This study aims to discern the domestic gray water (GW) sources that is least polluting, at the urban households of India, by examining the GW characteristics, comparing with literature data, reuse standards and suitable treatment technologies. In view of this, the quantitative and qualitative characteristics of domestic GW originating from bath, wash basin, laundry and kitchen sources are determined and compared with established standards for reuse requirements. Quality of different gray water sources is characterized with respect to the physical, chemical, biological, nutrient, ground element and heavy metal properties. The pollutant loads indicate that the diversion techniques are not suitable for household application and, therefore, treatment is necessary prior to storage and reuse. It is observed that the total volume of GW generated exceeds the reuse requirement for suggested reuse such as for flushing and gardening/irrigation. In spite of generating less volume, the kitchen source is found to be the major contributor for most of the pollutant load and, therefore, not recommended to be considered for treatment. It is concluded that treatment of GW from bathroom source alone is sufficient to meet the onsite reuse requirements and thereby significantly reduce the potable water consumption by 28.5 %. Constructed wetland systems and constructed soil filters are suggested as suitable treatment alternatives owing to its ability to treat highly variable pollutant load with lower operational and maintenance cost, which is more practical for tropical and developing countries. Keywords Gray water composition Á Gray water treatment Á Water treatment technologies Á Urban water reuse Á Domestic gray water

Poorly planned and uncontrolled urbanization in India has caused a variety of negative, often irreversible, environmental impacts. The impacts appear to be unavoidable and not easily mitigable due to the mounting public health problems caused by non-segregation of solid wastes at source and their subsequent improper management. Recently in India, non-governmental organizations (NGOs) and other civil society organizations have increasingly started to get involved in improving waste management services. Municipal solid waste management being a governmental function, the contribution of NGOs in this field has not been well documented. This study highlights the activities and services of Shuddham, an NGO functioning in the town of Puducherry within the Union Territory of Puducherry in South India. The NGO program promoted much needed awareness and education, encouraged source separation, enhanced door-to-door collection, utilized wastes as raw materials and generated more job opportunities. Even though source separation prior to door-to-door collection is a relatively new concept, a significant percentage of residents (39%) in the study area participated fully, while a further 48% participated in the collection service. The average amount of municipal solid waste generated by residential units in the Raj Bhavan ward was 8582 kg/month of which 47% was recovered through active recycling and composting practices. The study describes the features and performance of NGO-mediated solid waste management, and evaluates the strengths and weaknesses as well as the opportunities and threats of this system to see whether this model can sustainably replace the low-performance conventional solid waste management in practice in the town of Puducherry. The experiences from this case study are expected to provide broad guidelines to better understand the role of NGOs and their contributions towards sustainable waste management practices in urban areas.

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Over the past few years, the eco-industrial park (EIP) concept has been emerging as a significant driving force for sustainable industrialisation. Accumulating evidence indicates that the transition of existing industries into eco-industrial networking through industrial ecology (IE) principles would provide an excellent opportunity for facilitating such innovative industrialisation. A SWOT analysis was carried out to identify the potential and constraints for the successful implementation of an ecoindustrial park in the ecologically fragile coastal zone of Puducherry. The results indicated significant potential for EIP development with few challenges. The lessons learnt can be used to provide broad guidelines for facilitating EIP development in the Puducherry region and similar scenarios found elsewhere across the world, especially in developing countries.

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