Integrated hydroponic and fixed-film wastewater treatment systems and associated methods

Abstract

The wastewater treatment systems have a plurality of treatment zones including a first reactor for supporting biofilms for reducing a concentration of organics and solids from wastewater to be treated and for cyclically nitrifying and denitrifying the wastewater therein. A second reactor is for supporting biosolids, the supporting means including elements for digesting suspended solids in water exiting the first reactor. A portion of the water exiting the second reactor is recycled to the first reactor.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application is a continuation of and incorporates by reference co-pending application Ser. No. 10 / 294,450, filed Nov. 14, 2002, now U.S. Pat. No. 6,811,700, entitled “Integrated Hydroponic and Fixed-Film Wastewater Treatment Systems and Associated Methods,” which application claimed priority to provisional application Ser. No. 60 / 333,203, filed on Nov. 14, 2001, entitled “Integrated Hydroponic and Fixed-Film Wastewater Treatment Systems and Associated Methods,” both of which are commonly owned with the present invention and which are incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to wastewater treatment systems and methods, and, more particularly, to such systems and methods for wastewater treatment that are nonchemically based. [0004] 2. Description of Related Art [0005] Wastewater treatment via “natural” means, i.e., without the addition of chemica...

AI Technical Summary

Benefits of technology

[0010] The present invention provides a wastewater treatment system and method that are less land intensive than previous systems, as well as combining the advantages of a plurality of remediation techniques. The present invention has a smaller footprint than previously disclosed wetlands, reduces undesirable characteristics of an influent, and has a low yield, i.e., low proportion of matter needing disposal.

[0012] The wastewater treatment systems and methods of the present invention are amenable to the treatment of, for example, but not intended to be limited to, domestic wastewater, industrial waste or process water, stormwater, urban runoff, agricultural wastewater or runoff, and even biological sludges. The systems are capable of handling a flow range of approximately 2000-2,000,000 gal / day. The types of contaminants that can be treated in the system include suspended particles, nutrients, metals, simple organics (oxygen-demanding substances), and synthetic or complex organics. The undesirable characteristics typically desired to be remediated include, but are not intended to be limited to, average biological oxygen demand (BOD), average total suspended solids (TSS), total nitrogen, and concentration of oil and grease. The systems of the present invention can reduce BOD to <10 mg / L, TSS to <10 mg / L, and total nitrogen to <10 mg / L.

Problems solved by technology

A negative aspect of such systems is that they are very land-intensive, requiring roughly on the order of 100 times as much land area as a conventional treatment plant, or, in terms of capacity, as much as 30-40 acres per 106 gallons of wastewater treated per day unless other treatment processes are incorporated into the constructed wetlands

These systems have been shown to frequently fail, however.

Failure is manifested as the upstream gravel tends to become clogged with biosolids, permitting the influent to bypass the clogged region and pass substantially untreated to a downstream region.

Ultimately the gravel becomes so clogged that design wastewater treatment is substantially compromised.

Although this root zone treatment method can provide advanced secondary treatment effluent, its application is limited by climate to approximately 5% of the United States.

The large treatment footprint of water hyacinth treatment systsems prohibits enclosure in greenhouses for almost all economically viable applications.

Among the problems encountered with root zone / activated sludge technology is that the clarifiers employed do not scale well when the size of the system is reduced beyond a certain point.

In addition, operator qualifications are high for activated sludge systems, adding to the expense of running the system.

Root zone / activated sludge technology has been known to digest in situ a large fraction of the biosolids produced and maintained within the treatment system, thereby reducing system biosolids yield.

Lack of recycled biosolids substantially degrades the treatment performance of the activated sludge treatment element.

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