Bioremediation using Ulva lactuca and Crassotrea gigas

Monika Tsotsorou, Johann Nathan Blom Schnügger, Atanas Dimchev Dilov, Amélie Lapointe, Paola Talarico & Chiara Da San Martino

Studenteropgave: Fagmodulprojekt

Abstrakt

The fast growth of the aquaculture industry worldwide has created a serious concern regarding wastewater management. Untreated aquaculture wastewater usually has high content of nutrients, which can cause harmful effects in the environment such as eutrophication. Eutrophication is caused due to hypernutrification leading to algal blooms and high turbidity and chlorophyll concentration in the water. Several landbased facilities use water recirculation and treat the water on site without contaminating the surrounding environment. However, plenty of facilities still discharge the wastewater into the surrounding body of water and many of them have water runoff to the groundwater. An alternative for reducing nutrient excess is the use of bio filters that can effectively remove nutrients from the water and perhaps even have the potential to generate an extra income for the aquaculture facilities. This experiment was designed to test whether macroalgae and filter feeder organisms can be used to remove the excess ammonium and reduce the turbidity and the presence of microalgae in wastewater from a copepod production facility. The experiment consisted on a treatment where Ulva lactuca was the sole bioremediator, a treatment consisting of Crassostrea gigas, a combined treatment of U. lactuca and C. gigas, and a control treatment. Ammonium concentration, ammonium disappearance rate, turbidity, and chlorophyll biomass were monitored during a 24-hour period. To simulate aquaculture wastewater conditions, the ammonium concentration of the wastewater was raised to approximately 25 μmol L-1 prior to the start of the experiment and Rhodomonas salina was added to increase turbidity and chlorophyll biomass in all treatments. The experiment showed that the algae and the combined algae-oyster treatments were very effective at reducing the ammonium concentration in the water compared to the oyster treatment (p always <0.01), with the ammonium concentration reaching zero after 12 hours in both treatments. The ammonium disappearance rate was highest in the algae treatment and it was significantly different from the control and oyster treatments (p<0.05 and p<0.02, respectively). The system containing algae and oyster was the most effective at reducing the turbidity of the water compared to the other treatments (p always < 0.01). The chlorophyll biomass data were not used during the analysis as many of the measured data were below the detection limits of the used method. Bioremediation using macroalgae and oysters can have a potential use in the aquaculture industry since they appear to be an effective combination in wastewater treatment and economically beneficial to the facilities.

UddannelserBasis - International Naturvidenskabelig Bacheloruddannelse, (Bachelor uddannelse) Basis
SprogEngelsk
Udgivelsesdato28 maj 2017
Antal sider39