Performance of an On-Site Wastewater Treatment System Using Reactive Filter Media and a Sequencing Batch Constructed Wetland

• Many on-site wastewater treatment systems, such as soil treatment systems, are not sustainable in terms of purification efficiency, nutrient recycling potential, and economics. In this case study, a sequencing batch constructed wetland (SBCW) was designed and added after a package treatment plant (PTP) using reactive filter media for phosphorus (P) removal and recycling. The treatment performance of the entire system in the start-up phase and its possible applicability in rural areas were investigated. Raw and treated effluents were sampled during a period of 25 weeks and analyzed for nitrogen, phosphorus, BOD7, and bacteria. Field measurements were made of wastewater flow, electrical conductivity, oxygen, and temperature. The entire system removed total-P and total inorganic nitrogen (TIN) by 83% and 22%, respectively. High salt concentration and very low wastewater temperature were possible reasons for these unexpectedly low P and TIN removal efficiencies. In contrast, removal rates of bacteria (Escherichia coli, enterococci) and organic matter (as BOD) were high, due to filtration in the alkaline medium Polonite((R)) (Ecofiltration Nordic AB, Stockholm, Sweden) and the fine sand used as SBCW substrate. High pH in effluent from the PTP was efficiently reduced to below pH 9 in the SBCW, meeting recommendations by environmental authorities in Sweden. We concluded that treating cold on-site wastewater can impair treatment performance and that technical measures are needed to improve SBCW performance.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Naturresursteknik -- Annan naturresursteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Environmental Engineering -- Other Environmental Engineering (hsv//eng)

Nyckelord

add-on unit

biofiltration

nitrogen

package treatment plant

phosphorus

Polonite

sand

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)