Advantages of Individual Household Wastewater Treatment Systems

Households typically use water for a number of different purposes-sink, shower, and bathtub use, washing machine use, and so on. Although the resulting wastewater may seem relatively easy to treat, the use of chemicals in detergent and other household cleaning products can in fact raise the *BOD index value of the wastewater to as much as 200% higher than that of the organic sewage resulting from toilet use, thereby requiring more complex treatment.

With System-Z's combined septic tank system, both household wastewater and toilet waste are treated together. Once that combined input is processed by the system and reaches a BOD index value of 5 milligrams per liter (5 ppm), the resulting effluent is clean enough for fish to thrive in, and clean enough to be released into municipal water drainage systems discharging into rivers, seas, and oceans.

There are, however, countries or localities that prohibit the release of treated household wastewater into their public drainage systems. In the case of such prohibition, the effluent from System-Z-treated wastewater can be recycled on-the-spot for toilet and outside use. Indeed, a significant contribution to water resource conservation will be achieved when large numbers of households recycle their own wastewater.

OM Solar's System-Z is an individual household wastewater treatment system because it functions independently of any municipal sewage network.

Because of their advantages, local governments in Japan are increasingly promoting the use of individual, combined-septic tank household water purification systems. Conventional wisdom has held that municipal sewage networks based on centralized waste proces-sing and treatment points are the most cost-effective. Recently, however, that view seems to be changing as communities become larger and larger and sewage pipeline networks expand as a result.

Add to this the fact that in Japan, for example, investment in pipeline infrastructure has traditionally represented about 70%, on average, of a community's waste treatment budgetary allocations as compared to 30% for processing and treatment centers. With rapidly expanding pipeline networks, that ratio becomes even more weighted with respect to pipeline investment.

As opposed to a municipal sewage treatment system, whose maintenance is assumed by the local authorities, the maintenance of an individual household system is the responsibility of the homeowner who, depending on government policy provisions, may receive financial support for that purpose.

For local governments that are perennially saddled with budgetary problems, the advantages in promoting the use of individual household water purification systems are therefore obvious. Hence the growing trend in Japan for local authorities not only to sponsor seminars explaining the merit of these systems to potential users, but also to help defray, through partial subsidization schemes, the costs involved for homeowners who install them.

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