اثر کاربرد دو ترازی صفحات ژئوکمپوزیت بر ویژگی‌های شیمیایی و بیوشیمیایی خاک در شرایط استفاده از فاضلاب

در ﭘﮋوﻫﺶ ﺣﺎﺿﺮ ﺗﻐﯿﯿﺮات وﯾﮋﮔﯽﻫﺎی ﺷﯿﻤﯿﺎﯾﯽ ﺷﺎﻣﻞ ph، ﻫﺪاﯾﺖ اﻟﮑﺘﺮﯾﮑﯽ، ﻣﺠﻤﻮع ﮐﻠﺴﯿﻢ و ﻣﻨﯿﺰﯾﻢ، ﮐﺮﺑﻨﺎت و ﺑﯽﮐﺮﺑﻨﺎت و ﻧﯿﺘﺮات و وﯾﮋﮔﯽ ﺑﯿﻮﺷﯿﻤﯿﺎﯾﯽ ﮐﻠﯿﻔﺮم ﻣﺪﻓﻮﻋﯽ ﺧﺎک ﺗﺤﺖ ﺗﺄﺛﯿﺮ اﺳﺘﻔﺎده از ﭘﺴﺎب داﻧﺸﮕﺎه ﺷﻬﺮﮐﺮد ﺑﺎ اﺳﺘﻔﺎده از ﺳﺎﻣﺎﻧﮥ آﺑﯿﺎری زﯾﺮﺳﻄﺤﯽ ﻫﻤﺮاه ﺑﺎ ﺻﻔﺤﺎت ژﺋﻮﮐﻤﭙﻮزﯾﺖ ﻣﻮرد ﺑﺮرﺳﯽ ﻗﺮار ﮔﺮﻓﺖ. ﺑﺮای اﻧﺠﺎم ﭘﮋوﻫﺶ ﺣﺎﺿﺮ از ﺻﻔﺤﺎت ژﺋﻮﮐﻤﭙﻮزﯾﺖ ﺑﻪﻋﻨﻮان ﻻﯾﮥ آﺑﺪه و ﻻﯾﮥ زﻫﮑﺶ اﺳﺘﻔﺎده ﺷﺪ. ﺗﯿﻤﺎرﻫﺎی ﭘﮋوﻫﺶ ﺷﺎﻣﻞ دو ﻓﺎﺻﻠﮥ 70 و 35 ﺳﺎﻧﺘﯽﻣﺘﺮ ﺑﯿﻦ ﻻﯾﮥ آﺑﺪه و ﻻﯾﮥ زﻫﮑﺶ ﺑﻮد. در ﻫﺮ دو ﺗﯿﻤﺎر، ﻻﯾﮥ آﺑﺪه ﺑﻪ ﻓﺎﺻﻠ ﮥ 40 ﺳﺎﻧﺘﯽﻣﺘﺮی از ﺳﻄﺢ ﺧﺎک در زﻣﯿﻦ ﻗﺮار ﮔﺮﻓﺖ. ﺗﺰرﯾﻖ ﭘﺴﺎب ﺑﻪ داﺧﻞ ﺧﺎک ﻃﯽ 12 ﻧﻮﺑﺖ و ﺑﺎ ﺗﻨﺎوب ﻫﻔﺘﮕﯽ اﻧﺠﺎم ﺷﺪ. در اﺑﺘﺪا و اﻧﺘﻬﺎی دور ه‌ ﻣﻄﺎﻟﻌﻪ از دو ﻋﻤﻖ ﺻﻔﺮ ﺗ ﺎ 40 و 40 ﺗﺎ 80ﺳﺎﻧﺘﯽ ﻣﺘﺮی ﺧﺎک ﻧﻤﻮﻧﻪ ﺑﺮداری و ﻣﯿﺰان ph، ﻫﺪاﯾﺖ اﻟﮑﺘﺮﯾﮑﯽ، ﻣﺠﻤﻮع ﮐﻠﺴﯿﻢ و ﻣﻨﯿﺰﯾﻢ، ﮐﺮﺑﻨﺎت و ﺑﯽ ﮐﺮﺑﻨﺎت، ﻧﯿﺘﺮات و ﮐﻠﯿﻔﺮم ﻣﺪﻓﻮﻋﯽ اﻧﺪازه ﮔﯿﺮی ﺷﺪ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ ﺗﻐﯿﯿﺮات ﺗﻤﺎﻣﯽ ﭘﺎراﻣﺘﺮﻫﺎ در ﻃﻮل دوره در ﺧﺎک ﻣﻌﻨﺎدار ﻧﺒﻮد. اﻟﺒﺘﻪ ﻧﺘﺎﯾﺞ ﻧﺸﺎن از اﻓﺰاﯾﺶ ﻫﺪاﯾﺖ اﻟﮑﺘﺮﯾﮑﯽ، ﮐﺮﺑﻨﺎت و ﺑﯽﮐﺮﺑﻨﺎت، ﮐﻠﯽﻓﺮم ﮐﻞ و ﮐﻠﯽ ﻓﺮم ﻣﺪﻓﻮﻋﯽ در ﺧﺎک در اﻧﺘﻬﺎی دوره ﻧﺴﺒﺖ ﺑﻪ اﺑﺘﺪای دوره داﺷﺖ. ﻣﯿﺰان ph ﺧﺎک در ﺗﯿﻤﺎرﻫﺎی d70 و d35 ﺑﻪ ﻃﻮر ﻣﯿﺎﻧﮕﯿﻦ ﺑﻪ ﺗﺮﺗﯿﺐ 2/29 و 2/32 درﺻﺪ ﻧﺴﺒﺖ ﺑﻪ اﺑﺘﺪای دوره ﮐﺎﻫﺶ ﯾﺎﻓﺖ. ﻣﺠﻤﻮع ﮐﻠﺴﯿﻢ و ﻣﻨﯿﺰﯾﻢ ﺧﺎک ﻧﯿﺰ در ﺗﯿﻤﺎرﻫﺎی d70و d35ﺑﻪ ﻃﻮر ﻣﯿﺎﻧﮕﯿﻦ 6/66 و 8 /48 درﺻﺪ ﻧﺴﺒﺖ ﺑﻪ اﺑﺘﺪای دوره ﮐﺎﻫﺶ ﯾﺎﻓﺖ وﻟﯽ ﻫﻤﺎن ﻃﻮر ﮐﻪ اﺷﺎره ﺷﺪ، اﯾﻦ ﺗﻔﺎوت ﻣﻌﻨﺎدار ﻧﺒﻮد. در ﻣﺠﻤﻮع ﮐﺎرﺑﺮد ﺻﻔﺤﺎت ژﺋﻮﮐﻤﭙﻮزﯾﺖ ﺑﺮای ﺗﺼﻔﯿﮥ زﻣﯿﻨﯽ در ﻃﯽ دوره‌ آزﻣﺎﯾﺶ ﺗﺄﺛﯿﺮ ﻣﻨﻔﯽ ﺑﺮ وﯾﮋﮔﯽﻫﺎی ﺷﯿﻤﯿﺎﯾﯽ و ﺑﯿﻮﺷﯿﻤﯿﺎﯾﯽ ﺧﺎک ﻧﺪاﺷﺖ و ﺑﺎ ﮐﻨﺘﺮل و ﭘﺎﯾﺶ ﺳﺎﯾﺮ ﭘﺎراﻣﺘﺮﻫﺎ، اﯾﻦ روش، ﺑﺪون ﻧﮕﺮاﻧﯽ از آﻟﻮدﮔﯽ ﺧﺎک ﻣﯽﺗﻮاﻧﺪ اﺳﺘﻔﺎده ﺷﻮد.

the effect of using bi-level geocomposite sheets on the soil chemical and biochemical characteristics under wastewater reuse

introductionreusing wastewater in agriculture, especially for crop irrigation, is one of the most important options to alleviate the water shortage problem and reduce environmental pollution through land-based wastewater treatment. the presence of organic matter, nutrients, and fecal matter in sewage effluent enhance the activity, survival, growth, and development of bacteria. these are factors that contribute to soil coliform contamination under irrigation with sewage. subsurface irrigation is one of the proven methods that can minimize soil contamination compared with other methods of irrigation. studies have shown that subsurface irrigation systems with geotextiles can reduce environmental pollution and the risk of soil and plant contamination when using wastewater. so far, many studies have investigated the effects of wastewater application on soil characteristics, but there is limited information on the effect of wastewater application using subsurface textile irrigation (ssti) systems on soil properties. in this study, the effects of wastewater application through subsurface irrigation with geocomposite sheets on the chemical and biochemical characteristics of soil were investigated. specifically, the changes in the chemical and biochemical characteristics of soil due to the application of shahrekord university wastewater using subsurface irrigation with geocomposite sheets were analyzed.materials and methodsthis research was conducted as a factorial experiment based on a completely randomized design with three replications. the studied factors included the measurement location at two levels: above (zero to 40 cm) and below (40-80 cm) the injection layer, and the distance of the drain from the injection layer at two levels: 35 (d35) and 70 cm (d70). for the experiment, trenches (each 4 m long, 40 cm wide, and 75 (d35) and 110 cm (d70) deep) were dug in the soil. the bed and walls of the trenches were covered with plastic and greased to prevent preferential flow from the plastic walls. then, the geocomposite layers were used as a drainage layer with a length of 4 m and a width of 20 cm. next, , soil was poured on the drain to a depth of 40 cm from the ground surface, according to the experimental setup (35 and 70 cm thick). to conduct the research, geocomposite sheets were used for both water influx layer and drainage layer. the treatments included two distances of 35 cm and 75 cm between the water influx and the drainage layer. in both treatments, the water influx layer was placed 40 cm below the ground surface. wastewater was injected 12 times at weekly intervals. at the beginning and end of the study period, soil samples were taken from two depths (0-40 cm and 40-80 cm), and ph, electrical conductivity total calcium and magnesium, carbonate and bicarbonate, nitrate, and fecal and total coliform levels were measured.results and discussionthe results showed an increase in electrical conductivity, nitrate, carbonate, and bicarbonate levels, total coliform, and fecal coliform in the soil at the end of the study period compared to the beginning of the study period. the ph of the soil decreased in both the upper and lower areas of the water table. th decrease in soil ph under wastewater irragation conditions is likely due to the nitrification of ammonium and the leaching of cations from the soil. however, the results of the anova of the effect of measurement depth, drain depth, and their interaction on soil ph changes showed that the effect was not significant. the electrical conductivity of the soil increased in both areas above and below the water table for both treatments. the results of anova of the effect of measurement depth, drain installation depth, and their interaction on percentage changes in soil electrical conductivity showed that the effect was not significant. the total calcium and magnesium content in the soil decreased by an average of 6.66 and 8.48% in d70 and d35 compared to the beginning of the period, but this difference was not significant. according to the results, the amount of soil nitrate increased as a result of irrigation with wastewater at both depths compared to the beginning of the research period. the concentration of total coliform and fecal coliform in the soil at the end of the period was higher compared to its initial value at the beginning of the period.conclusionthe green spaces on university campuses are major consumers of water. one potential water source for maintaining green space in the conditions of water shortage is the wastewater from the dormitories. however, the main problem with this water source is that during the periods of peak green space demand, the effluent from sewage is significantly reduced. the presence of organic matter, nutrients, and fecal matter in the sewage effluent simulates the activity, survival, and growth of bacteria, which was identified as a key factor contributing to soil coliform contamination. the initial microbial contamination in the soil wastewater application may be due to the use of animal manure containing pathogenic bacteria. in conclusion, the use of geocomposite sheets for land treatment during the period of the study did not have a negative effect on the chemical and biochemical properties of the soil, and this method can be used without significant concerns regarding soil contamination. however, other physical, chemical, and biological characteristics of the soil should be further investigated, and a final recommendation should be made regarding the use of wastewater.