Metagenomic sequencing of water and sediment in natural composite oxidation ponds.

We hypothesize the natural composite oxidation ponds system operates stably, forming a dominant microbial community structure focused on denitrification. The specific objectives of this study were to:1. Design and construct a simple, low-cost, livestock treatment system suitable for rural mountainous areas. 2. Monitoring the variations in nitrogen and phosphorus levels between ponds and NCOPS removal efficiency. 3. The nitrogen removal mechanism of the microbial in the system, including microbial community composition, identification of key species, and nitrogen removal pathway.