Constructed wetland mesocosms for the treatment of diluted sugarcane molasses stillage from ethanol production using Pontederia sagittata

Plants in constructed wetlands help to treat agricultural processing wastewater

“…evaluated the performance of a subsurface-flow wetland (20 feet long, 8 feet wide and 4 feet deep) in treating winery process wastewater flows ranging from 80 to 170 cubic meters per day at organic loads of 600 to 45,000 milligrams COD per liter (mg COD/l), and measured average removal rates of 98% for COD and 97% for total suspended solids (TSS) when combining the constructed wetland with an upflow sand prefilter. The system also Olguín et al (2008) achieved similar results from greenhouse-based, fiberglass, subsurface "flumes" (long, narrow boxes 10 feet long, 1 foot wide and 1.6 feet deep), used to treat diluted molasses process wastewater with 2.5-or 5-day HRTs and an average inlet concentration of 1,184 mg COD/l (534 mg BOD 5 /l). After 30 to 40 days of plant (Pistia sagittata) establishment, the planted flumes achieved average removal rates of 80.2% for COD, 87.3% for BOD 5 , 76.1% for total Kjeldahl nitrogen (TKN, the sum of organic nitrogen, ammonia and ammonium) and 68.6% for sulfate during the next month.…”

“…In the subsurface system, 3 to 4 weeks were sufficient for plant establishment to achieve the steady removal rates reported by Olguín et al (2008). Overall, COD removal rates indicate that the use of constructed-wetland systems in the drainage canals leaving sugarcane processing facilities should be advantageous for improving downstream water quality.…”

“…To determine the characteristics of sugarcane process wastewater in Mexico, in March 2007 we compared wastewater from a typical processor, Ingenio La Gloria, located on the coast south of Veracruz (Olguín et al 2008), to sugarcane process wastewater in India and Brazil, and process wastewater from a California winery (table 1). In Mexico, sugarcane process wastewater is typically diluted 10 to 100 times with canal water prior to reuse for irrigation or release into drainage channels, making it similar in quality to that reported for Brazil.…”

“…In the greenhouse studies, we also considered the rate of plant growth and its effect on process wastewater (Olguín et al 2008). In California, where plants are normally allowed to establish for about a year prior to the introduction of process wastewater, we monitored two planted and unplanted pairs of constructed wetlands at wineries on the Central Coast.…”

“…At the Instituto de Ecología near Xalapa, Mexico, we employed the greenhouse facilities, constructed-wetland flumes and methods, all as described by Olguín et al (2008). Duplicate flumes were used for each of the three different treatment systems and HRTs.…”