Q1: Disposal to sewage in large cities, is done in

ANS:B - dilution

Dilution is a process used in sewage management to reduce the concentration of pollutants and contaminants in wastewater by mixing it with a larger volume of water. This method aims to decrease the intensity of pollutants to levels that are considered safe for discharge into the environment. In dilution, wastewater is typically released into a receiving water body such as a river, lake, or ocean. By discharging sewage into a large body of water, the sewage effluent becomes diluted as it mixes with the surrounding water, reducing the concentration of contaminants per unit volume. Dilution can occur naturally or be facilitated through engineered systems such as outfall pipes or treatment plants. In natural dilution, the flow of the receiving water body helps disperse and dilute the sewage effluent over a wider area, allowing for the natural processes of sedimentation, filtration, and microbial degradation to further reduce the pollutant levels. However, while dilution can help reduce the immediate impact of pollutants, it may not effectively address all types of contaminants, especially those that are persistent, toxic, or bioaccumulative. Moreover, overreliance on dilution as a sewage management strategy can lead to environmental degradation of water bodies and harm aquatic ecosystems. Therefore, while dilution may be a component of sewage management strategies, it is typically combined with other treatment methods such as biological treatment, chemical treatment, and advanced filtration to ensure the effective removal of contaminants and protect human health and the environment.