Conventional Methods of Waste Water Treatment

Waste Water Treatment

Inadequately treated waste water poses hazards such as water-borne diseases and water-body pollution. People generate wastewater (sewage) in numerous ways, including laundry and toilet use. To prevent pollution and ensure public health, waste water ought to be treated adequately. Today, waste water is not so much a problem as it was in earlier centuries, a trend that is attributable to the development of efficient sewer lines and treatment plants, otherwise referred to as centralized wastewater collection and treatment facilities. Not long ago, however, these were not as effective as they are today, and worse still, were not available to a majority of the population. People used the conventional decentralized waste systems to take care of, among others, the black waters, and still managed to lead hygienic lives.

Septic Systems: these consisted of a "septic tank, the drain field, and the soil beneath the drain field" (NCSU, 2013). The tank, which acts as a temporary storage, is linked to the drain field through a buried pipe. In the tank, solids are separated from liquids and stored at the bottom as sludge (UNL, 2011). The drain field delivers the septic effluent from the tank to the soil, which filters disease-causing bacteria and chemicals, while retaining useful ones such as phosphorus as the effluent infiltrates into the groundwater.

Lagoon Systems: sewage is discharged into a small mass of water referred to as a lagoon (UNL, 2011). Decomposition occurs near the surface through aerobic means and elsewhere, anaerobically, separating solids from liquids. The liquids then evaporate, leaving the solid waste residue (sludge) at the bottom (UNL, 2011).

Other common ways included the use of privies and cesspools, whose modes of operation were similar to that of the septic tank. These conventional systems could only serve a single household, and required the periodic removal of the sludge stuck at the base. The sludge was then disposed off as waste.

The centralized systems of water treatment today, though more efficient than the conventional ones, require large amounts of moving water, and are not, therefore, an effective health management technique in areas that are prone to water shortages (Rapaport, 1995). These regions, to this end, often make use of alternative methods of water treatment that are merely improvements of the conventional decentralized systems. In this case, the conventional methods are modified as to recover human excreta as a resource, as opposed to disposing it off as waste (Rapaport, 1995). These treatment options make use of natural processes to convert human excreta into fuel or even fertilizer. The most common of these treatment methods include;

The use of waterless biological toilets: these rely on the composting process of soil-based microorganisms, which decompose human waste into humus (Rapaport, 1995). These do not use water. Instead, air is pulled in through the toilet's pile to facilitate microorganism activity, which slowly decomposes the waste as the effluent percolates through the soil, leaving liquids to leach and be treated the same way as grey water (Rapaport, 1995).

Waste water gardens: in this case, waste water from households is led into a sealed septic, and then into a specially-designed subsurface wetland cell which keeps it below the soil, preventing odors, and at the same time treating the effluent through a three-phase microorganism composting process that converts the solids to humus, and leaves the liquids to leach into the soil as grey water (Rapaport, 1995).