نوع مقاله : مقاله کامل علمی پژوهشی
نویسندگان
1 دانشجوی سابق کارشناسی ارشد گروه مهندسی آب دانشگاه شهرکرد، ایران
2 دانشگاه شهرکرد، دانشکده کشاورزی، گروه مهندسی اب
3 گروه مهندسی آب، دانشکده کشاورزی، دانشگاه شهرکرد، ایران
4 گروه کشاورزی، دانشگاه پیام نور، ایران
چکیده
کلیدواژه‌ها
عنوان مقاله [English]
نویسندگان [English]
Background and objectives: In drip irrigation systems, the low surface reactivity of the sand filter for physical-chemical treatment led to the use of other filter media that increase the retention capacity of wastewater contaminants along with the sand. The purpose of this study was firstly to compare the application of sand and geotextile with zeolite in filters to reduce nitrate pollution in wastewater and secondly to compare the quality parameters of Shahrekord University effluent with international standards.
Materials and Methods: This research was conducted at Shahrekord University in 2014-2015. The wastewater used in this project was prepared from an observation well located near the east door of Shahrekord University. In order to investigate the nitrate status, a factorial experiment was performed in a completely randomized design with three replications. Treatments include control treatment Ctrl (sand without application of zeolite), geotextile without application of zeolite J, sand-geotextile without application of zeolite SJ, sand with zeolite SZ, geotextile with zeolite JZ, and geotextile sand with zeolite. The treatments were poured into cylindrical columns made of PVC tubes. Inlet effluent nitrate and wastewater were measured with a spectrophotometer. The total suspended solid, EC, pH, sodium, calcium and magnesium in the effluent were determined and compared with the standards. Statistical analysis was performed using SAS software.
Results: The results showed that the filters had a significant effect on the effluent nitrate passed from the columns (P<0.01). JZ, SJZ, and SZ treatments showed the highest nitrate reduction with 57, 55, and 52%, respectively. Sand treatment did not affect nitrate as expected. Measurements showed that the amount of nitrate in Shahrekord University effluent for irrigation was less than the allowable amount of some organizations, but was not suitable for irrigation according to the FAO standard. Also, the amount of EC (1.02 dS/m) and suspended solid (109.6 mg/L) was too much for irrigation according to most standards, but the pH and SAR of the effluent were sufficient to be used for irrigation. The minimum and maximum pH values were 7.2 and 8.03, respectively, which were lower than the maximum value of all standards. The measured SAR of the effluent entering the filters was 2.14, which was allowed according to the standards in terms of application in irrigation.
Conclusion: This study showed that sand filters alone did not affect the amount of suspended load in the effluent, but using geotextiles and zeolite in sand filters can reduce nitrate pollution from effluent. The amount of sodium, and total calcium and magnesium in the effluent was higher than the allowable amount for use in irrigation according to the standards of the US Environmental Protection Agency. But the amount of sodium absorption ratio was less than the allowable amount for use in irrigation according to all standards.
کلیدواژه‌ها [English]
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