Removal of oxytetracycline and ofloxacin in wastewater by microalgae-bacteria symbiosis for bioenergy production

The development of microalgae-bacteria symbiosis for treating wastewater is flourishing owing to its high biomass productivity and exceptional ability to purify contaminants. A nature-selected microalgae-bacteria symbiosis, mainly consisting of Dictyosphaerium and Pseudomonas, was used to treat oxytetracycline (OTC), ofloxacin (OFLX), and antibiotic-containing swine wastewater. Increased antibiotic concentration gradually reduced biomass productivity and intricately changed symbiosis composition, while 1 mg/L OTC accelerated the growth of symbiosis. The symbiosis biomass productivity reached 3.4-3.5 g/L (5.7-15.3 % protein, 18.4-39.3 % carbohydrate, and 2.1-3.9 % chlorophyll) when cultured in antibiotic-containing swine wastewater. The symbiosis displayed an excellent capacity to remove 76.3-83.4 % chemical oxygen demand, 53.5-62.4 % total ammonia nitrogen, 97.5-100.0 % total phosphorus, 96.3-100.0 % OTC, and 32.8-60.1 % OFLX in swine wastewater. The microbial community analysis revealed that the existence of OTC/OFLX increased the richness and evenness of microalgae but reduced bacteria species in microalgae-bacteria, and the toxicity of OFLX to bacteria was stronger than that of OTC.

Automated summary

The development of microalgae-bacteria symbiosis for treating wastewater is thriving due to its high biomass productivity and exceptional ability to purify contaminants. A nature-selected microalgae-bacteria symbiosis, primarily consisting of Dictyosphaerium and Pseudomonas, was utilized to treat wastewater containing oxytetracycline (OTC), ofloxacin (OFLX), and antibiotics. Higher antibiotic concentration gradually reduced biomass productivity and altered the composition of the symbiosis, while a low concentration of OTC accelerated symbiosis growth. The symbiosis exhibited excellent capacity in removing various pollutants in swine wastewater, including chemical oxygen demand, total ammonia nitrogen, total phosphorus, OTC, and OFLX.