تصفيه نيترات زهاب هاي كشاورزي با استفاده از بيوراكتور

Nitrate treatment of agricultural drainwater using bioreactor

با افزايش روز افزون جمعيت نياز به توليد محصولات كشاورزي و غذا افزايش پيدا كرده است. استفاده كشاورزان از كود‌هاي شيميايي باعث آلودگي منابع آب و خاك مي‌شود. از پركاربردترين كود‌ها، كود نيتراته (اوره) است كه آبشويي آن از طريق زهاب‌هاي كشاورزي مشكلات زيادي را براي محيط زيست به دنبال دارند. امروزه يكي از روش‌هايي كه در علم زهكشي در كنار زهكشي كنترل شده براي حذف نيترات مورد توجه قرار گرفته است استفاده از بيوراكتور‌ها است. در اين مطالعه از كاه و‌كلش گندم به عنوان بستر و محيط بيوراكتور براي تصفيه نيترات مورد استفاده قرار گرفت. پژوهش مورد نظر در 51 روز در سه تكرار و در چهار مرحله تزريق با زهابي با غلظت حدود 54 ميلي‌گرم برليتر براي نيترات انجام شد. تمام اندازه‌گيري‌ها در محل آزمايش با دستگاه فتومتر مدل 7100 انجام شد. نتايج اين پژوهش نشان داد كه غلظت نيترات با گذشت زمان بين 6 تا 24 ساعت پس از تزريق زهاب بين 54 تا 100 درصد كاهش مي‌يابد؛ كه بيانگر عملكرد قابل قبول اين بيوراكتور بوده است. همچنين نتايج حاصل از آزمون‌هاي آماري نشان داد كه با گذشت 51 روز از زمان ماند كاه‌وكلش گندم هيچ تفاوتي در ميزان كاهش غلظت نيترات (عملكرد بيوراكتور) ايجاد نشده است. همچنين نتايج نشان داد در طول آزمايش، دما اثر معني-داري بر كاهش غلظت نيترات نداشته است اما دماي بالاتر از 29 درجه سانتي‌گراد سرعت تصفيه نيترات را كاهش مي‌دهد. با توجه به نتايج حاصل مي‌توان از بيوراكتور‌ ها با بستر كاه و كلش گندم به منظور كاهش غلظت نيترات زهاب‌هاي خروجي در پايين دست مزارع استفاده نمود.

With increasing population growth, the need for food has increased, resulting in increased agricultural production needs. To produce more, there are three important sources of soil, water and fertilizer, the unskilled use of chemical fertilizers by farmers leads to damage to the soil and to water and, consequently, to human health. Over the last few decades, attention has grown to the environment, and hence the preservation of natural resources, including water and land, has become more important. Of the most widely used fertilizers, nitrate fertilizers (urea) and phosphate fertilizers are introduced into the environment after the use of additional amounts through agricultural drainage, which has led to phenomena such as nutrition, as well as dangerous diseases such as cancer. Filtration of these elements requires high costs. But a new method in drainage science is being studied and studied, which, along with controlled drainage, can solve many of these problems. This method uses bioreactors that have a natural background and can provide a good environment for the activity of the biologists. Regarding the costs and availability of wheat in all parts of Iran, wheat straw were selected as a bioreactor bed. The research was carried out in 24 hours with three replications of this experiment with a wastewater with about 54 mg/L nitrate. All measurements were carried out on the test site with a 7100 photometer. The results of this study showed that nitrate concentration decreases over time. The results of this study showed that the decrease in nitrate concentration increased over time. Minimum reduction rate of nitrate was 54% and the maximum reduction was 100%, which showed acceptable performance of the bioreactor. Also, the results of statistical tests such as t and analysis of variance showed that 51 days of wheat straw had no difference in the reduction of nitrate concentration (bioreactor yield). There was a significant effect of temperature and initial concentration on the results. In the first step, the initial concentration was ineffective in this study and the covariance test was performed to examine the effect of temperature on the longevity of straw and straw that showed a lack of temperature effect. According to the results, we can use the bioreactor with wheat straw to reduce nitrate concentration of drain water in downstream fields.