Poor sanitation costs Kenya about 1-2% of its GDP per year, emphasising the crucial need for sustainable solutions. Source separation of excreta is a viable option because it allows for nutrient recovery. However, its direct use as a fertiliser is limited by urea hydrolysis, which elevates pH, causes nitrogen loss, and generates ammonia. Stabilisation is thus essential to retain nitrogen while reducing microbial activity. Simultaneously, Kenya struggles with fruit and vegetable waste disposal, which contributes to environmental damage. The study addressed the stabilisation and treatment of human urine using lactic acid produced from the anaerobic fermentation of fruit and vegetable peels (mango, pineapple, banana, orange, and cabbage) as a sustainable and potential source of nitrogen fertiliser. Lactic acid was produced after three-day fermentation of samples prepared at 1:1 and 1:2 substrate-to-water ratios and incubated at 34°C, 37°C, and 40°C. Qualitative analysis of the sample using Liquid Chromatography-Mass Spectrometry (LCMS/MS) showed sharp, pronounced peaks at 3.691 minutes each, indicating high concentration of lactic acid (LA). The Lactic acid was then quantified spectrophotometrically at 410 nm. The highest LA concentration was found to be 1304.7 mg/L, for the sample fermented at 37°C and lowest for sample at 40°C (538 mg/L). Urine samples were then treated with the resulting lactic acid for 4, 7, and 10 days. The pH of the samples was measured to determine lactic acid's efficiency in inhibiting urea hydrolysis. The resulting pH of the urine samples ranged from 3.6-4.2, indicating lactic acid action on urine to inhibit hydrolysis. An ANOVA Tukey HSD test showed that both the p-values for Temperature difference (p = 0.00) for 37°C and 40°C and (p = 0.003) for 40°C and 34°C, and different days’ interval (p = 0.001) for 4-10 days and (p = 0.00) for 7-10 days were statistically significant. The nitrogen content in the urine was determined using the Kjeldahl method while the MacConkey Agar tested pathogen inactivation through identifying E. coli growth. Lactic acid treatment significantly reduced the pH of urine samples across all settings, with the greatest pH reduction at 37°C (3.4). Nitrogen analysis revealed that samples treated at 37°C in a 1:1 ratio had the most nitrogen concentration (2450 mg/L). A Tukey's HSD test comparing the mean nitrogen concentrations across different treatment days and temperature (4, 7, and 10 days), showed significant difference in concentration over the number of days, especially at 10 days (p = 0.001) and for each of the temperature settings (p = 0.000, 0.001, 0.002). Furthermore, lactic acid had strong antibacterial action, inhibiting E. coli growth. This study revealed the ability of lactic acid from organic waste to stabilise urine, preserve nitrogen content, and ensure pathogen safety, supporting sustainable sanitation practices and resource recovery in agriculture