Evaluation of Softening of Clayey Soil Stabilized with Sewage Sludge Ash and Lime

Production of sewage sludge have raised increasing concerns due to negative environmental effect. Sewage Sludge Ash (SSA) is used as a new type of additive for clay. Laboratory tests were performed on clay samples to study the mechanism of sewage sludge ash (SSA) and Hydrated Lime (HL) soil stabilization. Different SSA contents (0, 5, 10, 15%) and hydrated lime (0, 1, 3 and 5%) were added to the soil samples. 288 samples were prepared, and unconfined compressive strength tests were carried out. The samples were tested under optimum water content and also saturated conditions with three replications. The results of the coefficient of softening indicated that by adding SSA and hydrated lime to clay soil simultaneously, the stabilized clay soils can be applied in the moist and saturated condition. According to the results, the samples of SSA contents 0% with hydrated lime 5% and SSA contents 10% with hydrated lime 5% can be placed in the vicinity of moisture

Hydrologic drought indices analysis by regionalization methods in southwest of Iran

11 p.International audienceDrought is a recurrent extreme climate event with tremendous hazard for every specter of natural environment and human lives. Drought analysis usually involves characterizing drought severity, duration and intensity. Usually, long-term datasets of hydrometric and hydrochemical information are needed to begin an evaluation of dominant low flow (as hydrologic drought indices) producing processes however, in many catchments, these data are not available. A major research challenge in ungauged basins is to quickly assess the dominant hydrological processes of watersheds. In this paper, for developing regional models, low flow analysis has been performed by 3 regression methods (multivariate regression, low flow index method, regionalization model of frequency formula parameters) and Hybrid low flow model in Karkheh basin (southwestern of Iran). Estimated error for four methods show although hybrid method can also use for low flow regionalization analysis but multivariate regression and low flow index methods are more suitable for this purpose

Effectiveness of Vetiver system in improving biological characteristics and electrical conductivity of wastewater

The increasing population and development of agricultural and industrial activities have put excessive pressure on freshwater resources. As a result, wastewater treatment has received growing attention in recent years. It seems more necessary in arid and semi-arid regions such as Iran, where we face climate change and a lack of rainfall (Mohammadi Moghadam et al., 2015; Nikmanesh et al., 2018). However, wastewater is one of the most critical environmental pollutants. If the microbial quality of the effluent and its hygienic aspects are not taken into account, its reuse poses a severe risk to human health and the environment (Abedi-Koupai et al., 2021). Therefore, the primary purpose of disinfection effluent from municipal wastewater treatment plants is to reduce the concentration of water-borne pathogens to less than the amount of infectious. Disinfection is done by physical and chemical methods. In most parts of the world, chlorine is the premier option for disinfecting effluents. That said, the adverse effects of chlorine effluent disinfection on humans and the environment have led to the possibility of using phytoremediation to improve the biological properties of water (Keddy, 2010). The Vetiver (VS) system for wastewater treatment is an innovative phytoremediation technology that has fantastic potential. This plant can grow in saline environments (Sanicola et al., 2019). Moreover, it can significantly improve the water quality parameters (Abedi-Koupai et al., 2021). Therefore, this study aims to investigate the possibility of using Vetiver in urban wastewater hydroponically to evaluate its efficiency in removing and refining pathogens, especially gastrointestinal coliforms. Our purpose is to use the treated water in the agriculture sector for irrigation

Quantification of Groundwater Recharge in the Karvan Aquifer in Isfahan (Iran) Using the CRD Model

Identification of the net groundwater recharge is essential for groundwater modeling and water resources management.  Due to its simplicity and its minimum stochastic parameter requirements, the CRD model has been widely applied to estimate recharge. Rainfall is the main source of groundwater recharge in the Karvan area in Isfahan(Iran). The area is located in the semi-arid zone and there is no source of recharge other than rainfall. Estimation of groundwater recharge from rainfall is not an easy task since it depends on many uncertain parameters. The cumulative rainfall departure (CRD) model was used in this study to estimate the net groundwater recharge from rainfall. The cumulative rainfall departure (CRD) model is based on the principle of water balance and does not require much data as is the case with other conventional methods of recharge estimation. The CRD model was conducted using the optimization method to minimize the root mean square error (RMSE) between the measured and the simulated groundwater head. The results indicated that the annual amount of groundwater recharge from rainfall in the Karvan Aquifer in Isfahanis about 48.07 million m3

Effect of Clinoptilolite Zeolite Application on Reducing Urea Leaching from Soil

Nutrients and insecticides in runoff or drainage water from the agricultural lands have of long posed a great challenge to surface and ground water quality. In agricultural production, fertilizers supply the main source of nitrogen required for plant growth. Investigations have shown that part of the nitrogen fertilizers are excluded from the root zone and leached into the groundwater or rivers. Modern technologies employed cultivation, irrigation, and fertigation management s well as changes in the structure of fertilizers and insecticides could have positive effects on reducing the leaching of nitrogen. The objective of this research was to study the effect of clinoptilolite zeolite application on reduing urea leaching from soil. In this greenhouse experiment, four levels of zeolite (0, 5, 10, and 15% added to a silty clay loam soil), one level of leaching (25% of net irrigation depth), one level of fertilizer application (60 mg/L), two sizes of Mianeh zeolite (50 and 200 mesh), and one size of Mashhad zeolite (200 mesh) were used in four irrigation events. The results showed positive effects of zeolite on reducing urea leaching. The nitrogen concentration in the 0% zeolite treatment was reduced from 1337 mg/L (after the first irrigation) to 16 mg/L (after the fourth irrigation event). But, for 15% Mianeh zeolite (50 mesh),   these values were 427 and 54 mg/L. Comparison of zeolite types showed that Mashhad zeolite was more effective in adsorbing urea than Mianeh zeolite (both 200 mesh). Zeolite, in addition to reducing the urea potential for groundwater pollution, was able to decrease the rate of solute transport. It was found that zeolite size can have significant effects on the leaching of contaminants. Finer zeolite particles absorb and hold more urea

Investigation the Kinetic Models of Biological Removal of Petroleum Contaminated Soil Around Oil Pipeline Using Ryegrass

The industrial revolution of the past century has resulted in significant damage to environmental resources such as air, water and soil. Petroleum contamination of soil is a serious problem throughout the oil producer countries. Remediation of petroleum contamination of soils is generally a slow and expensive process. Phytoremediation is a potentially less-damaging, cost-effective, but needs longer-term for remediation of contaminated land compared to the alternative methods. In this study the kinetics of petroleum hydrocarbon contaminated soils in Khozestan were investigated. For this paper Ryegrass (Lolium perenne) plant selected and the decline of total petroleum hydrocarbon (TPH) was analyzed after growth stage, every 10 days up to 90 days. The results of TPH concentration was fitted with zero-order kinetic, first-order kinetic and Higuchi model. The result indicated that degradation of TPH with presence of plants as a function of time was well fitted with the first-order kinetic model. The first-order rate constants (K) and half-lives (T1/2) for TPH degradation were 0.0098 1/day and 71 day; respectively. The results of phytoremediation showed that there were 65% decreases in TPH concentration with Ryegrass during the 17 weeks