Abstract
Simple and suitable treatment of swine slurry from small farms is paramount especially in sensitive areas. This paper evaluates the viability of an innovative nature-based technology hybrid system (a Vertical Flow Constructed Wetland followed by a Horizontal Flow Constructed Wetland both planted with reeds – Phragmites australis) to treat swine slurry for further land application or discharge in water bodies with reduced nitrogen impact. Physicochemical parameters, bacterial indicators, surface deposits and biomass inside the filters were monitored. The hybrid configuration offered a dual function for simultaneous solid-liquid separation and biological treatment. Removal of organic matter and suspended solids was very high (>80% for SS and >75% for COD and BOD5) while the overall nitrogen load removal was 65%, due to the combined nitrification/denitrification processes, thus effectively reducing swine slurry nitrogen content. The influence of temperature and design and operational parameters on the treatment efficiency and the hydraulic behavior were also studied. The vertical constructed wetland achieved good hydraulic performance with no clogging problems, despite high pollutant loads. Some of the pollutants were retained and mineralized in the surface deposit layer, increasing around 20 cm each year. This organic biosolid layer improved filtration efficiency. The high ammonia contents interfered with the growth of Phragmites australis, while the high concentration of suspended solids and organic matter determine the operation and design to be implemented.
Highlights
Agro-food activities, especially intensive livestock farming can produce high-strength wastewater with marked seasonal fluctuations in terms of quantity and quality
Swine slurry nutrients in excess of crop uptake can accumulate in soils, reaching an oversaturation of nitrates which afterward infiltrate and percolate
Influent wastewater presented the typical characteristics of swine slurry (Lee et al, 2014; Vidal et al, 2018), with high concentration of SS, organic matter, nitrogen and phosphorous
Summary
Agro-food activities, especially intensive livestock farming can produce high-strength wastewater with marked seasonal fluctuations in terms of quantity and quality. The composition of swine slurry varies greatly, its component of main concern is nitrogen. Untreated swine slurry contains considerable amounts of non-stabilized organic matter and high concentrations of ammonium that can reach values of 8 g/L, depending on the farm characteristics (Torrens, 2016). Spreading excess slurry over croplands may result in pollution, mainly by nitrates, of Constructed Wetlands for Pig Slurry Treatment groundwater and eutrophication of surface waters due to phosphorous contents (Armengol and Salgot, 2011). Swine slurry nutrients in excess of crop uptake can accumulate in soils, reaching an oversaturation of nitrates which afterward infiltrate and percolate. Nutrients are lost to either surface or ground waters (Martinez et al, 2009)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
