Liquid purification or separation – Processes – Treatment by living organism
Reexamination Certificate
1998-06-16
2001-05-29
Barry, Chester T. (Department: 1724)
Liquid purification or separation
Processes
Treatment by living organism
C210S609000, C210S620000, C210S631000, C210S705000
Reexamination Certificate
active
06238564
ABSTRACT:
DETAILED DESCRIPTION OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to a sludge treatment method. In accordance with the present invention, the bulking phenomenon having been a taboo conventionally in the industry is conversely utilized, on the basis of an absolutely novel idea.
More specifically, the present invention relates to a sludge treatment method, characterized in that
(1) for concentrating excess sludge and the like, the sludge and the like are never precipitated or concentrated through the addition of coagulants and the like as carried out conventionally but the sludge is on contrast adsorbed on carbide to coagulate the sludge and additionally, the coagulated matter of coagulated sludge is floated up by means of gas generated through biological actions in the sludge to intend to separate the sludge from treated water, thereby attaining the recycling of sludge;
(2) the water in the coagulated matter is reduced to make sludge treatment more readily carried out; and
(3) the occurrence of smell during coagulation and separation is further prevented,
and the present invention relates to
(4) a method for producing compost by utilizing Actinomycetes as a means of recycling of sludge floated up and separated in such manner.
2. Prior Art
Liquid waste disposal essentially involves the generation of sludge. So as to finally dispose the sludge, for example so as to incinerate the sludge, treatments such as dehydration and drying are required.
Generally, the water content in sludge generated via precipitation and separation is 98% or more, and because the water content is so high, sludge should necessarily be dehydrated for final disposal.
As a preliminary treatment of dehydration, conventionally, a method has been known, comprising adding a coagulant into a sludge mixture solution and precipitating and concentrating the solution, and the method has been practiced at disposal plants at large scales, such as night soil treatment plants, sewage treatment plants or food plants.
Furthermore, excess sludge at small scale purifying facilities at small companies and private houses is wholly brought into sewage treatment plants at large scales, where the same treatment as described above is effected.
According to the conventional methods as described above, it is required that sludge has good precipitability enough to be separated readily from treated water in sedimentation tanks, and if a bulking (expansion) phenomenon, ie. abnormal sludge floating up phenomenon occurs, the precipitability is extremely deteriorated; if SVI (sludge volume index) is 200 or more, for example, the separation in sedimentation tanks is deteriorated, to finally cause that the treatment cannot be continued.
According to the conventional methods, therefore, the floating up of sludge is an abnormal phenomenon, and the floating up of sludge means that the treatment cannot be continued any more, so the floating up of sludge is a taboo and the prevention thereof is inevitable.
In accordance with the present invention, meanwhile, the floating up of sludge is actively utilized, so the conventional state of art is broken through, and thus, the present invention is truly innovative.
PROBLEMS THAT THE INVENTION IS TO SOLVE
The method for precipitation and concentration, having been carried out conventionally, comprises adding coagulants such as aluminium and calcium salts and the like to a sludge mixture solution, thereby coagulating sludge in the sludge mixture solution and separating the sludge, and therefore, the separated coagulated matters contain salts and the like. When the separated coagulated matters are back to cultivating fields of rice or vegetable, therefore, damages due to high concentrations of salts may occur; or the coagulated matters cannot be prepared as compost because the matters contain components hazardous to plants, and as described above, the recycling has been limited.
Hence, the separated sludge mostly has to be dried and then incinerated and dumped, but even in this case, the occurrence of secondary pollution due to the remaining salts and the like cannot be avoided and the difficulty in selecting dumping sites and the escalation of the running cost following the site selection are problematic.
The present invention has been attained with the objects of overcoming these problems.
REFERENCES:
patent: 3876536 (1975-04-01), Pradt et al.
patent: 4168228 (1979-09-01), Mallatt et al.
patent: 4292176 (1981-09-01), Grutsch et al.
patent: 4407717 (1983-10-01), Teletzke et al.
patent: 5804076 (1998-09-01), Yamasaki et al.
patent: 5876613 (1999-03-01), Bonnin et al.
Asahi Newspaper of Dec. 6, 1997, p. 3 Japan.
Barry Chester T.
Browdy and Neimark
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