Rotifers are microscopic aquatic animals of phylum Rotifera, live in a diverse range of aquatic habitats. They are important in ecology of freshwater ecosystems by recycling nutrients and can alter trophic dynamic of planktonic communities. These features have also been used to infer environmental conditions in an aquatic habitat. Because of the important roles of this group of animals in the trophic chains of aquatic environments and the need for discovering their biodiversity, this study was planned to analyze the patterns of rotifer community structure in response to temporal fluctuations in environmental variables in two water bodies in northwest Iran. Samples were collected seasonally between October 2014 and November 2015. Temperature, pH, DO, conductivity, salinity and rotifer abundance were measured. In total, 28 rotifer species belong to 10 families of phylum Rotifera were identified. Canonical correspondence analysis (CCA) was used to estimate the relationship between environmental variables and biodiversity of rotifer taxa. The clusters showed strong correlation with dissolved oxygen and electrical conductivity for shaping the rotifer assemblages in both reservoirs.

Rotifers are microscopic aquatic animals of phylum Rotifera, which live in a diverse range of aquatic habitats. They are important in ecology of freshwater ecosystems by recycling nutrients and can alter trophic dynamic of planktonic communities. These features have also been used as indicators of the environmental conditions in aquatic habitats. Considering the important roles of this group of animals in the trophic chains of aquatic environments and the need to explore their biodiversity, this study was planned with the aim of analyzing patterns of rotifer community structure in Kani-Brazan and Bohlul-Kendi water bodies located in northwest Iran. Samples were collected seasonally between October 2007 and November 2008. Temperature, pH, DO, conductivity, salinity and rotifer abundance were measured. In total, 28 rotifer species were identified from the two studied sites. In each site, rotifer species diversity differed seasonally. Canonical correspondence analysis (CCA) was used to estimate the relationship between environmental variables and abundance of rotifer taxa. The clusters showed strong correlation with dissolved oxygen and electrical conductivity for shaping the rotifer assemblages in both Kani-Brazan and Bohlul-Kendi reservoirs.

In this experiment, soil nutrients, amount of autumn litterfall and nutrients recycling via litterfall into forest floor and their relationships to each other were studied in three stands (Elm, Maple and Ash) at Darabkola Experimental Forest of Sari Agricultural Sciences and Natural Resources University (North of I.R. Iran). Soil samples were made from 0-15 cm depth of soil surface and their chemical properties (pH, EC and the concentrations of N, P, K, Ca and Mg) were tested. Three litter traps (50×50 cm) were randomly placed in each stand and litter was collected at monthly intervals in autumn. Because leaves usually form a significant percentage of litterfall amount, they were collected from each litter-trap at different months of autumn, dried and sieved and finally analyzed. Results showed that there was significant difference (p<0.05) between the tree species in terms of soil nutrient concentration,except P and K contents). The lowest amount of soil N, P, K, Ca and Mg belonged to Ash plantation. Overall, the greatest and the lowest amount of litterfall belonged to Maple and Ash species, respectively. The results showed that the stands were able to change th soil properties to some extent. It might be concluded that these changes are consistent with the differences observed in respect to the recycled nutrients at each stand.

The use of olive mill solid waste to form of compost in olive groves, in addition to helping dispose of this by-product of the olive oil industry, also can recycles nutrients that out of the garden during the fruit harvest. The aim of this study, was to riplacing of this compost with manure of animal at the olive groves as an organic fertilizer, improvement on the nutritional status of olive trees, fruit quality, fruit yield and oil.
Olive mill waste solid was mixed with 10% wheat straw (W/W) and two percent urea. The composting process was completed after three months. 12, 24 and 36 kg olive pumice compost was given per tree. Control trees donʹt received compost (first control) or 15 kg of manure (second control) instead of compost. The fruit yield, oil yield, fruit quality characteristics and leaf mineral elements content of ‘Zard’ and ‘Roughany’ olive cultivars were evaluated in compost treated and control over two years.
The most both fruit and oil yield in the first and second year after treatment belonged to the 12 and 36 kg compost treatment in ‘Zard’ cultivar that in the second year, fruit and oil yield was respectively 58 and 57 percent more than the first control in the same cultivar. In the first year, the highest oil percentage in the dry matter, belongs to the second control in the ‘Roughany’ cultivar. While, two years after treatment, the trees that treated with 24 and 36 kg of compost in the ‘Roughany’ cultivar had about 10 percentage of oil in dry matter more the trees that treated with manure in the same cultivar. Fruit weight, pit weight and fruit pulp percentage in ‘Zard’ cultivar was higher than ‘Roughany’ cultivar over two years. In the second year after treatment, the trees that treated with 36 kg of compost in ‘Zard’ cultivar had the highest fruit weigh and also pulp weight and pulp to pit ratio was more than the manur treatment in the same cultivar.
The highest nitrogen, in the first year after the treatment blonged to ‘Roughany’ cultivar, with 24 kg compost, that was more 26 percent than the first control in the same cultivar. In the second year after treatment blonged to ‘Roughany’ cultivar, with 24 kg compost, that was more 26 percent than the first control in the same cultivar. Two years after treatment, the trees were treated with 36 kg of compost had 10 percent more phosphorus than the first control. Also in this year, the ‘Zard’ cultivar had nine percent more potassium than the ‘Roughany’ cultivar. In the first year, ‘Zard’ cultivar had more calcium and magnesium, and less phosphorus and sodium than the ‘Roughany’ cultivar, respectively. In the second year after treatment, calcium and magnesium in the trees that treated with 24 and 36 kg compost was at the highest level statistically. The ratio of sodium to potassium in the first and second year, in the ‘Zard’ cultivar was less than’Roughany’ cultivar.
It seem olive trees that fertilized with olive mill pomace compost especially with 36 kg could improve nutrition status of olive tree such as leaf N, P, Ca and Mg in leaves and consequently improves fruit and oil yield and fruit quality especially in ‘Zard’ cultivar.

Proper management of sewage is one of the most important environmental issues, organic matter and nutrients, including phosphorus compounds, are the potential pollutants of the receiving waters. Release of phosphorus from municipal wastewater treatment plant effluent to the environment is one of the main reasons for the phenomenon of the Eutrophication. Therefore, the aim of this study was to determine the amount of nutrients and organic matter in wastewater of Yasouj city and efficient removal of nutrients such as total phosphorus by modified Bardenpho system.
This is a cross-sectional study. The sampling method as Composite Sampling and study population was samples of treatment system input (after screening system) and output of treatment system (after sedimentation). In order to identify of affecting factors on phosphorus removal use of modified Bardenpho pilot. The amount of nitrate, total phosphate, COD and BOD5 removal for 9 months was evaluated. The collected data were analyzed by using SPSS software (version 16).
Findings: According to the results, the average of input COD in system (674.55±228.54), input phosphorous (21.26±4.8), input nitrate (25.91±19.63), input BOD (378/33±106/66) mg per liter and the input pH (7.22±0.35). There is a significant Relationship between the input COD and percentage of phosphorus removal (P.value=0/004), but there is not significant relationship between the pH input and phosphorus removal percentage (P.value=0.339). Most phosphorus removal was observed in Solids Retention Time (SRT) of 15 days (69.72%). Internal recycle of 200 percent (68/96%) showed the highest percentage of phosphorous removal.
Discussion and According to obtained information, the optimum conditions for phosphorus removal showed SRT =15, HRT =0/5-1 in anaerobic tank, the internal recycle percentage of 200%, recycled activated sludge (75%) and keep the DO =2-3. Therefore, for removal of phosphorus addition of physical and chemical methods can use of modified biological processes. In this systems, by replacing of an anaerobic stage at the beginning of the process, improve phosphorus removal. This method can be a good alternative to treatment plants with activated sludge system.

Recycling of brackets can significantly reduce the price of fixed orthodontic appliances but if the bond is more prone to failure during treatment, this potential benefit will disappear. The aim of this study was to investigate the effect of chemical recycling on bond strength of metal orthodontic brackets and failure pattern of recycled brackets. In this experimental study Instron machine was used to measure shear bond strength (SBS) of brackets in two stages on 60 human maxillary first premolars using No-Mix composite. Shear bond strength and pattern of failure were compared between recycled and new brackets in two stages. Data were analyzed by ANOVA and Duncan tests. Adhesive Remnant Index was evaluated in different groups by Pearson Chi-square test. P<0.05 was considered as the limit of significance. Statistical analysis showed that the mean values of SBS for new bracket group was 12.00 MPa and for recycled group and double recycled group, 9.94Mpa and 10.00 MPa respectively. A significant reduction (about 18%) in bond strengths of brackets was observed at the first time of recycling. Recycling at the second time had no significant influence on the bond strength. Pattern of bond failure of these brackets showed that a great amount of residual adhesive material was remained on the teeth surfaces after debonding of recycled brackets which indicates that cleaning the teeth surfaces after debonding of recycled brackets is more time consuming. Based on the results of this study, before using recycled brackets, several advantages and disadvantages must be considered.

Using cover crops in conservation tillage systems offers many advantages, one of which is weed control through physical and chemical interferences. Most of the benefits of cover crops are well known. They prevent form wind and water erosions, conserve soil moisture by reducing evaporation and increasing infiltration, increase the content of organic matter, increase fertility by recycling nutrients, add nitrogen if they are legumes, and improve soil structure. Proper cover crops can also suppress weed growth by allelopathic activities and light interference. They impact on environmental quality through the protection of surface water and groundwater, as well as eliminating the need for using preemergence herbicides. Either increase or decreases have been reported for crop yields when the crop residues remain on soil surface. No-till system has been reported to increase the presence of certain difficult to control weeds. Therefore, the aim of this study was to investigate the effect of tillage systems and cover crops on weed control and corn yield.
Experiment was carried out as split plot based on randomized complete block design with three replications at the Bu-Ali Sina University in growing season of 2011. Tillage with moldboard, tillage with chisel (minimum tillage), and no tillage were considered as main plots and two cover crops, winter vetch and chicklingpea, chemical weed control and weed-infest treatment (control) were considered as sub-plots. Cover crops were cultivated in late March 2011. In early June 2011, cover crops were harvested and were spread over the soil surface. The Plot size was 22.50 m-2. Five rows were in each plot with 75 cm intervals among rows and 18 cm among seedlings. 2 square were picked in the three central rows of each plot in order to determine the yield and yield components. From each plot three quadrants (1×1 m)randomly were picked and weeds and cover crops was separated. All samples were dried at 72 ° C for 48 hours and then were weighed. Data were analyzed using SAS software. Wherever the F test showed significant effect for a source of variance, the differences among treatments were compared by LSD test at the 0.05 level of significance.
Analysis of variance showed that the effects of tillage systems and weed control methods were significant on all traits, except number of seed per ear. Also, the interaction effect of them had significant effect on number of grain row/ear and grain yield. The highest grain yield (1271 g m-2) was observed at combined treatment of winter vetch cover crop and moldboard tillage. This treatment had no significant difference with combined treatments of cover crops and tillage with chisel. In comparison with winter vetch cover crop and conventional tillage treatment, the lowest grain yield by 45% reduction was recorded at weed infested and no tillage treatment. Also, the effects of tillage systems and weed control methods and their interaction were significant on weed density and biomass. Maximum weed density and biomass (60 plant m-2 and 335 g m-2) were belonged to weed-infested treatment under no tillage system. The lowest values for weed density and biomass with reduction of 62 and 53%, respectively, were observed at combined treatment of chicklingpea cover crop and minimum tillage. Chicklingpea and winter vetch cover crops due to rapid establishment and growth capacity are more suitable for weed control. Cover crops can affect weed establishment through effects on the radiation and chemical environment of weed and inhibit weed emergence by physically impeding the progress of seedlings from accessing light as well as by releasing phytotoxins that inhibit seedling growth. Minimum tillage is often cause changes in of weed flora and their population, and this is one of the methods for integrated weed management. In general, using winter vetch and chicklingpea as a cover crop and tillage with chisel suppressed about 50-60% weeds and increase corn yield which is effective step towards achieving sustainable agriculture.

Municipal effluents can often contain significant concentrations of organic and inorganic nutrients. There is potential for these nutrients to be used as a fertilizer source when the water is recycled as an irrigation source. Therefore, long-term irrigation with municipal effluents can add large amounts of nutrients to the soil and plant. A case study was undertaken to assess the impact of municipal effluent irrigation on macro and micro-nutrient (N, P, K, Ca, Mg, Fe, Mn, Cu, Zn) concentration of soil and leaf of eldar pine (Pinus eldarica Medw.) trees, in south of Tehran.
For this purpose, Data were collected using technique of systematic random sampling with 4 replicates in two 15 year-old-artificial eldar pine stands 1) under irrigation of municipal effluent and 2) irrigated with well water. Municipal sewage and well water were sampled daily (3 days in each month) from early June to late November.
Results indicated that the concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) in municipal effluent and leaf of trees irrigated with municipal effluent were significantly greater compared with those of well water treatment. Application of municipal effluent resulted in a 1.5-fold increase in the concentrations of soil macro and micro-nutrients. The nutrients showed their greatest values in the upper layer of soil (0-15 cm). Irrigation using municipal effluent did not result in toxicity of nutrients in tree leaf and soil. The macro and micro-nutrient contents of leaf were correlated with their respective value in soil.
It might be concluded that the municipal effluents could be utilized as a source of water and nutrients in afforestations.

Olive (Olea europaea L.) trees are mainly cultivated in the Mediterranean area and are grown for their oil or processed as table olives. Despite the fact that olive is known to be resistant to drought conditions due to its anatomical, physiological, and biochemical adaptations to drought stress, reports indicate that the olive can be adversely affected by drought stress, which has a negative effect on the growth of olive trees. In the absence of adequate supplies of water, the demand for water can be met by using improved irrigation methods or by using reclaimed water (RW). Reports have shown that recycled water has been used successfully for irrigating olive orchards with no negative effects on plant growth.Attention has been paid to reclaimed water as one of the most significant available water resources used in agriculture around large cities in arid and semi-arid regions. On the other hand, irrigation efficiency is low and does not meet the demands of farmers.In order to investigate the possibility of irrigating olive orchards with subsurface leakage irrigation (SLI) in application of reclaimed water, an experiment was carried out with the aim of investigating the effect of reclaimed water on photosynthetic indices and morphological properties of olive fruit. Research was conducted using a split-plot experimental design with two factors (irrigation system and water quality) on the campus of Isfahan University of Technology in Isfahan, Iran, on a sandy-clay soil with a pH of 7.5 and electrical conductivity (EC) of 2.48 dSm-1.PVC leaky tubes were used for the SLI system. The SLI system was installed 40 cm from the crown of each tree at a depth of 30 - 40 cm.At the end of the experiment fruit yield, weight per fruit, volume, length and firmness were calculated. A portable gas exchange system (Li-6400., LICOR, Lincoln, NE, USA) was used to measure the net rate photosynthesis (A), the internal partial pressure CO2 (Ci), and stomatal conductance (gs) between (09.30 – 11.30 h) on a fully expanded current season leaves situated at mid canopy height. Statistical assessments of differences between mean values were performed by the LSD test at P = 0.05. Results and Discussion The results revealed that reclaimed water enhanced fruit yield, weight (15%), volume (23%) and leaf photosynthesis (22%) in plants compared with clear water. Recycled water was found to supply more nutrients than clear water. High nutrient concentrations in RW, compared to those in clear water, result in nutrient accumulation in the soil, making them available to plant roots to promote overall plant growth and fruit production. Improved N, P, K nutrition of wastewater-irrigated plants has been reported (Farooq et al, 2006). Olive leaves and stems represent storage organs for N and release it in response to the metabolic demands of developing reproductive and vegetative organs (Fernandez-Escobar et al., 2004). However, Al-Abasi et al. (2009) found no statistical differences. Irrigation with SLI systems increased the photosynthesis (33%), and stomatal conductance (57%) when compared with surface irrigation systems. The results showed that reclaimed water had a significant effect on photosynthesis and stomatal conductance. However, fruit length and firmness had no significant difference. Substomatal CO2 decreased when the SI systems were used for irrigation. Also SLI system could enhance fruit yield (65%), weight (17%), photosynthesis (32%) and chlorophyll Fluorescence (Fv/Fm) (18%). The SLI systems with recycled water induced greater shoot growth, total leaf surface area, and transpiration during the entire growing period. This led to an overall positive effect on mean fruit weight and total fruit production per tree. The SLI system applying RW led to more photosynthesis by 34% as compared to the SI system. In the present study, the SLI system delivered water directly in the root zone and improved water availability, which enhanced photosynthetic assimilation rates and plant growth to a great extent. David et al. (2003) showed that subsurface drip irrigation versus other irrigation methods reduced evaporation and improved growth and production in peach trees. As a conclusion, the results from this research show that recycled water could be a promising resource for irrigation of olive trees and acted as a source of nutrients and irrigation water.In addition, SLI irrigation system is more efficient in irrigation of olive trees when compared to surface irrigation system and proved beneficial for olive growth.

Discharging wastewater effluent to surface water or groundwater is so dangerous for environment, while it includes nutrient. As the phosphorus and nitrogen combinations in the aquatic environments have harmful impacts (mainly the poisonousness of ammonia, overgrowth of aquatic plants, groundwater pollute to nitrate and diseases caused by drinking the polluted water, and also eutrophication, resulting in frequent outbreaks of algal blooms and threatening the reliable supply of drinking water resources), some limitations were imposed on the consistency of these combinations in the entry waste. So nowadays removal of these combinations must be considered in designing of the treatment plants and also systems designed for treating the municipal wastewater must be able to remove nitrogen and phosphorus combinations to reach the standard limit. Therefore, in order to good performance of the aerobic-anaerobic A2/O method, it is proposed in this research and a study in advanced treatment of municipal wastewater using the A2/O method to remove nitrogen and phosphorus in the pilot scale in Ekbatan WWTP has been done.
In this research, firstly the principals of biological removal of nitrogen and phosphorus, and secondly the basis of designing biological treatment plants have been investigated. Then for laboratorial studies, an A2/O pilot has been made. This pilot consists of anaerobic, anoxic and aeration tanks and also sedimentation tank. The volume of these 4 tanks are 40, 60, 170 and 120 L, respectively. In order to simulate the real condition, this pilot has been set up in Ekbatan plant and the experiments were done to observe the effect of hydraulic residence time on nitrate, ammonia and phosphorus removal and also the effect of oxic mixed liquor recycling ratio on nitrate removal has been conducted. In order to observe the nitrate, ammonia and phosphorus removal process efficiency, the experiments were done in a period of three months and in 5 aeration hydraulic residence times, 4, 6, 8, 10 and 12 hours. In these experiments, the returned sludge was 25% and the oxic mixed liquor recycling ratio was 75%. After determining the best hydraulic residence time, experiments continued in 5 different oxic mixed liquor recycling ratios, 75%,150%, 225%, 300% and 375%.
It was concluded that at aeration hydraulic residence time of 8 hours, 96% COD , 95% ammonia and 79% phosphorus (effluent: 9 mg/L COD, 0.87 mg/L ammonia, 2.1 mg/L phosphorus, 18.7 mg/L nitrate) removal were achieved and that was the best HRT. Furthermore, according to the mixed liquor recycling ratio experiments, when the oxic mixed liquor recycling ratio was about 180 - 200%, optimum removing nitrate has been occurred. Although the mixed liquor recycling ratio of 225 - 275% resulted better efficiency for nitrate removal, it is not proposed, because effluent limitations in Iran for the nitrate is up to 10 mg/l which it is resulted in the mixed liquor recycling ratio of 180 -200%, and the other reason is that, with increasing the oxic mixed liquor recycling ratio, energy costs will increase, too.