Apparatus and a method for biological treatment of waste waters

An apparatus and a method for biological treatment of waste waters achieving biological oxidation of organic matter, biological nitrification and denitrification of nitrogenous compounds and biological removal of phosphorus and clarification of the treated waste water in a single reaction tank in a single suspended growth sludge system without the use of traditional compressors, mixers, recirculation pumps, piping and valving and without the use of the traditional clarifier.

FIELD OF INVENTION 
This invention relates to a system for biological removal of carbonaceous, 
nitrogenous and phosphorous compounds and suspended solids from waste 
waters and has for its object a provision of an apparatus capable of an 
efficient, reliable and unattended maintenance free operation at minimum 
capital, operational costs and consumption of energy. 
BACKGROUND TO THE INVENTION 
Overfertilization of surface waters and degradation of potable water 
sources in densely populated areas led to pollution control regulations 
calling for removal of nutrients in the treatment of municipal and 
industrial waste waters. Consequently, in the biological treatment of 
waste waters attention is being focused on single-sludge suspended growth 
system combining the processes of carbon oxidation, nitrification, 
denitrification and removal of phosphorus in one or more reactors without 
the intermediate clarification and without the addition of external carbon 
source for denitrification and without addition of chemicals for removal 
of phosphorus. 
It is known, that for a high rate biological removal of carbonaceous, 
nitrogenous and phosphorous compounds in a single sludge system it is 
necessary to maintain: (a) a high concentration of mixed microbial 
population in the biochemical reactor, (b) an efficient contact of the 
mixed microbial population with the incoming waste water, (c) an efficient 
mixing of the partially treated waste water with the incoming waste water 
and with the mixed microbial population for a short period without the 
dissolved oxygen being present in the reactor mixed liquor and for a short 
period with the dissolved oxygen being present in the reactor mixed 
liquor, and (d) a controlled withdrawal of the excess sludge. 
To comply with the above process requirements, the current treatment 
systems utilize biochemical reactors that require compressors and/or 
surface aerators for mixing and aerating the reactor mixed liquor in the 
aerobic reaction zones, mechanical mixers for mixing of the reactor mixed 
liquor in the anoxic zones, pumps for recirculating the reactor mixed 
liquor between individual zones and clarifiers that require sludge mixers 
or sludge scrapers and sludge return pumps, piping and valving etc. that 
make the treatment system operational, but complex and expensive and 
requiring considerable maintenance. 
Therefore, it is the object of this invention to provide an efficient 
treatment system in which all of the above process requirements could be 
met and the biological reactions could be carried out reliably at minimum 
cost and at minimum consumption of energy. 
More particularly, it is the object of this invention to provide a 
biochemical reactor that would provide and reliably maintain the 
conditions required for a high rate biooxidation of carbonaceous 
compounds, biological nitrification and denitrification and biological 
uptake of phosphorus in a single reactor and a single suspended growth 
sludge system. 
It is also the object of this invention to provide a simple and maintenance 
free biochemical reactor with high energy utilization efficiency in 
mixing, recirculating and aerating of the reactor mixed liquor without the 
use of the traditional compressors, surface aerators, mixers and 
recirculation pumps, that could be constructed from concrete, steel, fiber 
glass and or other suitable material. 
Another object of this invention is to combine the biochemical reactor with 
a clarifier into a simple treatment system not requiring compressors, 
pumps, surface aerators, mixers, piping, etc. for reliable operation, that 
could be easy to scale up or down for use in standardized package plants. 
It is another object of this invention to provide a treatment system that 
would be capable to operate reliably with high concentration of powdered 
minerals, activated carbon, saw dust, or their mixtures present in the 
system. 
Another object of this invention is to provide a system for biological 
treatment of waste waters capable of cyclic "on-off" operation to permit 
optimum utilization of energy at batch-wise flow conditions occuring in 
small package plants and particularly in single house sewage treatment 
systems. 
Other objects and features of the invention will be understood from the 
accompanying drawings and the following description of claims. 
SUMMARY OF THE INVENTION 
The present invention provides a biochemical reactor with a new type of 
mixing of the reactor content permitting operation of the reactor with 
high concentration of mixed liquor suspended solids, permitting formation 
of anoxic and aerobic zones within a single reaction tank and providing 
all process conditions required for biooxidation of carbonaceous material, 
biological nitrification and denitrification and biological uptake of 
phosphorus in a single suspended growth sludge system. 
The present invention provides a new type of transport of the reactor mixed 
liquor between the anoxic and aerobic zones automatically formed in the 
reactor, provides a new type of delivery and dispersion of the air into 
the reactor mixed liquor, provides a new type of mixing in the formed 
anoxic and oxic zones thus eliminating the need for the traditional 
compressors, air diffusers, surface aerators, mixers, pumps and the 
associated piping and valving. 
The present invention permits integration of the biochemical reactor with a 
clarifier into a treatment system that does not require the traditional 
sludge return pumps, air lifts, sludge mixers or scrapers, mechanical or 
air operated skimmers and the associated piping and valving. The treatment 
system of this invention is therefore simple, its operation reliable, the 
capital and operational costs reduced and the traditional maintenance 
eliminated. 
The biochemical reactor of this invention with minor adjustment can be also 
used with the various activated sludge process modifications and the 
existing activated sludge treatment plants can be modified to utilize the 
benefits of this invention to reduce maintenance and operational costs, to 
improve the treatment efficiency and to increase the plant performance.

DESCRIPTION OF THE PREFERED EMBODIMENT 
Before explaining the present invention in detail it is to be understood 
that the invention is not limited in its application to the details of 
construction and arrangement of parts illustrated in the accompanying 
drawings, since the invention is capable of other embodiments and of being 
practiced or carried out in various ways. Also it is to be understood that 
the phraseology or terminology employed herein is for the purpose of 
description and not of limitation. 
Reference is made first to FIGS. 1 and 2 for an explanation of one 
preferred modification of the apparatus of the present invention. As is 
there shown, the apparatus comprises a reaction tank 10 equipped with an 
inlet 13, the first solid wall partition 10.1, the second solid wall 
partition 10.2, the baffle 24.7 with openings 24.9, a multifunctional 
device 20 comprising an endless vertical belt 21 with horizontal chambers 
22, the belt 21 being supported by a drum 23 mounted on a shaft 23.5, a 
standpipe 24.5 with valve 24.6, the throat 50, the weir 15 equipped with 
baffles 16, the effluent exit pipe 14 and the excess sludge withdrawal 
pipe 18 equipped with valve 19. It should be apparent that the belt 21 can 
be constructed using various types of chains and can be supported by 
sprockets mounted on the shaft 23.5 instead of the shown drum 23 to 
achieve the same results. 
The first solid wall partition 10.1 is positioned inside the endless 
vertical belt 21 and is attached to two side walls of the reaction tank 10 
separating the reaction tank 10 into first reaction zone 11 and second 
reaction zone 12. The second partition 10.2 is positioned in parallel with 
first partition 10.1 alongside the vertical belt 21 and is attached to two 
side walls of said reaction tank 10. The top of said second partition 10.2 
is submerged in the liquid held in the second reaction zone 12, the lower 
portion of partition 10.2 is arranged diagonally in second reaction zone 
12 to form with partition 10.1 a funnel shaped aeration zone 24 located 
between first partition 10.1, second partition 10.2 and the two side walls 
of the reaction tank 10. The first reaction zone 11 and the second 
reaction zone 12 are in communication with each other under the aeration 
zone 24 via opening 30 formed by the bottoms of first partition 10.1 and 
second partition 10.2 and the two side walls and bottom of the reaction 
tank 10. The endless belt 21 is moving around first partition 10.1 and 
downwardly in the channel 24.4 formed between first partition 10.1 and 
second partition 10.2 and upwardly in first reaction zone 11. A vertical 
baffle 24.7 is located in parallel with partition 10.2 and is attached to 
the two side walls of the reaction tank 10. The top of the baffle 24.7 
extends above the level of the liquid held in the second reaction zone 12, 
the bottom of baffle 24.7 is positioned at the top level of the fluidized 
bed 12.1 of sludge maintained in second reaction zone 12. The partition 
10.2 and the baffle 24.7 form a channel 24.8 for recirculation of the 
sludge from the top of the fluidized bed 12.1 upwardly in channel 24.8, 
then downwardly in channel 24.4, then downwardly through the aeration zone 
24 to the bottom of reaction tank 10, then upwardly in the direction of 
arrows 28 through the fluidized bed of sludge 12.1. The baffle 24.7 and 
the three side walls of the reaction tank 10 form a clear well zone 12.2 
positioned above the fluidized bed 12.1 in the reaction zone 12 from which 
clear well the treated and clarified waste water is flowing via weir 16 
and pipe 14 out of the reaction tank 10 and the floating solids 
accumulated in the clear well 12.2 are skimmed and returned via openings 
24.9 into the aeration zone 24. 
When drum 23 rotates in the direction shown by arrow 25 the belt 21 with 
chambers 22 moves in the direction shown by arrows 26. The rotation of the 
shaft 23.5 and the drum 23 can be by an electric motor and is such that 
the upward and or downward speed of the belt 21 is in the range between 5 
to 100 cm/sec. The belt 21 may be built from a suitable chain and 
horizontal chambers 22 which chambers can be made from pipes, ducts or 
other horizontal channels. Chambers 22 have large openings 22.2 located on 
the top when the chambers are moving up in reaction zone 11 and small 
openings 22.3 for dispersion of the air located opposite to openings 22.2. 
As chambers 22 move upward in zone 11 they force to rotate the content in 
reaction zone 11 in the direction shown by arrows 27. At the same time 
chambers 22 are filled with the reactor mixed liquor and as they pass to 
the right side on the drum 23 at position 23.3 the content of chambers 22 
is emptied via openings 22.2 into the channel 24.4 and the chambers 22 are 
filled with air. As chambers 22 continue to move downward through channel 
24.4 the entrapped air is released via openings 22.3 into the downwardly 
moving mixed reactor liquor and the dispersed air bubbles move downwardly 
with the mixed reactor liquor into the aeration zone 24. The velocity of 
the downwardly moving reactor mixed liquor in channel 24.4 being greater 
than the rising velocity of the air bubbles, it prevents the air collected 
in the top portion of the aeration zone 24 to escape via channel 24.4 out 
from the aeration zone 24 and the air is then continuously redispersed 
within the aeration zone 24 by the recirculated mixed reactor liquor. In 
this way energy is not wasted on compression of the delivered air and 
therefore much less energy is used for aeration of the reactor mixed 
liquor in the apparatus of this invention than that used in the current 
art systems. 
Since the downward velocity of the reactor mixed liquor in aeration zone 24 
drops due to increased crossectional area of the aeration zone 24 the air 
bubbles tend to remain within the aeration zone 24 until substantially all 
air oxygen is absorbed into the recirculated reactor mixed liquor. In this 
way substantially all of the oxygen present in the air delivered into the 
aeration zone 24 by chambers 22 is used up in the process and therefore 
none of the energy used for pumping the air is wasted. To control the 
amount of oxygen dissolved in the reactor mixed liquor a small portion of 
the air collected in the aeration zone 24 may be bled off via stand pipe 
24.5 and valve 24.6. In this way the apparatus of the present invention 
utilizes much less energy to maintain the biological processes occuring in 
the reaction tank 10 than the amount of energy used in the current art 
systems. 
As chambers 22 move downward through channel 24.4 they force to flow the 
sludge from the top of the fluidized bed 12.1 from reaction zone 12 
upwardly through channel 24.8, then over the top of partition 10.2 and 
downwardly through channel 24.4 and aeration zone 24 to the bottom of the 
reaction tank 10, then upwardly in the direction of arrows 28 through the 
fluidized bed 12.1. In this way the fluidized sludge solids from the 
reaction zone 12 are continuously recirculated through the aeration zone 
24 and saturated with oxygen required by the biochemical reactions 
occuring in the fluidized bed 12.1. 
The fluidized sludge held in reaction zone 12 filters out all suspended 
solids present in the treated waste water so that the treated waste water 
collected in the clear well 12.2 located in reaction zone 12 is clarified 
and may be discharged via weir 15 and pipe 14 out of the reaction tank 10. 
The excess sludge accumulates in first reaction zone 11 and may be 
withdrawn from the reaction tank 10 via opening 17 located in the side 
wall of the reaction tank 10, pipe 19 and valve 18 continuously to control 
the removal of phosphorus or periodically if it is desired to reduce the 
amount of the produced excess sludge. The present invention therefore 
permits operation of the apparatus and purification of the waste water 
without the need for a traditional clarifier. 
It sould be apparent that an efficient apparatus for biological 
purification of waste waters can be constructed also without using the 
throat 50 located in reaction zone 11 to improve the rotation of the 
reactor mixed liquor therein, or without the standpipe 24.5, or by other 
modifications of the aeration zone 24, or modification of partition 10.1, 
partition 10.2 and baffle 24.7. It should be also apparent that the 
apparatus of the present invention can be combined with any additional 
treatment step and/or apparatus to further improve the quality of the 
purified effluent. It is also apparent that the excess sludge if desired 
can be withdrawn from the aeration zone 24 or from the fluidized bed 12.1. 
It should be also apparent that a cyclic operation of the apparatus of the 
present invention is feasible and can be arranged by a single timer switch 
controlling the operation of the electric motor rotating shaft 23.5. 
OPERATION 
The operation of the aforedescribed apparatus and the method of the 
biological treatment used therein consists of the following: 
(a) feeding the waste water via inlet 13 into reaction zone 11 of the 
reaction tank 10, continuously rotating the content in this zone by the 
multifunctional device 20 and continuously contacting the waste water with 
the rotating sludge solids in the absence of dissolved oxygen therein, 
(b) continuously pumping a predetermined volume of the mixed reactor liquor 
from reaction zone 11 by chambers 22 into the aeration zone 24, mixing the 
reactor liquor withdrawn from reaction zone 11 with sludge withdrawn from 
the fluidized bed 12.1 from reaction zone 12 and flowing by gravity a 
predetermined volume of the mixed liquor with sludge solids from the 
aeration zone 24 back into the reaction zone 11 via opening 30, 
(c) continuously recirculating the fluidized sludge from the top of the 
fluidized bed 12.1 upwardly through channel 24.8 then downwardly through 
channel 24.4 into the aeration zone 24, then to the bottom of the reaction 
tank 10 and then upwardly through the fluidized bed 12.1 maintained in 
reaction zone 12 and contacting the waste water with the fluidized sludge 
solids in the presence of dissolved oxygen therein, the fluidized sludge 
solids being composed of suspended solids and microorganisms accumulated 
in the reaction tank 10 due to processing of the waste water, or the 
fluidized bed 12.1 composed of powdered minerals, activated carbon and 
microorganisms as disclosed in my previous invention covered by U.S. Pat. 
No. 4,167,479 and Can. Pat. No. 1,036,720, or the fluidized bed 12.1 
composed of fine wood particles and microorgainsms as disclosed in my 
other previous invention covered by U.S. Pat. No. 4,188,289 and Can. Pat. 
No. 1,064,169, 
(d) continuously pumping air by chambers 22 into the aeration zone 24 and 
continuously dispersing the air therein into the downwardly recirculating 
mixed liquor and sludge, 
(e) continuously accumulating the excess sludge solids in the reaction zone 
11 and continuously or periodically withdrawing the excess sludge from the 
apparatus either from reaction zone 11 or from aeration zone 24 or from 
fluidized bed 12.1, 
(f) continuously discharging the purified waste water from the clear well 
12.2 via weir 15 and pipe 14 out of the apparatus and continuously flowing 
the floating solids collected in the clear well 12.2 via openings 24.9 in 
baffle 24.7 into the aeration zone 24. 
It should be apparent to those skilled in the art that the treatment method 
can be substantially modified by operating the belt 21 in a cyclic 
"on-off" mode or by modifying the openings in chambers 22 and pumping the 
mixing liquor from aeration zone 24 into the reaction zone 11. 
From the above description of the apparatus and the method of this 
invention it is evident that the invented apparatus and the adssociated 
treatment do not require the traditional compressors and air diffusers or 
surface aerators for aeration of the reactor liquor, do not require the 
traditional mixers to maintain the biological activity in the denitrifying 
stages of the treatment in reaction zone 11, do not require the 
traditional pumps for recirculation of the reactor liquor between the 
aerobic reaction zone 12 and the anerobic reaction zone 11 and do not 
require the traditional clarifier, sludge return pumps, sludge scrapers as 
common in all current art systems. In the described apparatus there is no 
equipment or parts that can fail and therefore the apparatus and the 
associated treatment is exceptionally reliable substantially requiring no 
supervision or maintenance. Because of the simplicity of the invented 
apparatus the capital and operating costs for the described biological 
treatment are considerably lower than the costs of all current art 
systems. 
It is also apparent that if further treatment of the clarified effluent is 
required such can be provided by the existing tertiary treatments. 
Having described the preferred embodiment of my invention, it should be 
apparent to those skilled in the art that the same permits modification in 
arrangement and detail. I claim as my invention all such modifications as 
come within the true spirit and scope of the following claims.