تحلیل یکپارچه امکان‌سنجی کاربردهای پایدار فاضلاب صنعتی تصفیه‌شده

Abstract
The utilization of unconventional water resources, particularly treated industrial wastewater, has been increasingly recognized as a sustainable and effective approach to alleviating water stress and enhancing integrated water resource management. In this study, the feasibility of reusing effluent from the Jahanabad Industrial Complex wastewater treatment plant (Meybod, Yazd Province, Iran) was evaluated across four major applications: agricultural irrigation, urban landscape irrigation, discharge into surface waters, and infiltration wells. To this end, a six-month monitoring program was conducted, during which key physicochemical and biological parameters-including Chemical Oxygen Demand (COD), Biochemical Oxygen Demand over five days (BOD₅), pH, temperature (T), Dissolved Oxygen (DO), Chloride (Cl), Total Suspended Solids (TSS), and Electrical Conductivity (EC)-were measured and compared against the permissible limits defined by national standards for each intended use. The findings revealed that several parameters, such as BOD, COD, TSS, and pH, generally complied with national thresholds, indicating potential suitability for certain reuse applications. However, elevated EC values and insufficient DO concentrations imposed significant constraints, particularly for discharge into surface waters. Overall, the analysis identified agricultural irrigation as the most appropriate and practical reuse option for the treated effluent. Nevertheless, the results underscore the need to upgrade treatment processes and enhance system performance to consistently achieve safe and sustainable effluent quality, particularly to safeguard public health and protect the environment
 
Extended Abstract
Background and Objective
Climate change, rapid population growth, urban expansion, and intensified industrial and agricultural activities have reshaped water-use patterns and placed increasing pressure on limited freshwater resources, particularly in arid and semi-arid regions. In many such areas, the widening gap between water availability and demand highlights both the severity of the water crisis and the constraints of existing water-management infrastructure. Projections indicate that this imbalance will continue to grow if current extraction trends persist.
To address these pressures, non-conventional water sources-especially treated municipal and industrial wastewater-have gained attention as viable and sustainable alternatives. When adequately treated, such effluents can support applications including agricultural irrigation and landscape maintenance, thereby conserving high-quality freshwater for domestic and drinking purposes.
Although municipal wastewater reuse is now widely practiced, industrial effluents require more stringent evaluation due to potentially hazardous constituents such as heavy metals and pathogenic microorganisms. Ensuring safe reuse, therefore, demands continuous monitoring of effluent quality and periodic assessment of treatment performance, with system upgrades implemented whenever standards are not met.
This study examines the treated effluent discharged from the wastewater treatment plant of the Jahan-Abad Industrial Park in Meybod, Yazd Province, Iran, to evaluate its suitability for safe and sustainable reuse and identify measures to enhance treatment efficiency where needed.
 
Methodology
This study employed an analytical–descriptive approach. Over a six-month monitoring period, key effluent parameters-Chemical Oxygen Demand (COD), five-day Biochemical Oxygen Demand (BOD₅), pH, temperature (T), dissolved oxygen (DO), chloride (Cl), total suspended solids (TSS), and electrical conductivity (EC)-were measured at the final discharge point of the wastewater treatment plant serving the Jahanabad Industrial Park in Meybod (Yazd Province). The recorded values were compared with nationally established standards for four intended uses: agricultural irrigation, landscape irrigation, discharge to surface waters, and infiltration through absorption wells. This comparison enabled assessment of both treatment performance and the effluent’s suitability for safe reuse.
The treatment facility, located in an arid to semi-arid region, consists of a primary stage (screening, grit removal, and aeration) followed by secondary treatment based on the activated-sludge process, supplemented by supporting units to improve effluent stability. The system aims to reduce organic and inorganic pollutants to levels compatible with multiple reuse pathways.
The updated results indicate that chloride concentrations fall within acceptable limits for agricultural use, though additional management is advisable for salt-sensitive crops. EC values reflect moderate salinity, highlighting the need for periodic soil monitoring to prevent long-term salt accumulation. BOD₅ and COD levels demonstrate effective removal of organic matter, placing the effluent within suitable ranges for both agricultural and landscape irrigation. DO concentrations are adequate to avoid downstream anaerobic conditions, and TSS levels meet criteria for discharge to surface waters and infiltration systems, confirming efficient solids removal. The near-neutral pH and locally consistent temperature further support compatibility with various reuse applications. Overall, the findings confirm that the treated effluent is suitable for agricultural and green-space irrigation as well as discharge to surface waters and absorption wells, provided that chloride and salinity are managed to avoid impacts on sensitive vegetation.
 
Findings
The evaluation of treated effluent from the Jahanabad Industrial Park wastewater treatment plant indicates that its suitability varies across different reuse applications. For surface-water discharge and infiltration wells, chloride and pH meet regulatory limits, but BOD₅, COD, DO, and TSS exceed acceptable thresholds, suggesting that further treatment is necessary to reduce organic load and enhance dissolved oxygen.
In agricultural irrigation, most parameters—including chloride, pH, temperature, BOD₅, COD, and TSS—fall within acceptable limits, while elevated EC and insufficient DO may increase soil salinity and limit oxygen availability, potentially affecting plant health. Additional monitoring of fecal coliforms is also recommended before large-scale reuse.
For landscape irrigation, chloride, pH, DO, COD, and temperature comply with guidelines, whereas BOD₅ and TSS exceed limits, posing risks of organic and suspended-solid accumulation in soils.
Overall, chloride and pH remain within permissible ranges for all four reuse scenarios. COD and BOD₅ surpass limits only for surface-water discharge and infiltration, while EC, BOD₅, and TSS require improvement for green-space irrigation. These findings highlight the need for targeted treatment enhancements to reduce organic load, manage salinity, and improve oxygen levels, ensuring safe and sustainable effluent reuse.
 
Conclusion
The quality assessment of the effluent from the Jahanabad Industrial Park treatment plant in Meybod indicates that agricultural irrigation is the most compatible reuse option, as a larger number of parameters fall within acceptable limits compared with other applications. Landscape irrigation ranks next, while discharge to surface waters and infiltration wells show lower compliance and are therefore less suitable.
To improve effluent quality and strengthen the treatment system, currently based on the activated-sludge process-the use of a trickling filter is recommended as an effective complementary unit. This biological method employs layered media that support aerobic microbial growth, enabling efficient reduction of organic pollutants as wastewater passes through the filter bed.
The trickling filter offers high treatment efficiency, relatively low operational costs, and strong potential as a pretreatment step in industrial and municipal systems. Its incorporation can substantially decrease key parameters such as BOD, COD, and TSS, thereby enhancing the reliability and safety of effluent reuse across various applications.