Water hyacinth, water lettuce and parrot's feather plants were examined for their ability to remove nutrients from aquaculture wastewater at two retention times. During the experiment, the aquatic plants grew rapidly and appeared healthy with green color. At hydraulic retention times (HRTs) of 6 and 12 days, the average water hyacinth, water lettuce and parrot's feather yields were 83, 51 and 51 g (dm) m-2 and 49, 29 and 22 g (dm) m-2 , respectively. The aquatic plants were able to significantly reduce the pollution load of the aquaculture wastewater. The TS, COD, NH 4 +-N, NO 2-N, NO 3-N and PO 4 3-P reductions ranged from 21.4 to 48.0%, from 71.1 to 89.5%, from 55.9 to 76.0%, from 49.6 to 90.6%, from 34.5 to 54.4% and from 64.5 to 76.8%, respectively. Generally, the reductions increased with longer retention times and were highest in compartments containing water hyacinth followed by compartments containing water lettuce and parrot's feather. In terms of COD, NO 3-N and PO 4 3-P, the effluent leaving the hydroponics system was suitable for reuse in aquaculture. However, the effluent had slightly high levels of TS, NH 3-N, NO 2-N and pH after treatment.

Hydroponically grown wheat, barley and oats were examined for their ability to remove nutrients from aquaculture wastewater. Wheat, barley and oats seeds were germinated in water in a hydroponics system. The seedlings then received wastewater from an aquaculture system stocked with Arctic charr. During the experiment, the crops grew rapidly and fairly uniformly and showed no signs of mineral deficiency although fungal growth was evident. The average crop heights and yields at harvest were 19.0, 25.5 and 25.2 cm and 64, 59 and 42 t ha^-1 for wheat, barley and oats, respectively. The hydroponically grown wheat, barley and oats were able to significantly reduce the pollution load of the aquaculture wastewater. The TS, COD, NH₄⁺-N, NO₂^--N, NO₃^--N and PO₄^3--P reductions ranged from 53.3 to 57.7%, from 55.7 to 78.7%, from 76.0 to 80.0% from 85.1 to 92.9%, from 62.1 to 79.3% and from 74.1 to 93.0%, respectively. The compartments containing barley produced the highest quality effluent, which was suitable for reuse in aquaculture operations. The average TS, COD, NH₄⁺-N, NO₂^--N, NO₃^--N and PO₄^3--P concentrations and pH of the final effluent from the compartments containing barley were 442, 64, 0.50, 0.02, 5.89 and 0.61 mg L^-1 and 6.65, respectively. The nutritive value of the three wastewater grown crops was assessed to determine the suitability of using the plants as a component in fish feed. The three terrestrial crops meet the energy, fat, Ca, Mg, P, Na, S and Mn dietary requirements of aquatic animals, exceed the carbohydrate, crude fiber, Cl, K, Cu, Fe, Se and Zn requirements of fish and shellfish and do not contain sufficient amounts of protein to meet the dietary requirements of fish and shellfish. The crops will require supplementation with a high protein source that contains low concentrations of carbohydrates, crude fiber, Cl, K, Cu, Fe, Se and Zn. Common protein sources that could be used for supplementation included fishmeal, bone meal and blood meal

Barley was examined for its ability to remove nutrients from aquaculture wastewater. The effects of seed sterilization using ethanol and bleach and seed density on germination and plant growth were investigated. Surface sterilization of barley seeds had a negative impact on germination. Increasing the ethanol concentration and/or the bleach concentration reduced the germination percentage. Barley seeds were first germinated in water in the hydroponics system. The seedlings then received wastewater from an aquaculture system stocked with Arctic charr. During the experiment, the crops grew rapidly and fairly uniformly and showed no signs of mineral deficiency or disease. The average crop height at harvest was 25.5 cm and the yield varied from 25 to 59 t ha 1 , depending on the seed density. The hydroponically grown barley was able to significantly reduce the pollution load of the aquaculture wastewater. The TS, COD, NH 4 + -N, NO 2 --N, NO 3 --N, and PO 4 3--P reductions ranged from 52.7 to 60.5%, from 72.9 to 83.1%, from 76.0 to 76.0%, from 97.6 to 99.2%, from 76.9 to 81.6% and from 87.1 to 95.1%, respectively. However, the effluent produced from the hydroponics system had slightly higher levels of TS (420-485 mg L 1 ) than the 480 mg L 1 recommended for aquatic animals. A sedimentation/filtration unit should be added to the hydroponics system.

The treatment of grease filter washwater by chemical coagulation and sedimentation using different dosages of aluminum sulfate was investigated. Pollutant removal efficiency was measured in terms of total solids, pH and optical density. The process was found to be effective at the room temperature and the filter washwater pH (9.5). The optimum aluminum sulfate dosage was 2 g/L. The treatment reduced the total solids of the wastewater by 89.6%, and produced a supernatant with a pH of 4.15 and an optical density of 0.194 nm. A fully automated prototype was then constructed for the treatment of grease filter washwater. Three distinct layers were formed in the system (fat, liquid and sludge) and each was removed separately. The system successfully recovered over 80% recyclable water with a quality comparable to that of tap water. The combined mixture of sludge and fat (20%) contained high levels of heavy metals and was not suitable for bioconversion into value added product. However, dewatering the sludge using vacuum filtration reduced its volume to 0.8% of the original volume of washwater. As a result, about 99.2% of the washwater (treated water) is recycled in the washing operation

A surface flow wetland was constructed in the Burnside Industrial Park, Dartmouth, Nova Scotia, to treat stormwater runoff from the surrounding watersheds which are comprised primarily of commercial properties and two former landfills. The aim was to protect a freshwater ecosystem that consists of a 4.6 km long brook and two lakes. The ability of the constructed wetland to retain iron and manganese from the influent water was investigated and the change in pH of the water as it flowed through the cells was assessed. In 2004, the total iron removal efficiency of the constructed wetland ranged from a low of 47.