Aquatic plant/microbial water purification system

A multi-stage active biological waste water treatment Apparatus. An anaerobic, sludge settling first lagoon or chamber has a distributed piping system providing multiple, spaced outlets for the inflow of waste water; the multiple outlets distribute the buildup of sludge within the anaerobic chamber, which otherwise tends to block influent pipe outlets, by shifting flow from one outlet pipe to the next as sludge builds up. A controlled flow aspirator system then injects air into the odoriferous effluent from the anaerobic chamber as part of the natural water flow out of the anaerobic chamber into the first of a series of biological treatment chambers, without exposing the effluent to local surroundings. Within an aerobic duckweed treatment chamber, a rotating effluent outflow pipe retains an effective biomass of duckweed for the treatment process, yet, as desired, removes a chosen quantity of this growing biomass for harvesting. The final treated effluent, substantially free from fecal coliform bacteria, is then partially diverted and recirculated, being sprayed to form an upper layer of substantially pure, fecal coliform free, oxygenated water, covering the anaerobic waste water within the initial anaerobic chamber, eliminating release of odors.

BACKGROUND OF THE INVENTION 
This in to the field of biologically active water purification systems 
using combinations of plants and microbial action, and to the physical 
construction of same. 
It is known that biological pollution control systems can be of great 
effectiveness in purifying organic wastes within water. Typical systems 
are described in, for example, Wolverton, U.S. Pat. No. 4,959,084 
disclosing an air pollution treatment facility flowing air through a waste 
water fluid and then flowing the combined fluid and pollutants through a 
combination of rocks, plants and microbes for purification. 
One typical plant known to be of special effectiveness in converting and 
reducing organic contaminants in water go by the typical name of duckweed, 
a small floating aquatic plant usually found in mixtures of three Genera: 
Spirodela, Lemna, and Wolffia. Such plants are known to be extremely small 
floating upon the surface of the water and at a distance look like algae. 
Since they are not rooted into soil, various devices have been developed 
to promote and produce a uniform floating coat of these plants on a 
treatment pond. Typical ones are shown in U.S. Pat. No. 4,536,988 to Hogan 
disclosing a floating containment barrier grid structure for containing 
duckweed. 
The general field of treatment of waste waters include U.S. Pat. No. 
4,522,722 to Nicholas disclosing subsequential treatment first and 
anaerobic zone and then flowing the treated liquid through an aerobic zone 
producing sequentially reduction and oxidation as a method of removing 
sludge and in dealing with the retained nitrogen and phosphorus in the 
resulting water. 
U.S. Pat. No. 4,209,388 to DeFraites discloses a sewage treatment method in 
which sequential ponds are gravity fed from a first pond containing algae 
for aerobic composition followed by a second pool for removal of the algae 
and a third "polishing" pond which provides an oxidation state. 
U.S. Pat. No. 4,333,837 to Plosz, et al discloses a structure and apparatus 
providing for flow path water, one aquatic plant region and Wolverton, 
U.S. Pat. No. 4,415,450 disclosing sequential steps of subjecting the 
waste water to an anaerobic settling step passing the liquid through an 
anaerobic filter cell once it percolates up to an aerobic treatment stage. 
U.S. Pat. No. 4,793,929 to Kikuth discloses a two-stage treatment process 
and summarizes advances pass the classic activated sludge process for 
treatment of sewage. 
SUMMARY OF THE INVENTION 
The invention discloses a structure for a multi-stage active biological 
waste water treatment apparatus which particularly facilitates multi-stage 
anaerobic and aerobic treatment of waste water through biological 
processes to provide a continuing and controlled integrated system for 
removal and harvesting of excess biomass, removal of nutrients from the 
waste water and a method of controlling the undesirable odors now present 
in open anaerobic lagoons. 
The apparatus comprises first a unique construction for an anaerobic, 
sludge settling first lagoon or chamber in which a distributed piping 
system provides multiple, spaced outlets for the inflow of waste water; 
the multiple outlets distribute the buildup of sludge within the anaerobic 
piping system, which otherwise tends to block pipe outlets, shifting flow 
from one outlet pipe to the next as sludge builds up. 
A controlled flow aspirator system then injects air into the odoriferous 
effluent from the anaerobic chamber as part of the natural water flow out 
of the anaerobic chamber into the first of a series of biological 
treatment chambers, without exposing the effluent to local surroundings. 
The first treatment chambers typically use duckweed. The invention provides 
a unique, simple duckweed harvesting apparatus for retaining the growing 
biomass of duckweed that occurs naturally as a result of the treatment 
process, yet, as desired, removing a chosen quantity of biomass from the 
duckweed treatment chambers to a duckweed harvesting chamber, where the 
biomass may be conveniently separated from the intermediate partially 
treated wastewater. 
A final treatment stage using high density grasses to form a filter mat in 
an aerobic chamber producing the necessary high surface area for enhanced 
bacterial action replacing the mechanical filters and rocks of currently 
known filter and significantly increasing, through plant utilization, the 
removal of nitrogen, ammonia and nitrate products from the effluent. 
The final treated effluent, substantially free from fecal coliform 
bacteria, is then partially diverted and recirculated, being sprayed to 
form an upper layer of substantially pure, fecal coliform free, oxygenated 
water, covering the anaerobic waste water within the initial anaerobic 
chamber. This surface water serves to substantially eliminate odor release 
from the anaerobic chamber surface and at the same time provide the 
necessary agitation at significantly less energy costs than the current 
waste water aerators. 
It further has the advantage over prior art aeration apparatus of not 
producing an aerosol which would contaminate the atmosphere with disease 
causing microorganisms which may be present in raw sewerage. 
A dual channel system for flow of the waste water allows the waste water to 
be diverted from one channel to another for the performance of maintenance 
or the harvesting of grasses. 
It is thus an object of the invention to disclose a substantially automatic 
waste water treatment apparatus which is more resistant than the prior art 
to a single point buildup of sludge within the initial sludge collection 
and treatment chamber. 
It is a further object of the invention to disclose a waste water treatment 
apparatus which substantially reduces the release of odors and 
contaminating microbial organisms from the initial untreated waste water. 
It is a further object of this invention to disclose a construction for an 
anaerobic initial treatment chamber which is substantially free from the 
release of undesirable odors or microbial contamination. 
It is a further object of this invention to disclose a waste water 
treatment facility which provides a simple, low-cost means of removal and 
harvesting of duckweed biomass growth resulting from the organic reduction 
by plants of waste water contaminants. 
It is a further object of the invention to disclose a construction for an 
anaerobic sludge treatment chamber which is resistant to blockage from 
sludge buildup, and which more evenly distributes sludge deposits. 
It is a further object of this invention to disclose a waste water 
treatment apparatus which is substantially free of odor release, which has 
substantially reduced opportunity for microbial contamination of the 
atmosphere, and which provides for the ready harvesting and removal of 
biomass created during reduction of waste water contaminants. 
These and other objects of the invention may be more clearly seen from the 
detailed description of the preferred embodiment which follows.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1 I show in an angled view with side section cutaway the 
apparatus of the invention. Waste water to be treated enters through 
influent point or piped tube into an anaerobic sludge collection and 
digestion chamber 1. As is known this waste water is a combination of 
sludge and organically and chemically contaminated water. Influent to pipe 
2 extends horizontally within the water level 4 of the anaerobic chamber 1 
periodically emanating from the sides of influent pipe 2 are sludge 
distribution pipes 3 extending downward at an angle to a midpoint within 
the water liquid level within an anaerobic chamber 1. Extending parallel 
to but above influent pipe 2 is a purified water spray pipe 20, which in 
the preferred embodiment of the invention is an elongate plastic or pvc 
pipe having a plurality of holes or spray opening on its top surface along 
its length. These spray holes are provided at varying angles to provide 
for a spray 25 of purified water as hereinafter described. 
Purified water spray pipe 20 is supported at water level 4 within the 
anaerobic sludge chamber 2 by means of a plurality of floats 21 so that 
pipe 20 will float at exactly surface level, the spray being just above 
surface level 4 of the liquid of the anaerobic chamber. 
At an end of the anaerobic sludge treatment chamber 1, distal of the 
entrance of influent pipe 2 is an anaerobic chamber effluent pipe 5. 
Effluent pipe 5 is a hollow vertical stand of pipe having at an 
intermediate point a horizontal run of pipe extending through anaerobic 
chamber walls to a duckweed chamber 6. Waste liquid flowing through 
anaerobic chamber effluent pipe 5 enters a circulatory aspirator 7 which 
aerates the effluent prior to its introduction into duckweed chamber 6. 
As is known, duckweed is an extremely small floating plant, which, not 
being rooted in soil, requires mechanical means to form a uniform duckweed 
coat on the surface of the liquid within duckweed chamber 6; these 
duckweed colony retainers 8 can be in the form of floating plastic pipes 
or in the form of other duckweed retention covers or grids as are well 
known in the art. 
At the distal end of duckweed chamber 6 is placed duckweed harvest means 9. 
Duckweed harvesting means 9 is a rotating T-pipe mounted on an effluent 
pass-through pipe extending through the wall interconnecting duckweed 
chamber 6 and harvesting chamber 11. 
Duckweed harvesting means 9 may be rotated from a vertical to a horizontal 
position; in the vertical position, a distal end of harvesting means 9 
extends down to within water level 4 of the duckweed chamber 6, permitting 
the free flow of treated effluent into the harvesting chamber 11 but 
preventing the flow of any duckweed into harvesting chamber 11, the 
duckweed floating as a layer upon the top level 4 of the liquid within the 
duckweed chamber 6. The open end of Duckweed harvesting means 9 serves as 
a siphon break, preventing siphoning of the Duckweed chamber 6 or back 
siphoning from duckweed harvesting chamber 11. 
Duckweed harvesting means 9 may be rotated to a substantially horizontal 
position, bringing both openings co-level with liquid level 4 within the 
duckweed chamber 6. When harvesting means 9 is rotated horizontally, 
duckweed 10 flows with the liquid effluent into duckweed harvesting means 
9 and thence through into harvesting chamber 11 forming a thick layer of 
collected duckweed 10 within harvesting chamber 11. 
The harvesting chamber effluent pipe 12 acts as a separator; extending 
downward into the level of the water within harvesting chamber 11, it 
permits liquid effluent to flow into the aquatic plant chamber 13 but 
prevents escape of duckweed into the aquatic plant chamber 13. 
When it is necessary to harvest duckweed due to its growth within duckweed 
chamber 6, duckweed harvesting means 9 may be rotated to a horizontal 
position. Duckweed flows readily into harvesting chamber 11 where it can 
be mechanically removed by skimming or other harvesting techniques as are 
known in the art. 
It is to be noted that effluent pipe 5, aspirator 7, duckweed harvesting 
means 9 when rotated to a vertical position, and duckweed harvesting 
chamber effluent pipe 12 have vertical openings extending into the air; 
this provides a siphon break and prevents siphoning from any chamber into 
the next sequential chamber. All flow of waste water through the apparatus 
is as a result of water levels induced by flow of influent into pipe 2, 
not by siphoning, so that desired stepped liquid levels 4 are maintained 
within each of anaerobic sludge chamber 1, duckweed chamber 6, duckweed 
harvesting chamber 11, aquatic plant chamber 13, and purified water 
chamber 22. The positioning of the horizontal through sections of each 
respective effluent pipe thereby establishes the respective liquid levels 
4 within each of the aforesaid chambers and, as shown in FIG. 3, the 
apparatus is designed so that each chamber is stepped for liquid flow in a 
downward direction from the highest level being in an anaerobic sludge 
collection chamber 1 to the lowest level in purified water chamber 22. 
Within aquatic plant chamber 13 are provided aquatic grasses such as 
torpedo grass or switch grass 14 rooted into a soil root area 15 embedded 
below liquid level 4 within the aquatic plant chamber 13. It has been 
determined that the provision of aquatic plants 14 which are any of a 
number of known aquatic grasses having extremely high density and great 
surface areas, provide for an increased biologically active surface 
filtration area over the prior rock filters or mechanical filters of the 
art and thereby provides for an enhanced purification over the filters. 
Further, the provision of aquatic grasses in lieu of mechanical rock 
filtration results in the growth processes of the aquatic grasses removing 
substantially large amounts of dissolved nitrogen, ammonia and nitrates, 
thus lessening a known problem in the prior art which had formerly been 
met by means of chemical filtration, and adds to the microbial reduction 
of ammonia to nitrates. 
Aquatic plant chamber 13 is typically an elongate chamber so as to promote 
substantial mixing and flow of the waste water within the roots of the 
provided plants from the point of entrance to a point of exit. The water 
emitted from the plant chamber 13 through plant chamber effluent pipe 16 
is substantially purified, free of fecal coliform and has substantially no 
remaining organics or ammonia and thus has a very low biological oxygen 
demand (BOD). This water may be released through purified water release 23 
to the environment without damage or harm to the environment. 
A purified water take up pipe 18 permits the removal of a portion of the 
purified water from purified water chamber 22 which is then pumped through 
lift pump 19 and provided under pressure into purified water spray pipe 
20. 
Purified water spray pipe 20 then sprays a layer of purified water which 
forms a floating purified water coat at an upper level above the 
substantially anaerobic liquid treatment zone within the anaerobic sludge 
chamber 1. 
This spray of purified water provides the necessary upper level aeration 
formerly provided by waste water aerators; the spray is of purified water, 
not contaminated waste water and thus if apparition and spray transport in 
the air transports neither odoriferous byproducts such as sulfides nor is 
there a chance of transporting aerosol borne microbes or bacteria which 
may well pose a health hazard in the waste water areas of the prior art. 
Thus, the most conspicuous and objectionable aspect of a sewerage and waste 
water treatment plant, the strong and unpleasant odors emitted from the 
initial stage of anaerobic sludge treatment, are substantially eliminated. 
In addition, the organically active waste products taken up in the duckweed 
or in the aquatic grasses and the mineral contaminants which are taken up 
by the aquatic grasses may be removed by periodic harvesting of the 
duckweed and the aquatic grasses. To enhance the harvesting of aquatic 
grasses and to permit ready maintenance it is preferred that the apparatus 
of the invention be constructed, as shown in FIG. 2 as two parallel 
channels of treatment, thus providing both redundancy in the event of 
failure of an individual pump, pipe or connection and permitting one of 
the two channels to be temporarily taken out of service and drained for 
necessary maintenance or for aquatic grass harvesting while continuing the 
treatment of waste water through the alternate channel. 
It can thus be seen that the invention as disclosed is particularly 
advantageous construction for a multi-stage biologically active waste 
water treatment facility and the invention extends beyond the specific 
embodiment given to the variations as are implicit in the claim.