Biological treatment of greywater using sequencing batch reactor technology

Greywater as a sustainable source for development of green roofs: Characteristics, treatment technologies, reuse, case studies and future developments

Municipal activities are one of the most important water users worldwide; thus, the treatment and reuse of greywater for non-potable purposes helps to reduce a remarkable amount of consumed water within urban communities. To achieve greywater reuse standards, and remove surfactants, micropollutants, organic matters, microorganisms and other pollutants various methods including physical, chemical and biological processes have been used. Treated greywater can be used on site for different purposes: carwash, toilet flushing, fire protection, green roofs, green walls, non-food irrigation etc. Among them, the use of greywater is very important in the expansion of the green roofs. Green roofs offer many benefits to urban areas such as decreasing air pollution, reducing building cooling needs, promoting mental health of habitants, noise reduction and aesthetics improvement. Therefore, this article provides an overview mainly from two aspects, the possibilities of greywater reuse by studying the characteristics and available options for greywater treatment and its benefits toward the developing green roofs.

Extended use of grey water for irrigating home gardens in an arid environment

The use of treated grey water (GW) for home gardens, peri-urban agriculture and landscaping is becoming popular in many water stressed countries such as Oman. This study aims to investigate the treatment efficacy, health and chemical concerns, cost-benefits and maintenance protocol of a GW treatment system as well as the effect of irrigation with GW on crop yield. Therefore, a decentralized homemade GW treatment system was installed in a newly constructed house in Muscat, Oman and studied over a 2-year period. The treated GW was found to be suitable for irrigation as per Omani standards. GW when mixed with kitchen effluent substituted the use of nutrient supplements for plants and did not show any harmful chemical or biological contamination. The capital cost of the system was around US $980, and the annual operating cost was US $78 with annual income and savings from the system being around US $572 indicating a payback period of nearly 2 years. It was found that the system required simple but regular maintenance particularly cleaning of the top layer of the filter. It can be concluded from this study that such a GW system should be technically, economically and environmentally feasible in Oman. Also, wider acceptance by the general public to the idea of GW reuse will help in mitigating the water shortage problem of the country to some extent.

Wastewater and sludge management and research in Oman: An overview

It is well recognized that management of wastewater and sludge is a critical environmental issue in many countries. Wastewater treatment and sludge production take place under different technical, economic, and social contexts, thus requiring different approaches and involving different solutions. In most cases, a regular and environmentally safe wastewater treatment and associated sludge management requires the development of realistic and enforceable regulations, as well as treatment systems appropriate to local circumstances. The main objective of this paper is to provide useful information about the current wastewater and sludge treatment, management, regulations, and research in Oman. Based on the review and discussion, the wastewater treatment and sludge management in Oman has been evolving over the years. Further, the land application of sewage sludge should encourage revision of existing standards, regulations, and policies for the management and beneficial use of sewage sludge in Oman.

IMPLICATIONS

Wastewater treatment and sludge management in Oman have been evolving over the years. Sludge utilization has been a challenge due to its association with human waste. Therefore, composting of sewage sludge is the best option in agriculture activities. Sludge and wastewater utilization can add up positively in the economic aspects of the country in terms of creating jobs and improving annual income rate. The number of research projects done on wastewater reuse and other ongoing ones related to the land application of sewage sludge should encourage revision of existing standards, regulations, and policies for the management and beneficial use of sewage sludge in Oman.