Among the practices mentioned in the question, treatment ofdomestic sewage before its release is the most appropriate and correct practice from the point of view of a healthy environment because it is an environmentally sustainable and does not add to the pollution. The first and second practices mentioned here will result in air pollution. The fourth practice will add to water pollution and affect the aquatic life. Besides, it will also disturb the food chain and food web. Hence, except the third practice, all are not the appropriate and correct practice from the point of view of a healthy environment.