Process and system for treatment of pig and swine manure for environmental enhancement

A low cost efficient method and system for treating animal waste and in particular pig and swine solid and liquid manure to allow removable of undesirable odors and return of sludge and liquid safely to the environment to eliminate or reduce pollution. The method and system include collecting the manure into a central tank and using a continuous process to compress the manure to separate liquid from the solid sludge and transferring the separated liquid to a separate holding tank. The dried out sludge is collected as a residual and can be safely returned to the environment. Calcium carbonate may be added to the residual sludge to reduce odor. A polymer may be added to the pressing stage of the sludge to enhance liquid sludge separation. The separated liquid is then treated with a pressure filter membrane to remove undesirable elements from the liquid after which is filtered and is returned safely to the environment either to a natural stream to a sewage system or for agricultural uses.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to a process and system to treat domestic 
animal manure, such as pigs and swine, both liquid and solid, to enhance 
the environment so that the residual treated solid and liquid waste are 
free from odors, can be returned back to the environment, and can be used 
as productive elements of the environment and, specifically, to a process 
and system that treats pig and swine liquid and solid manure to eliminate 
odors, water contamination, and soil contamination, with the safe return 
of these byproducts back into the environment at low cost. 
2. Description of the Prior Art 
The creation of large farms for raising domestic animals at the commercial 
level in large numbers, such as cows, chickens, pigs, and swine, has 
created an increased concern environmentally over the animal waste 
products, typically liquid and solids, created by such large domestic 
production of animals. Typical environmental concerns which are each 
related but different in result include air contamination caused by the 
odors produced from the waste, ground water and stream contamination from 
runoffs at the waste site, and soil contamination, particularly for 
agricultural purposes, resulting from the large volume of waste. 
Therefore, organic animal waste sludges have become a tremendous 
environmental problem throughout the United States and throughout the 
world. 
The prior art discloses processes for trying to solve the problem of sludge 
and the environment. U.S. Pat. No.: 4,193,206 issued Mar. 18, 1980 to 
Maffet discloses processes for drying sewage sludge and filtering water. 
As shown, wet sewage sludge is dried in either a thermal drying zone or a 
mechanical dewatering zone comprising a cylindrical chamber with a porous 
wall. A plasticizer is added to the dry sludge. Overall, the system is 
rather complicated and has several additional processes when compared with 
applicant's invention. U.S. Pat. No.: 4,270,279 issued Jun. 2, 1981 to 
Roediger discloses a method for drying, and sterilizing sewage sludge. 
Basically the sludge is dried and broken into small pieces and covered 
with quicklime. U.S. Pat. No.: 4,295,972 issued Oct. 20, 1981 to Kamei 
discloses a method for treating water containing waste. The method 
includes adding calcium oxide for preliminary drying and granulating the 
mixture. U.S. Pat. No. 5,013,458 issued May 7, 1991 to Christy, Sr. et al. 
discloses a process and apparatus for pathogene reduction and waste. The 
method includes using hydration reaction by elevating the pH of the sludge 
for releasing heat. None of the methods disclosed in these patents shows 
the simple and efficient treatment of sludge as disclosed by applicant's 
method which includes economical steps of dewatering the sludge and water 
filtration using membranes. 
Thus, when looking at agricultural waste, the increasing production of the 
waste, such as pig and swine production and their waste products, presents 
a large problem for both farming soils and the natural environment, which 
includes streams, water tables, and soils. 
Although this specific invention is directed toward pig and swine liquid 
and solid manure waste products for the treatment of odor, and liquid and 
solid waste contamination, the invention may have other applications for 
the treatment of agricultural, industrial, and municipal sludges also. 
The overall invention, both the method and system, deals with two major 
phases. Phase one involves the separation of liquids from the sludge or 
animal waste product, be it pig manure or swine manure, to get the driest 
sludge available, while separating the water for further treatment. This 
greatly reduces the volume of the sludge from the first phase once a good 
portion of the liquid has been removed. 
The second phase involves the treatment of water and liquid removed from 
the pig and swine waste sludge. This water is treated by a pressure-driven 
membrane separation technology so that it is clean enough environmentally 
to return to the natural water supply. One of the important features of 
the invention is that it limits the use of additional chemicals that have 
been traditionally used to treat sludge to further prevent environmental 
harm. Thus, the invention does not use chemicals, such as chlorine, to 
accomplish the results. 
SUMMARY OF THE INVENTION 
In the first step of the operation, pig liquid manure and swine waste, 
solid and liquid, are collected at a common location for treatment. In the 
present environment in many states of the United States, the pig and swine 
waste may be collected into a sludge lake much like a holding pond or tank 
that provides some evaporation. In any event, the materials can be 
collected in a single place or transported to an area where the first step 
of the invention will be performed. In one embodiment, a rotary press for 
sludge is utilized. The purpose of step one is to remove as much water and 
liquid from the swine and pig waste sludge materials so that the liquid is 
completely removed, leaving a solid cake-like material. Using a rotary 
press for sludge, concentrations in the 30 percent solids can be obtained. 
Thus, the liquid-laden sludge is fed into the rotary press on a continuous 
basis, allowing for continuous operation of the removal of the wastewater 
and separation of wastewater from the original sludge materials. To 
enhance the solid/liquid separation, polymers may be added to the sludge 
for improved liquid separation. 
The water and liquids being removed from the sludge are collected and 
stored in a holding tank for the second step of the process. The waste 
water must be treated because the contaminants in the separated water are 
too high for direct discharge into the environment. 
The rotary pressing of the sludge is desired because the process is 
continuous and, unlike batch processing, does not have to wait for 
sedimentation or decantination to occur. Typically, a rotary press needs a 
small physical space and can be either a mobile unit or a fixed unit, 
depending on the environment it is to be used in. 
The second step used by the process treats the waste liquid (water) that 
results from pressing the sludge, which is substantially water having low 
suspended solids and other contaminants that cannot be directly discharged 
into the environment, either into a sewer or into the natural environment. 
The system used to accomplish the treatment of water for improving its 
environmental quality is nanofiltration and/or reverse osmosis. The 
purpose of nanofiltration and reverse osmosis is to separate residual 
contaminants remaining in the water, resulting in two different streams. 
The wastewater for treatment is fed using tangential flow direction to the 
separating membrane. Separation occurs using pressure force to the feed. 
The inlet stream is called the "concentrate" because it contains and 
continues to have the contaminants that cannot pass through the membrane. 
The treated water in the second stream is called a "permeate" and 
basically consists of water and some salts that pass through the membrane. 
The permeate is the final product of the entire process and system, which 
can be directly transferred into the environment, either into existing 
streams, naturally occurring underground water, or into an existing sewer 
system. 
The concentrated stream of the membrane system can be recycled into the 
feed inlet of the first step or it can be added to the thickened sludges 
if the solid content is sufficiently high. For agricultural waste, the 
concentrate is rich in nitrogen components. Many of the nitrogen 
components are soluble and usually pass through the liquid separation 
phase. 
In a final step, calcium carbonate may be added to help neutralize the pH 
of the resultant sludge and prevent the formation of malodorous compounds, 
reducing bad odors. 
The process described herein for treating pig and swine waste has many 
advantages. First, it greatly reduces the large volume of sludge and 
results in a sludge product that can be transferred into the environment 
without malodorous odors typically emanated by sludges, especially 
agricultural waste such as liquid manure from pig houses. Typically, 
malodorous odors are generated by storage of wet sludge in huge volume 
tanks. 
The method and system also provide for the environmental improvement of the 
liquid waste or water that can now be safely returned to the environment, 
both for agricultural purposes or returned naturally to streams or into 
sewer systems. 
In an alternative embodiment of the invention a method and system are 
employed where the solid/liquid separation is a partial dehydration system 
that uses flocculation and decantination. In this embodiment the sludges 
in step one, which are swine waste and pig waste, are fed through a 
conical tank. A polymer must be added to the sludges to permit coagulation 
and flocculation to occur. The polymer reacts with solids to form a 
cake-like material and the water is evacuated by gravity at the base of 
the inverted cone. This process may be operated in a batch mode during a 
12-hour cycle approximately. The free water is continuously evacuated from 
the conical tank and can be stored in a separate tank before it achieves 
the second treatment step. The system does not need very much volume and 
can also be delivered in a fixed or mobile unit, depending on the 
particular needs. This technology is commercially available in Canada by 
Valoration, Holbrothe, Quebec. 
When the sludge has thickened, it is removed from the conical tank. The 
concentration of sludges is usually higher than 20 percent solids. The 
removed sludges can then be stored for agricultural spreading or used for 
composting. During storage, it is recommended to add calcium carbonate 
(C.sub.a CO.sub.3) to the sludges for stabilization, pH reduction, and 
retention of nitrogen components. Calcium carbonate reacts with malodorous 
volatile components, such as hydrogen sulfur, to form salts. This chemical 
prevents undesirable odors from emanating from the sludges. 
Other technologies may be used for solid/liquid separation for step one 
which may include screening microfiltration, ultrafiltration, and 
decantination. Microfiltration or ultrafiltration can be used in 
complement with another liquid/solid separation technology like the rotary 
press, to improve the quality of the liquid that goes to the second phase. 
With respect to treatment of the liquid or water stream that results from 
the sludge separation, the water may be treated with other technologies 
such as ion exchange or chemical precipitation. The advantage of the 
membranes is that it can be continuous and other chemical are not involved 
for enhancing the quality of the water for return to the environment 
safely. 
Another advantage is that the process, which is very economical and mobile, 
can be automated. 
It is an object of this invention to provide an improved method and system 
for treating pig and swine waste products, such as manure and liquid 
manure, economically to provide an environmentally safe residue that can 
be returned to the environment. 
It is another object of this invention to provide an improved process for 
economically treating food, agricultural, and municipal treatment sludges, 
including animal waste such as pig and swine manure, solid and liquid, in 
order to economically remove odors, to reduce the volume of the sludge, 
and to provide both a treated sludge and water that can be safely returned 
to the environment in an economical manner. 
But yet still another object of this invention is to provide an economical 
process and system for managing agricultural sludges such as liquid 
manure, to reduce air contamination, especially odors, water contamination 
such as streams and water tables and municipal water supplies, and 
agricultural soil contamination economically and safely, without the use 
of harsh chemicals. 
In accordance with these and other objects which will become apparent 
hereinafter, the instant invention will now be described with particular 
reference to the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings and in particular FIG. 1, the method of the 
invention is shown in a flow chart. The first step of the invention (which 
can be automated as a function of volume to treat) is to collect the pig 
and swine liquid and solid manure into some type of holding container or 
holding pond, shown in step 10. The next step 12 is to transfer liquid and 
solid manure to a sludge mechanical press, preferably one with a 
continuous process, where the liquid is removed from the sludge. The 
pressing step 12 is done and may include adding a polymer 14 as a step to 
enhance the drying process. After the sludge is pressed, separation 
between the liquid and sludge takes place from the press and the liquid is 
transferred to a holding tank 18. The remaining sludge is then collected 
as residual sludge 20. This step calcium carbonate (C.sub.a CO.sub.3) may 
be added to raise the pH to eliminate odors. After that is done (which is 
optional), the sludge is then returned to the environment safely 28. 
The liquid that was transferred in step 18 to the holding tank then is 
filtered through a membrane 22 to remove undesirable pollutants in the 
water. Any residue that does not pass through the membrane may be returned 
to the separation of the liquid and sludge in the press. Once the filtered 
water is passed through the membrane in step 22, the water may be safely 
returned to the environment 24 as the final step in the process. 
As can be understood from the process, it is economical, efficient because 
it is continuous and allows for treating large amounts of sludge quickly 
and efficiently. FIG. 2 shows a schematic diagram of the method shown in 
FIG. 1. Specifically, the raw pig or swine sludge is deposited in a 
storage tank. From the storage tank a pump 32 pumps the sludge into a 
press 34 called a solid liquid separator. The continuous press 34 thus 
acts to squeeze out in a continuous process excess water that is retained 
in the sludge such that the water is pumped from one area of the press to 
a separate water storage tank 34. Simultaneously, the thickened sludge 
that has water removed itself is a continuous process that can be 
transferred to a conduit 46 into a separate storage tank 48 that contains 
the thickened sludge. This sludge is ready to be placed into the 
environment. 
The storage tank containing the water 34 then allows the water to be pumped 
by pump 38 to the membrane separation 40 which is a tank with a membrane 
of water coming in one side that allows the filtered water to pass through 
the membrane and out through conduit 42 where it can be returned to the 
environment to sewer or to streams or for agricultural use for watering. 
Any of the materials that were not passed through the membrane can be 
returned through conduit 44 through the first storage tank to be treated 
over or to the storage of the thick and sludge. 
Thus, the sludge that has been dried out in which odors have been removed 
is thus suitable for return to the natural environment safely and 
efficiently. Likewise, the water that has been passed through the membrane 
is itself safe enough to be returned to a natural environment or to a 
sewage system. 
In an alternate embodiment, the solid/liquid separation could be 
accomplished using partial dehydration, flocculation and decantination 
wherein the sludges are fed to a conical tank that is inverted. A polymer 
must be added to the sludge to permit coagulation and flocculation to 
occur. The polymer reacts with solids to form a cake like material wherein 
the water would be evacuated by gravity. This process is operated in a 
batch mode during 12 hour cycles approximately. The free water would be 
continuously evacuated from the conical tank during the process and can be 
stored in a tank before the second treatment step. 
When the thickening of the sludge is complete, the sludge is removed from 
the conical tank and can be stored for agricultural spreading or 
composting. Calcium carbonate (C.sub.a CO.sub.3) should be added to the 
sludge to stabilize and to and to retain nitrogen components. The calcium 
carbonate also reacts with malodorous volatile components like hydrogen 
sulfur to form salt. This chemical prevents the malodorous odors. Solid 
liquids separation could also be accomplished from screening and 
microfiltration, ultrafiltration, or decantination. Microfiltration or 
ultrafiltration can be used in combination with screening or rotary 
pressing. However, the rotary continuous press described in here is the 
preferred embodiment. 
As described as to the liquid treatment by pressure driven membranes 
separation technology. Nanofiltration and or reverse osmosis used to 
separate residual contaminants in the water as described in FIG. 1 method 
and FIG. 2 which produces two different streams. They are fed using a 
tangible flow direction to the membrane. The separation occurs using 
pressure force to the feed. The first stream is called concentrate because 
it contains the contaminants rejected by the membrane. A second stream is 
called the permeate and it contains water and salt that pass through the 
membrane. The permeate is the final product of the process that can be 
directly rejected to the environment. In alternative embodiment, the water 
could be treated with an iron exchange or chemical precipitation to 
prepare it for return to the environment. The concentrate stream if 
necessary can be returned to the first step feed or added to the thick and 
sludge if the content is sufficiently high. The separated liquid (water) 
could additionally be subjected to electropotentials (anode and cathode) 
to remove metallic ions such as Z.sub.n.sup.2+ ions and chromium ions. 
FIG. 3 shows the method and flow chart of the alternative embodiment of the 
invention. 
FIG. 4 shows a rotary press that can be used on a continuous basis to 
separate liquid and water from the sludge leaving a dry cake sludge. The 
sludge is fed into a peripheral channel and has walls made up of filter 
elements which allow the liquid to pass through while retaining the solid. 
The wheel as it moves generates a compressive and driving force on the 
sludge cake which is formed. The compressive force coupled with a minimum 
inlet pressure and outlet restrictive action results in a cake whose level 
of dryness is high. As the sludge is continuously fed into the device, the 
cake extrusion is continuously fed out of the device while at the same 
time the water is continuously being removed by the compressive forces. As 
an example, a Fournier rotary press for dewatering located in Blacklake 
Quebec, Canada could be utilized. 
The use of the above described invention has many advantages. First of all, 
it permits reduction of pig and swine waste sludge volume to give a final 
product that can be disposed safely into the environment at low cost. The 
process also minimizes undesirable odors that eminent from the sludge 
particularly with a pig manure generated by the large pig farms currently 
found throughout the United States. Also large amounts of water removed 
from the sludge can be safely returned directly into a stream and existing 
sewage system or can be agriculturally for water. 
The instant invention has been shown and described herein in what is 
considered to be the most practical and preferred embodiment. It is 
recognized, however, that departures may be made therefrom within the 
scope of the invention and that obvious modifications will occur to a 
person skilled in the art.