternative to coarse screening is utilizing a JWC Channel Monster – a two shafted grinder to shred larger debris. The inorganics can then be removed by a fine screen without the risk of damaging other equipment. The Channel Monster can offer lower capital and operational cost to municipal wastewater treatment plants when dealing with large solids at the headworks.

Fine Headworks Screens

Fine Screening is now an essential part of a modern treatment plant’s headworks.  Primary treatment fine screens are bi-directional headworks screens utilizing perforated plates or drums. JWC’s Bandscreen Monster, Finescreen Monster or Drumscreen Monster® are fine screens that typically have openings from 1 to 6mm. These products can remove smaller pieces of trash such as wipes, plastics, latex, and cotton swabs that can easily slip through coarse screens.

For smaller plants with lower flows, JWC’s Auger Monster is an all-in-one headworks fine screening system. This in-channel system will grind up tough debris, screen the flow down to 6 mm and dewater the solids as they are removed from the channel.

Screenings Washing and Compacting

Disposal of the solids screened out at the headworks is another challenge for treatment plant operators. A heavy-duty washer compactor can receive solids from wastewater screens, separate out the soft organics, and then compact and dewater the inorganic trash. JWC’s Screenings Washer Monster is the ideal solution for this. Screenings are dropped into a powerful Muffin Monster grinder which breaks open the trash and flushes the fecal and soft organic materials back into the plant flow. The remaining solids are compacted and dewatered resulting in up to 95% less screenings by volume.