Abstract:
The management of wastewater from carwash centers continues to pose a significant global challenge, with the
quest for treatment methods that are both effective and economical proving particularly daunting. This un
derscores the importance of exploring natural materials for wastewater treatment. However, knowledge
regarding the efficacy of bio-functionalized wheat straw and pistachio shells specifically for carwash wastewater
treatment remains limited. This study explored the potential of wastewater treatment using bio-functionalized
agricultural waste materials, specifically wheat straw and pistachio shells. Experimental setups included treat
ment plants using wheat straw alone, pistachio shell alone, a mixture of both, and a series connection. Removal
efficiencies across various water quality parameters revealed the series connection as the most effective treat
ment, achieving exceptional removal efficiencies for critical parameters such as fat, oil, and grease, total sus
pended solids, and turbidity. The Mixture treatment demonstrated synergistic effects, surpassing individual
treatments in removing contaminants such as Arsenic, Biochemical Oxygen Demand, cadmium, Chemical Oxy
gen Demand, fluorides, ammonia nitrogen, and surfactants. More precisely, the series treatment setup resulted in
nearly complete removal efficiency, approximately 100%, for Fat, Oil, and Grease, turbidity, and total suspended
solids in the wastewater samples. The treatment setup using only wheat straw achieved removal efficiencies
between 41.3% and 83.3%, whereas the setup using only pistachio shell achieved removal efficiencies ranging
from 43.3% to 89.1%. Statistical analyses confirmed the significance of observed differences, with isotherm and
kinetic models providing valuable insights into adsorption characteristics. Freundlich constants ranged from 3.6
to 12.38, Moreover, the integrated treatments consistently outperformed individual ones, as demonstrated by
Water Quality Index values. The Water Quality Index values ranged from 2114.26 for raw wastewater, classified
as “unsuitable for drinking,” to 154.47 for the series connection of wheat straw and pistachio shell, indicating a
significant improvement in water quality.
