Treatment of Greywater Using Bio filtration and Permeable Pavement Systems

Municipal wastewater can be divided into two categories, greywater and black water. Greywater occupies about 75% of total wastewater and are relatively less polluted than the black water. Reuse of greywater is becoming popular in many arid and semiarid regions in order to reduce the municipal water demand. They can be reused for groundwater recharge, landscape irrigation and for toilet flushing. However, the main challenges are their collection, storage and selection of the appropriate treatment system. The United Arab Emirates (UAE) is located in a hyper arid region, having an annual average rainfall of less than 100 mm. Reliable survey data for surface water resources are not available here. Three main sources of water resources in the UAE are groundwater, desalinated water and reclaimed wastewater. Despite their scarce water resources, residential water consumption in the UAE is significantly high, of which more than half of the municipal water are used for outdoor activities. The water demand reduction and diversification of water sources are very important for the security of its urban water supply. The study investigated the quantity and characteristics of greywater, and the efficiency of two alternative treatment systems, the biofiltration and the permeable pavement with an underlying reservoir. The study was conducted in the city of Al Ain. Both treatment systems are conventionally used for urban stormwater treatment. They are popularly known as the Water Sensitive Urban Design (WSUD) systems. Laboratory scale prototypes of both systems were prepared and investigated. The estimated greywater generation rate was found about 190 liter/capita/day. The ablution and laundry greywater exhibits the least and most deteriorated greywater, respectively. Both systems performed well in improving the greywater quality, but the vegetative biofiltration unit performed better than the permeable pavement unit. The study revealed that the permeable pavement with an underlying reservoir can be used as a storage unit and subsequent treatment can be achieved in the vegetative biofiltration system. Both systems are well fitted within the urban landscape of UAE

Quantitative assessment of residential water end uses and greywater generation in the City of Al Ain

Diversification of water sources and water demand reduction are two vital tools in maintaining the security of urban water supplies in the United Arab Emirates (UAE). Reuse of greywater for non-potable end uses can be an effective alternative, but this resource has not yet received much attention in the UAE. Since the generation of greywater significantly differs from country to country – depending on age, gender, habits, lifestyle, living standards and the degree of water abundance – an attempt was made to estimate internal water consumption and greywater generation in the city of Al Ain, UAE. The frequency and water requirement for personal water uses (e.g. showers, ablutions, teeth brushing, hand washing, face washing and toilet flushing) and family water uses (e.g. laundry, dish washing and house cleaning) were estimated from about 100 villa-type detached homes randomly distributed across the city. A frequency analysis was carried out using normal, lognormal, gamma and logistic distribution. The estimated average generation rate of greywater was found to be 192 litres per capita per day, which is about 69% of the average internal water consumption. The generated greywater originates from showers (49%), ablutions (18%), laundry (10%) and washbasins (23%). Based on average quantities, it was shown that the generated greywater is sufficient to fulfil the non-potable water demand in houses, but further, more rigorous, investigation is required