Carbon Reduction and Pollutant Abatement by a Bio-Ecological Combined Process for Rural Sewage

Area of Science:

• Environmental Engineering
• Wastewater Treatment
• Ecological Engineering

Background:

• Rural domestic wastewater poses pollution and carbon emission challenges.
• Seasonal changes significantly affect wastewater treatment processes.
• Existing bio-ecological systems require optimization for efficiency and resource utilization.

Purpose of the Study:

• To evaluate a combined bio-ecological wastewater treatment process under seasonal variations.
• To assess pollution reduction and carbon abatement in rural wastewater.
• To explore methods for enhancing treatment efficiency and resource utilization.

Main Methods:

• Construction of a combined process: regulating pond, biological filter, subsurface flow constructed wetland, and ecological purification pond.
• Monitoring of influent and effluent water quality, and pollutant treatment characteristics.
• Analysis of microbial community structure in constructed wetlands.

Main Results:

• Average removal rates for COD, TN, and NH3-N were higher in summer (87.57%, 72.18%, 80.98%) than in winter (77.46%, 57.52%, 64.48%).
• Constructed wetlands showed high TN treatment contribution but were seasonally impacted.
• Microbial communities shifted seasonally, with Proteobacteria, Acidobacteria, and Chloroflexi decreasing and Firmicutes, Bacteroidetes, and Planctomycetota increasing from summer to winter.

Conclusions:

• Significant seasonal differences exist in the performance of the bio-ecological wastewater treatment system.
• Adding external carbon sources (e.g., sludge fermentation, rice straw) is recommended to improve treatment and resource utilization.
• Dominant microbial phyla in constructed wetlands are crucial for pollutant degradation, but their abundance is influenced by seasonal changes.