Ammonia volatilization in duckweed-based and algae-based stabilization containers

Abstract

Sustainable technologies for wastewater treatment, within the economic and technological capabilities of developing countries, need to be developed. These technologies should aim to reuse not only water but also the nitrogen content. Both waste stabilization ponds (WSP) and duckweed-covered ponds offer possibilities for nitrogen reuse. The aim of this research is to assess the ammonia volatilization in algae - based (ABC) and duckweed - based containers (DBC). In laboratory batch experiments, duckweed (Limna gibba)-based and algae-based wastewater containers have been monitored during 15 days of incubation in three experiments with different initial total nitrogen concentrations of 50 (experiment 1), 100 (experiment 2), and 150 mg-N/l (experiment 3). Clear differences in environmental conditions were observed. Higher pH values were measured in algae-based due to algae photosynthetic activity compared to duckweed based containers where duckweed mat prevent sunlight penetration and hence algae development. In algae, based pH range was between 8.3 to 8.55, 7.88 to 8.57, and 7.92 to 8.54 in experiments 1, 2, and 3 respectively, and 7.44 to 8.09, 7.3 to 7.46, and 7.37 to 7.8 in duckweed based-containers. Depending on the initial nitrogen concentrations, duckweed-based containers removed between 33%-60% of total nitrogen, between 3%-7% of nitrogen loss by ammonia volatilization, and between 2%-16% of nitrogen loss by denitrification from the wastewater. While, algae based containers removed between 22%-48% of total nitrogen, between 19%-22% of total nitrogen by ammonia volatilization, and between 1 % and 24% of nitrogen by denitrification. This study demonstrates which process is responsible of more nitrogen loss in ABC and DBC. The effect of nitrogen concentration in ammonia volatilization and denitrification in two system.