This chapter presents a thorough 3-year exploration of the efficacy of water lettuce (Pistia stratiotes) macrophyte ponds for the treatment of wastewater from a typical rubber processing industry, alongside the utilization of treated effluent as biofertilizer. Initial assessment of wastewater quality involved monthly data collection and analysis over a year to establish baseline parameters, identifying several constituents surpassing permissible limits, notably conductivity, nitrates, pH, biological oxygen demand (BOD), turbidity, phosphate, total dissolved solids (TDS), and total suspended solids (TSS). Subsequently, water lettuce was introduced, covering 50% of the pond surface, and monthly monitoring of effluents ensued, assessing various chemical, physical, and biological parameters. Treatments were implemented in the ponds with retention periods ranging from 2 to 12 weeks across three inoculation phases. The findings revealed a notable reduction in most contaminants, bringing them within acceptable limits, albeit exceptions were observed for TSS and turbidity. Moreover, the treated effluent demonstrated positive effects on maize plant growth, evidenced by enhancements in plant height, stem girth, leaf area, and biomass yield. Notably, the maximum plant height of 117.5 ± 7.6 cm was recorded at 63 days post-planting under the second treatment regimen. The average cob weight from the second treatment group stood at 46.2 ± 6.1 g, contrasting with 21.3 ± 6.7 g from the control group.