Proper removal and disposal of raw sewage are critical considerations in the general concept of human health and environmental safety. When disposing of sewage from inhabited areas, you need to consider life-generating and life-sustaining elements like food, heat, light, water, air, and living space. If the process compromises these elements, its impacts might be more detrimental than leaving the sewage intact.
The following are the steps involved in a safe raw sewage disposal process.
1. Off Site treatment
Raw sewage is potentially hazardous to the environment and human health. Therefore, it's crucial to engage in primary and secondary (biological and chemical) treatment before taking it to disposal sites.
Off Site sewer treatment is commonly done in urban areas with dense populations. Each house connects to a sewer pipeline running to a combined sewer. There is a wastewater treatment plant located at a lower elevation. The sewage is treated at this plant before being released into a river or an irrigation field.
2. On site treatment
The raw sewage is restricted to the primary treatment level where it's degreased, thickened, and digested. The grit is also removed before the sewage effluent is discharged into an ocean outfall or perennial river.
3. Secondary treatment
Even after being treated at the primary level, the effluent is still considered "raw sewage" regardless of being chlorinated or anaerobically digested. It still needs to be treated at the secondary level to bring the outfall product to acceptable standards to prevent it from tampering with the quality of the natural river water.
At the secondary treatment level, the effluent is mixed and reused for water supply down-river or pumped out using submarine outfall pipes to create a buoyant jet and diffusion plume in the river or ocean.
During treatment, raw sewage is separated into sludge and supernatant liquid. The former is spread out to dry and disposed of in settling beds and ponds, while the latter is discharged into waterways such as oceans, underground-unconfined aquifers, or rivers.
Alternatively, dewatered sewage sludge can be disposed of at landfills that are permitted to accept such waste. If you plan to send the waste to a landfill, ensure that it meets all the site's waste acceptance requirements. Besides, ensure that the landfill has a waste management licence or pollution prevention and control permit.
However, landfill spaces are rapidly reducing. Therefore, waste management companies opt to use other ways such as anaerobic digestion to limit the volume of the garbage being disposed of in landfills. Beside saving landfill spaces, such disposal methods help to convert the waste into valuable energy and agricultural products like organic fertilizers.
Disposal of raw sewage may be challenging, but discharging the waste safely and responsibly is essential for protecting the environment and the public health. Human excrement and industrial waste are the major sources of disease-causing microorganisms such as viruses, bacteria, and parasites. By treating the raw sewage before disposing of it, you'll help enhance protection against diseases and environmental degradation.