Synchronized urban wastewater treatment and biomass production using duckweed Lemna gibba L

摘要

This work compiles results of utilizing duckweed Lemna gibba L in sewage wastewater treatment and converting wastewater nutrients into protein and carbohydrate rich weed biomass. A total of four different strengths of wastewater (100, 75, 50 and 25%) were used to build experimental setups and changes in chemical properties of wastewater were measured at the end. L gibba L. caused a decrease in pH (9-13%), EC (13-26%), NO3 -N (42-64%), SO4~(-2) (35-82%), total phosphorus (37-54%), totNa (44-75%), _(tot)K (45-76%) and _(tot)Ca (51-72%). The biomass yield in 1. gibba L ranged between 132.62 and 200.95 g/m~2 day (fresh weight) or 23.87 and 36.17 g/m~2 day (dry weight); about 24.6-36.17% higher than initial level in all experimental setups. The weed biomass was 24.6-52.8% higher than initial level in all set-ups. The yield rate of protein and carbohydrate ranged 1.19-1.95 g/m~2 day (dry weight) and 22.72-35.58 g/m~2 day (dry weight), respectively in duckweed systems. The high carbohydrate and protein yield in L gibba advocates the utility of the weed in animal feed and bioethanol production. Results suggested that L gibba can be utilized effectively for designing of a synchronized wastewater treatment and biomass harvesting system.