Purification of industrially contaminated groundwaters using controlled ecosystems

Abstract

Pollution of ground and surface waters by industrial processes is a widespread and very serious environmental issue. While solutions exist to many of these problems, they frequently remain unused because of high costs often related to the broad spectrum of chemistry involved at individual sites. This paper presents, at bench scale, an amelioration procedure involving miniature ecosystems controlled by algal turf scrubbing (ATS) as applied to contaminated groundwater from a New Jersey (USA) industrial site. The groundwater, with a COD of 1300 mg/l and a TSS of 2000 mg/l, presented a broad array of inorganic elements including magnesium, iron and manganese and minor heavy metals with a suite of twenty synthetic organic compounds. The organic compounds included trichloroethylene, vinyl chloride and acetone, among others, for a concentration averaging 1071 mg/l. On the first experimental run, using metal halide lighting for driving algal photosynthesis, the ATS/microcosm process described herein purified the contaminated water to drinking water standards for all inorganic elements and organic compounds except trichloroethylene and dichloroethylene. Subsequent runs, with low levels of UV-B applied to the ATS, achieved full drinking water standards. An examination of losses due to volatilization showed that minor losses of chlorinated hydrocarbons were also largely avoided with the addition of UV-B. Vinyl chloride was not detected in significant quantities in the volatile suite taken from air over the ATS unit either before or after the supplemental addition of UV-B. ATS is a low-cost ecotechnology that combines metabolic and adsorptive uptake by algae, precipitation at high pH and degradation under a saturated oxygen/UV radiation regime to ameliorate complex industrial wastewaters.