Investigating the working efficiency of natural wastewater treatment systems: A step towards sustainable systems

Globally, wastewater is a vital resource and requires appropriate treatment management strategies. Wastewater has become a major source of irrigation in the peri-urban areas of developing nations. With the increasing amount of wastewater generation, there are several complications in using treatment systems in terms of installation, operation and maintenance, and size in developing countries. Recently, natural treatment systems are gaining popularity due to less cost and maintenance and have been preferred in peri-urban settings. In this study, the working efficiency of the natural systems was assessed from case studies from Vizianagaram, Andhra Pradesh, India. The nutrient (Phosphorous and Nitrogen content) and organic matter removal efficiency of four natural treatment systems (NTS) having different operation maintenance and loading rates were investigated. The study showed that natural treatment systems have good potential for peri-urban wastewater treatment. It was also observed that waste-stabilization based system perform better than those based on duckweed and hyacinth plants. Regularly maintained and operated systems show removal efficiency on the order of 80% for organic and nutrients and performed better than others. The study indicates that decentralized, adequately maintained Waste Stabilization Ponds (WSP) offer a viable, self-sustaining and eco-friendly alternative for wastewater treatment to supply irrigation water in rural areas.

AN EXPERIMENTAL STUDY ON TREATMENT OF DOMESTIC WASTEWATER BY NATURAL SOIL

In recent centuries, issues such as efficient use of water resources, water quality and water supply have become important for many countries. Countries have focused on developing strategies that can protect water and using water in the most efficient way including treatment of wastewater. In addition, it has become important to provide sustainability of the natural treatment systems instead of complex and expensive wastewater treatment facilities that are rapidly developing. On the other hand, the researches on natural treatment of wastewater are still inadequate. Therefore, the feasibility and performance of new stragtegies about natural treatment systems should be developed and evaluated. For this purpose, a pilot facility was developed which utilizes a natural soil-column with different gradations in order to provide the treatment of domestic wastewater. In this way, not only the wastewater treatment performances of different soils but also some engineering properties of soils affected by wastewater filtration were examined. As a result of this research, it was found that soil filtration can be effective in the treatment of wastewater subjected to pre-sedimentation and can be affected by the pollutant load of the filtration environment.

Constructed Wetlands

Constructed Wetlands are an alternative, promising technology for water/wastewater treatment and pollution mitigation. They belong to the wider category of natural treatment systems. The main principle is to exploit natural materials (gravel, sand, plants) and naturally occurring processes under controlled conditions for treatment purposes. Constructed Wetlands have been characterized as an environmentally friendly, sustainable technology which provides multiple economic, ecological, technical and societal benefits. It is a rising technology which can be effectively used for domestic, municipal and industrial wastewater treatment, as also for sludge dewatering and drying. This chapter presents an overview of this eco-technology; its different types, main design considerations and various advantages over conventional treatment methods.

Management of wastewater in rural districts of Istanbul metropolitan municipality

Decentralized systems play a big role in wastewater treatment in rural areas. The aims of this study are to address the wastewater treatment and disposal problems for rural districts of Istanbul, to discuss the efficiencies of currently operated systems and to offer new appropriate wastewater treatment systems for small communities having a population up to 5,000. The management and final disposal alternatives for sludge generated in septic tanks are also discussed within the scope of this study. A sequencing batch reactor (SBR) system serving 2,500 people and a hybrid constructed wetland system serving 500 people are presented as case studies. A thorough evaluation based on the capacity and performance of the existing wastewater treatment systems in rural districts revealed that a number of these systems are not operating at their optimum. Improperly constructed sewer lines receive a lot of infiltration and inflow (I & I) after rainfall events, decreasing treatment performance and causing operational difficulties. Natural treatment systems such as constructed wetlands prove a viable alternative in these communities, especially for villages with populations less than 500 people.