Can an Integrated Constructed Wetland in Norfolk Reduce Nutrient Concentrations and Promote In Situ Bird Species Richness?

Abstract

Integrated Constructed Wetlands (ICWs) are potentially effective tools in the effort to restore aquatic ecosystems, and also they incorporate multiple co-benefits. An ICW was constructed in Norfolk, UK, to address the degradation of a stream and lake receiving treated effluent from a small Sewage Treatment Works (STW). Results demonstrated that: (1) nutrient concentrations significantly reduced from the ICW influent to the effluent (percentage reductions: total phosphorus [TP]: 78%, orthophosphate: 80%, total oxidised nitrogen [TON]: 65%, nitrate: 65%, nitrite: 67%, ammoniacal nitrogen: 62%), and mean dissolved oxygen concentrations increased (influent mean: 6.4 ± 1.4 mg l −1 effluent mean: 17.8 ± 3.3 mg l −1 ), (2) there were non-significant reductions in nutrient concentrations in the receiving stream (percentage reductions: TP: 23%, orthophosphate: 23%, TON: 26%, nitrate: 26%), with the exception of ammoniacal nitrogen (127% increase) and nitrite (76%) after ICW commissioning, and (3) mean in situ avian species richness increased from 10 to 27 species. Thus, the ICW substantially reduced nutrient concentrations, and had in situ conservation benefits. It is recommended that appropriately designed ICWs should be implemented widely and statutory authorities should ensure: 1) best-practice maintenance and 2) final effluent monitoring at both the STW and at the ICW outflows.

Assessing the environmental and economic efficacy of two integrated constructed wetlands at mitigating eutrophication risk from sewage effluent

“…2; Table 1), whilst mean nitrate loading into the River Mun was reduced by 55.7% relative to the loading into the ICW from the WWTP (Table 2). These removal efficiencies are consistent with previous studies of constructed wetlands, which have typically reported nitrate reductions of 40‐60% (Vymazal, 2007; Almuktar et al ., 2018; van Biervliet et al ., 2020). Nitrate reduction is dominantly caused by bacterially driven aerobic nitrification of ammonia to nitrate, followed by anaerobic denitrification to nitrous oxide and nitrogen gas within the root zone, coupled with assimilation by plants and periphyton (Scholz and Lee, 2005; Xiong et al ., 2011; Vymazal, 2013).…”

“…This equated to a total cost per person served by the River Mun WWTP of £39, based on a population of 772 people. For comparison, Anglian Water estimated that installing chemical phosphorus stripping at the River Ingol WWTP, which has the potential to reduce phosphorus concentrations by ~90%, would incur a capital cost of £1 million with an additional operating cost of £0.5 million per annum (van Biervliet, 2015a). Given such high capital costs of installing ion exchange and chemical precipitation technologies at WWTPs to remove nitrogen and phosphorus (Sengupta et al, 2015), these ICWs provide a natural, cost-effective, alternative to conventional tertiary wastewater treatment.…”

Constructed Wetlands in Wastewater Treatment and Challenges of Emerging Resistant Genes Filtration and Reloading

“…Several forms of constructed wetlands have been introduced, including surface flow wetlands, subsurface flow wetlands, and hybrid systems that integrate surface and subsurface flow wetland types [6,19]. Constructed wetland systems can also be combined with conventional treatment technologies to provide higher treatment efficiency [8]. The choice of constructed wetland types depends on the existing environmental conditions and how appropriate they are for domestic wastewater, agricultural wastewater, coal mine drainage, and stormwater [6].…”

“…Artificially created wetlands have been successful in the treatment of petroleum refinery wastes, wastes from sugar factory, leachates from landfills and composts, wastes from aquaculture systems, wastes from pulp and paper mills, and wastes that emanate from slaughter houses, textile mills, and plants that process sea food. Under the management of these wastes, the constructed wetlands can serve as the sole treatment or may be part of an integrated wastewater treatment system [8].…”

Influence of Aquatic Plants and Flow Rate on Physico-chemical Characteristics of Sewage Effluent Treated through Constructed Wetland Technology

“…"Constructed wetland systems can also be used in conjunction with traditional treatment methods to improve treatment efficiency" [6]. "The selection of constructed wetland types depends on the prevailing environmental conditions and also the type of wastewater to be treated such as domestic wastewater, agricultural wastewater, coal mine drainage, and storm-water" [3].…”