Development of an on-site subsurface horizontal flow wastewater treatment system

This research attempted to determine the performance characteristics of an anaerobic upflow fixed-film biological reactor (ANFLOW), in series with a standard septic tank and a subsurface horizontal flow (SSHF) bed, for use as an on-site wastewater treatment system. Two wastewater treatment systems were studied in Pigeon Forge, Tennessee. The performance evaluation was based on the collection of wastewater samples. The samples were analyzed for pH, temperature, biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), ammonia, and fecal coliforms. The data collected showed that the ANFLOW unit in conjunction with the SSHF bed proved to be a very effective wastewater treatment system. The ANFLOW unit enhanced the septic tanks performance such that the SSHF bed could be reduced in size. System start-up was rapid for the SSHF bed because the ANFLOW unit served as pretreatment for the SSHF bed. The data collected showed that the SSHF beds studied tended to follow first-order reaction kinetics, where the organic removal efficiency of the SSHF bed tended to be independent of the influent concentrations and dependent on the length (directly) and flow (inversely). It was concluded that the SSHF bed was most likely an anaerobically controlled system that is not sensitive to the amount of oxygen diffusion into the SSHF bed for BOD and COD removal. In conjunction with the ANFLOW unit, the SSHF bed will provide an energy-effective on-site wastewater treatment process for residential areas and small commercial businesses.