نشریه علوم و مهندسی آب و فاضلاب
سال سوم شماره 3 (پاییز 1397)

The growing use of medicines and the unknown and known consequences of drugs in the environment have intensified concerns about the infiltration of these complex compounds into the aquatic environments. The concerns include concentration of such compounds in the food chain and the endocrine glands, drug resistance and impact on the fertility of wildlife. From the medicines used, 5 to 90% are discharged as glucoronides through urine or feces after losing their toxicity in liver. On a global scale, the medicines that control blood cholesterol, the heart and coronary drugs, and the anti-depressants are the medicines most widely used. These have also been identified in water resources and even in drinking water. WHO has confirmed the existence of 15 to 25 widely used drug residues in drinking water at the scales of nano and micro gram per liter. In Iran the Codeine Acetaminophen, Cold medicine and Amoxicillin are in the first three ranks followed by Diphenoxylate capsules and Dexametasone injections, which jointly occupy the fourth place. To tackle the undesirable consequences and concerns about the presence of medicines in water, training programs aiming at reducing consumption and proper use of drugs and hygienic products and cosmetics, setting regulations and guidelines for appropriate discharge of unused or partially used drugs and implementing adequate monitoring and punitive and motivational measures have been emphasized. For the removal of the remaining hormones, drugs, and antibiotics, redesigning the filters and using chlorine and ozone oxidants, membrane processes such as reverse osmosis, nano filtration, ultrafiltration, and microfiltration with simultaneous radiation of ultraviolet and a minimum particle size of 400 mJ/cm2 and injection of at least 3 mg per liter of peroxide Hydrogen has been tested.

The aim of this study is to reduce p-nitrophenol from wastewater using an SBR reactor for biological treatment of sewage and to study the effect of concentration of p-nitrophenol in wastewater on reduction of biomass production and sludge volume index. For this study, two SBR reactors with a volume of 20 liters with on-line control system were used. Once the stable conditions in the reactors are met, sampling and testing of parameters such as COD, MLSS, MLVSS, PH, DO, SV1, SOUR, and p-nitotrophenol (PNP), as well as the rate of reduction in production of biological solids were performed during the 12 months of research. The results showed that for the inserted amount of more than 100 mg/l of PNP, the COD decreased from 772 to 193 mg/l while the COD removal efficiency decreased to 75% and the PNP concentration decreased to 36.7 mg/l. The biodegradable solids decreased by about 49.5% relative to the control reactor. On the other hand, in this dose of PNP, the amount of SOUR was 31 mg O2/h, and VSS and the SVI value was less than 48 ml/g.  For the PNP dose of 150 mg/l, no biosolids was produced in the reactor but COD and PNP levels increased in the effluent. The presence of toxic organic compounds such as p-nitrophenol in high concentrations in the wastewater while reducing the removal efficiency of the organic matter decreases the biological solids and thus reduces the amount of excess sludge.

Due to the limited resources of the water and the excessive growth of the population, the use of sewage in agriculture and green space irrigation is inevitable. In this regard, a research was carried out in city of Yazd to investigate the effect of irrigation with refined and untreated sewage on Rosmarinus officinalis, a species in the urban green space. This study was carried out in a randomized complete block design with five treatments (drinking water, refined wastewater, non-refined wastewater, refined wastewater + drinking water with a ratio of 1:1 and non-refined wastewater + drinking water with a ratio of 1:1) and 5 replicates. The results of chemical characterization of irrigation treatments showed that pH (7.2) and EC (1.27 ds/m) and the concentration of heavy metals, Pb and Zn in the effluent were in accordance with the FAO standard (0.5 and 0.24 mg/l, respectively) but cadmium concentration in both treatments was higher than the FAO standard level (0.02 and 0.04 mg/l). The results of morphological traits of Rosmarinus officinalis showed that there was no significant difference between different concentrations of sewage in terms of plant growth and root dry weight (p >0.05). The effect of irrigation with wastewater on dry weight of shoot and plant diameter was statistically significant (p <0.05). The highest dry weight and diameter were obtained with non-refined wastewater. The results of physiological traits such as chlorophyll a, chlorophyll b, total chlorophyll, glucose and proline showed a significant difference between treatments (p <0.05). The highest amounts of chlorophyll a, chlorophyll b, and total chlorophyll were observed for the irrigation with refined wastewater, and the highest amount of glucose and proline was related to irrigation with non-refined wastewater.

The history of water supply in the Yazd desert province indicates many difficulties experienced by the people of this province throughout the years. The predecessors living in Yazd province provided water for agricultural and drinking purposes to citizens by creation of traditional structures and through the management of seasonal river waters, springs, groundwater and harvesting water from atmospheric precipitation. With the establishment of a modern water supply system, the historical water structures which were forming the water supply process in the province were abandoned from the operation. However a significant proportion of these structures are still operational. Accordingly this study is addressing the weaknesses caused by modern water supply systems and the necessity to use traditional water supply as well as other proposed solutions (including the creation and strengthening of new urban settlements, the development of optimal methods for production and utilization of water resources, develop optimal methods of water consumption, etc.). The study is based on descriptive-analytic method and used field observations and interviews conducted by native experts of Yazd province. According to the research, the use of capacities of traditional structures in the province is one of the practical and operational solutions that can be used for passive defense regulations of water supply system in Yazd province. The results of this paper considers the use of the traditional water supply system and its integration with modern urban water supply as a must in accordance with the principles of passive defense and as one of the strategies for proper management of drinking water in Yazd city.  Of course, to achieve sustainability in providing drinking water to this city, it is necessary that other proposals in this article be taken into consideration by the respectable authorities of the province.

According to the severe shortage of water resources in Iran, water resources forecast is one of the most important issues in the national policies. The purpose of this study was to evaluate the efficiency of the Singular Spectrum Analysis model in forecasting the amount of groundwater resources in Iran versus ARIMA model. Singular spectrum analysis is a method which is suitable for analysis of nonlinear and stationary time series. For this purpose, water resources time series from 1983 to 2015 were used annually and the short-term and medium-term forecasts obtained from the two models were compared. According to the results, the SSA method was able to perform better in short and medium term predictions compared to the ARIMA model. Correspondingly the results showed 70% improvement in prediction of one step ahead up to 88% improvement in prediction of 3 steps ahead.

High TDS and TSS in water is usually important causes of clogging emitters. Irrigation with high EC and TDS has an adverse effect on drip irrigation. In this study, the effect of Conocarpus on removal of dissolved solids from aqueous solution was investigated. Batch tests were conducted to verify the removal of dissolved solids from the aqueous solution and the efficiency of the sorbent was determined. Various parameters such as pH, contact time and initial concentration of adsorbent was tested on the absorption of dissolved solids. The optimum pH for both absorbents were 3 and for absorbent straw the equilibrium time of 10 minutes was obtained. Adsorption efficiency for 0.1 g of adsorbent was recorded as %93.55, respectively.  With increasing the concentration of dissolved solids (83-960 mg/l), the efficiency of adsorption for straw was decreased from 88.9 percent to 42.5 percent. Between the isotherms which were studied, the adsorption process followed the Langmuir isotherm model. Among the kinetic models Lagergren kinetics model had a better match to the experimental data.