JWSS - Journal of Water and Soil Science

Constructed wetland as a purification system plays an important role in water and wastewater treatment and so many research studies have been conducted to examine their efficiency for wastewater treatment. The aim of this study was to evaluate the efficiency of constructed wetland for Arak wastewater treatment plant. In this research, the efficiency of three horizontal subsurface constructed wetlands built with 3*12 meters in dimensions and 1 meter in depth was examined. In these constructed wetlands, two plants including Common reed (Phragmites australis) and Cattails (Typha latifolia) were planted and one unit was left unplanted. TSS, COD, BOD and TC parameters were measured in the 2 week samples and the results were analyzed by SPSS and Excel. The results showed that the type of vegetation had no significant influence on the organic matter removal in the subsurface constructed wetlands; however, the removal efficiencies in the planted constructed wetlands were more than those in the unplanted control one. The TSS, COD, BOD, FC and TC removal efficiency in the constructed wetlands changes was 79%, 60.7%, 45.6%, 86.1% and 90.1%, respectively, for Common reed wetland and 77%, 61.4%, 59.8%, 92.4% and 93.1%, respectively, for Cattails wetland; thee were 69%, 44.5%, 43%, 83.6% and 88.8% for the  unplanted wetland, respectively. The results of this research also showed that the organic matter removal was dependent on the influent organics nature and biodegradability. The organic concentration in the wetland effluents met the Iranian regulation limits for different reuse applications, showing the constructed wetland could be a suitable technology for wastewater treatment in Iran.

The goal of this study was to investigate the effects of treated urban wastewater and different harvesting times on the yield and yield components of Sorghum (cv. Speed feed) in the greenhouse condition. The research was done based on a completely randomized design including 3 replications as pot planting in Ferdowsi university of Mashhad in 2016. In this study, the effects of four mixtures consisting of the moderations use of the treated urban wastewater and freshwater (0, 25, 75 and 100 percent mixture of treated urban wastewater and freshwater) and three harvesting times level (pre-flowering, after 50 percent of the plant to flowering, and grain filling stage) on the yield and yield components of Sorghum were evaluated. The results inducted that the effect of different moderations of irrigation regimes on all of them parameter was highly significant (P<0.01), but plant height was non-significant; it was also revealed that the effect of harvesting times on all of the parameters was highly significant (P<0.01), but leaf width was non-significant. The results also exhibited that the interaction effects of irrigated regimes and harvesting times on the leaf number, panicle length and width, leaf, panicle, and stem was highly significant (P<0.01), but plant height, stem diameter, branches number, and leaf length and width were significant at the  5 percent level (P<0.05). Also, the use of 25, 75, and 100 percent mixture of wastewater resulted in the  forage yield of  37.5, -29.3, and 12.9 percent (pre-flowering); -31, -15.3, and -47.4 percent (after 50 percent of the plant to flowering),  and -11.8, -35.7 and -28.4 percent (grain filling stage), respectively. The highest forage weights (46.2 g per plant) showed, in the study, irrigated by a mixture of 75 treated wastewater and 25 freshwater, and harvesting the plant after 50 percent in flowering stage; on the other hand, the best treatment in this study irrigation by the mixture of 75 treated wastewater and 25 freshwater and harvesting the plant after 50 percent in the flowering stage, Thus, using the treatment in farm experiment required the field research.

One of the ways to reduce the amount of wastewater pollution is the use of constructed wetlands. In this research, the performance of a hybrid constructed wetland with pumice ore and vetiver plant on urban wastewater has been investigated. Hybrid wetlands with these specifications were constructed in the vicinity of wastewater treatment at the Isfahan University of Technology. To evaluate the performance of constructed wetland the effects of three and six days of retention time on the removal efficiency were studied using a completely randomized design. On average, for three days of retention time, in the wetland with the vertical flow, the horizontal flow, and hybrid wetland, fecal coliform was 47.4, 98.3, and 99.1 percent, BOD₅ was 7.6, 20.9, and 26.9 percent, and the COD was 4.6, 40.0, and 42.7 percent decreased, respectively. Also, during the six days of retention time in the wetland with the vertical flow, the horizontal flow, and hybrid wetland, fecal coliform was 61.6, 99.3, and 99.8 percent, BOD₅ was 10.7, 29.9, and 37.4 percent, and COD was 16.0, 86.8, and 88.9 percent decreased, respectively. The combination of Pumice as a porous material with the ability to absorb the elements as well as vetiver as a plant capable of phytoremediation indicated a very suitable performance during low retention time.

The growing concern for environmental protection and increasing demand for green approaches to address environmental problems have prompted researchers to explore a sustainable and reliable method for treating dyeing wastewater. One of the sustainable and reliable methods is the electrocoagulation process. In this study, a batch electrocoagulation reactor was designed to evaluate the efficiency of this process in treating dyeing wastewater. The effects of two parameters, electrode distance and retention time, on pollutant removal efficiency were investigated. Electrode distances of 2, 5, and 7 cm were tested, and retention times of 10, 15, 20, 25, and 30 minutes were examined. Results indicated that the optimal electrode distance was 5 cm and the optimal retention time was 20 minutes. Under these conditions, the removal efficiency of BOD, COD, TSS, color, and turbidity reached 83%, 85%, 98%, 98%, and 93%, respectively. The results of this research demonstrate the significant potential of the electrocoagulation system for treating dyeing wastewater.