Chlorine as an integrated approach for environmental health and hygiene:A case study on evaluation of the performance of waste stabilization ponds located at 11 governorates in Egypt

The current study summarizes the current status of wastewater stabilization ponds(WSPs)treatment plants that have already been built in 11 governorates throughout Egypt.Moreover,this study aims to determine the most appropriate chlorine dose for waste stabilization ponds(WSPs)effluents to ensure the treated effluents are suitable for reuse in unrestricted irrigation and to comply with the current legislation on direct discharge onto water bodies.According to the findings,the chlorine doses used as a disinfectant in the treated effluents of the majority of WSP treatment plants ranged from 3 to 13 mg/L.Meanwhile,two of the WSPs treatment plants effluents,the Qus WSPs treatment plant in Qena governorate and the Al Zarabii WSPs treatment plant in Asyut governorate used high chlorine doses reached to 17 and 19 mg/L,respectively.This is due to the fact that both the Qus and Al Zarabii WSPs treatment plants have a high organic load,which necessitated the use of more chlorine to achieve the optimum chlorine dose at 13 mg/L for Qus and 11mg/L for Al Zarabii.The findings demonstrated that chlorine has a powerful effect in completely removing bacteria.Furthermore,in most chlorine-treated wastewater final effluents,as the chlorine doses increased,the chlorophyll-a reading decreased.The amount of trihalomethanes(THMs)produced as disinfectant byproduct was measured.The results proved that the water can be used in unrestricted irrigation,and after adding chlorine,it can be dumped on water bodies without health risks.

Safety assessment of waste rock dump built on existing tailings ponds

The construction of waste rock dumps on existing tailing ponds has been put into practice in China to save precious land resources. This work focuses on the safety assessment of the Daheishan molybdenum mine waste rock dump under construction on two adjoining tailings ponds. The consolidation of the tailings foundation and the filling quality of the waste rock are investigated by the transient electromagnetic method through detecting water-rich areas and loose packing areas, from which, the depth of phreatic line is also estimated. With such information and the material parameters, the numerical method based on shear strength reduction is applied to analyzing the overall stability of the waste rock dump and the tailings ponds over a number of typical cross sections under both current and designed conditions, where the complex geological profiles exposed by site investigation are considered. Through numerical experiments, the influence of soft lenses in the tailings and possible loose packing areas in the waste rock is examined. Although large displacements may develop due to the soft tailings foundation, the results show that the waste rock dump satisfies the safety requirements under both present and designed conditions.

Low-Cost Technologies for Mining Wastewater Treatment

The mining industry has contributed tremendously to the global economy.However,waste generated by this activity poses many challenges.Current low-cost technologies for the removal of heavy metals from mining wastewater include biosorption,adsorption,CWs(Constructed Wetlands)and waste stabilization ponds.This chapter focuses on sustainable mining wastewater treatment technologies with emphasis on gold mining wastewater.It discusses the technical and environmental challenges associated with mining effluent treatment,process conditions for optimum plant performance,efficiency,limitations and the economics of treating mining wastewater.The overall treatment cost of metal contaminated wastewater depends on the process employed and the local conditions.In general,technical applicability,cost-effectiveness and plant simplicity are the key factors in selecting the most suitable treatment method.Proper management of the spent biosorbent and solid wastes generated is also discussed.

Preliminary Calculation of a Natural System Based Treatment Plant for Grey Water from Butare Central Prison, Rwanda

After the chemical and biological analyses of grey water from Butare Central Prison in Butare city, District of Huye, southern province of Rwanda, the resulting data were used in preliminary calculations of a natural system based treatment facility. In our region, natural systems, lagoons and constructed wetlands were identified as potential effective technologies for wastewater treatment due to the low cost and favorable climate. In our study, the authors calculated two systems of treatment plants, one based on two ponds associated with a constructed wetland and another based on three ponds. This study aims at raising awareness of the required land surface that can allow the use of extensive technologies in treating domestic wastewater from the prison. Depending on the system and on the design equation used, those systems differ from their dimensions. Those systems led to overall surface areas between 0.6 ha and 1 ha. In the next stage that will take an interest in studying the feasibility of the project, the decision will be made in favor of one of the calculated systems in compliance with the accuracy and site specifications that are still to be studied.