Historically, wastewater has been regarded as a human health risk and environmental hazard, but a shift in current attitudes now values wastewater as a potential source of recyclable materials and energy. It plays an important role in recovering resources that are becoming increasingly scarce.
Wastewater contains tissue paper fibers and this material can be harvested and processed to create cellulose which can be used for a variety of useful things. An initiative in the Netherlands has created a system that can extract cellulose from sludge at its Geestmerambacht Wastewater Treatment Plant. It is considered to be the first full-scale implementation of sewage-to-cellulose recycling plant in the world producing high-quality cellulose which has practical applications in several industries. It’s one of six pilot programs hosted by SMART-Plant in the European Union which aims to create sustainable materials from circular wastewater management.
The Salsnes Filter system will separate fine cellulose fibers from toilet paper in the wastewater to produce a highly-concentrated sludge. It is then sent for post-processing inside the treatment plant. A compact sequence of equipment from the paper and food industries will treat the sludge to produce clean and marketable cellulose. By filtering sewage at the beginning of the treatment process, a significant amount of suspended solids is removed, thereby saving energy that is necessary for the biological processes downstream (aeration). In addition to these energy savings, there are other advantages such as lower biological sludge production, lower polymer consumption for dewatering, and less maintenance for removal of hairs and fibers. The energy savings can amount to 15-20% for the aeration and the savings on polyelectrolyte usage is as much as 20%.
The material that is recovered with the CellCap finescreens at the beginning of the purification are called cellulosic screenings. This material consists of 70 – 80% of cellulose which is the main component of toilet paper. Cellulose is an interesting by-product for reuse in many commercial products.
It is anticipated that cellulose harvesting will have added benefits to the WWTP’s downstream biological process. The results are expected to show energy savings and a reduced amount of secondary sludge produced. The amount of clean, usable cellulose that the plant creates is around 400 kg daily.
The extracted cellulose may be used to manufacture commercial products like bottles and recycled toilet paper. One creative use of the high-grade cellulose is for paving bicycle lanes. The Dutch Water Authorities invited Studio Nienke Hoogvliet to design a range of products from recovered cellulose. Studio Nienke Hoogvliet created a range of products including large tables, lighting fixtures, and decorative bowls. It serves to highlight how these recycled materials can be integrated into useful items for homes and offices. It aims to create a positive image of wastewater as a potential source of valuable materials.
If you are a municipality in Ontario and in need of a biosolids management solution, please feel free to contact us at 1 (877) 479-1388.