Enhanced microalgae-bacteria symbiosis for domestic garbage leachate treatment: Optimization and life cycle assessment

Domestic garbage leachate (DGL) poses severe environmental threats due to its complex organic toxins and high chromaticity, limiting conventional treatment efficacy. To overcome these toxicity limitations, this study developed a dual-waste valorization strategy using rural sewage (RS)-diluted DGL for microalgal cultivation via adaptive cultivation. The microalgal density reached 2.88×10 7 cells/mL in the LS5 group diluted 5-fold by RS. Through integrated optimization combining single-factor experiments (culture modes and light spectra) and response surface methodology (cultivation cycle, inoculum density, light intensity), the optimal parameters were determined: mixotrophic cultivation at an initial density of 6.5×10 6 cells/mL in non-sterilized LS5 under continuous white light (2942 lux) for 20 d. Life cycle assessment (LCA) revealed that DGL utilization avoids upstream production burdens associated with conventional nutrients versus conventional medium, with water consumption and energy identified as primary environmental impact contributors. This work demonstrates how technological innovation in waste-to-resource conversion enhances environmental sustainability and circular economy development, with LCA confirming broader ecological advantages beyond localized wastewater treatment. • Microalgal screening-domestication-single/multi-factor optimization was performed. • Chlorella exhibited the highest nutrient removal capacity in a DGL: RS of 1:4. • White light promoted algal density, while blue light increased the cell diameter. • LCA revealed significant environmental impacts from energy/water consumption.