CA1054896A - Process for removing and recovering precipitation agents from precipitate containing proteinous substances - Google Patents
Process for removing and recovering precipitation agents from precipitate containing proteinous substancesInfo
- Publication number
- CA1054896A CA1054896A CA232,085A CA232085A CA1054896A CA 1054896 A CA1054896 A CA 1054896A CA 232085 A CA232085 A CA 232085A CA 1054896 A CA1054896 A CA 1054896A
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- Canada
- Prior art keywords
- precipitation
- precipitation agent
- protein
- process according
- centrifugate
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23J—PROTEIN COMPOSITIONS FOR FOODSTUFFS; WORKING-UP PROTEINS FOR FOODSTUFFS; PHOSPHATIDE COMPOSITIONS FOR FOODSTUFFS
- A23J1/00—Obtaining protein compositions for foodstuffs; Bulk opening of eggs and separation of yolks from whites
- A23J1/001—Obtaining protein compositions for foodstuffs; Bulk opening of eggs and separation of yolks from whites from waste materials, e.g. kitchen waste
- A23J1/002—Obtaining protein compositions for foodstuffs; Bulk opening of eggs and separation of yolks from whites from waste materials, e.g. kitchen waste from animal waste materials
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- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Hydrology & Water Resources (AREA)
- Water Supply & Treatment (AREA)
- Food Science & Technology (AREA)
- Polymers & Plastics (AREA)
- Inorganic Chemistry (AREA)
- Zoology (AREA)
- Environmental & Geological Engineering (AREA)
- Biochemistry (AREA)
- Organic Chemistry (AREA)
- Separation Of Suspended Particles By Flocculating Agents (AREA)
- Treatment Of Sludge (AREA)
- Peptides Or Proteins (AREA)
- Pigments, Carbon Blacks, Or Wood Stains (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
- Removal Of Specific Substances (AREA)
Abstract
ABSTRACT
This invention relates to a process for removing and recovering a precipitation agent, such as lignin sulphonic acids, from a precipitated material containing protein. Known techniques for recovering protein from effluents such as slaughterhouse process water result in a protein recovery which is relatively high in precipitation agent content.
Protein recovery according to this invention is upgraded by adding sufficient alkaline earth compounds, for example calcium chloride, to the precipitate so as to be able to form an alkali metal proteinate and where necessary, sufficient alkali hydroxide such as sodium hydroxide to neutralize same.
The mixture is then heated to coagulate the proteinate so formed and to recover the hydrous precipitation agent so produced. The recovered precipitation may then be advantageously again used as a precipitation agent.
This invention relates to a process for removing and recovering a precipitation agent, such as lignin sulphonic acids, from a precipitated material containing protein. Known techniques for recovering protein from effluents such as slaughterhouse process water result in a protein recovery which is relatively high in precipitation agent content.
Protein recovery according to this invention is upgraded by adding sufficient alkaline earth compounds, for example calcium chloride, to the precipitate so as to be able to form an alkali metal proteinate and where necessary, sufficient alkali hydroxide such as sodium hydroxide to neutralize same.
The mixture is then heated to coagulate the proteinate so formed and to recover the hydrous precipitation agent so produced. The recovered precipitation may then be advantageously again used as a precipitation agent.
Description
It is well known that a number of substances can be used as precipitation agents on an industrial scale to remove proteins from effluents such as process water. The principal groùp of precipitation agents in use is probably the lignin sulphonic acids and their derivatives. A number of installations based on the use of lignin sulphonic acids have been built in many contries and these installations are employed to purify industrial effluents while recovering a substantial quantity of the proteins, see US Patent No. 3 390 999. Other organic lo substances that have been used as precipitation agents are organic sulphonates, such as aryl or aryl alkyl sulphonic acids, as described in Canadian Patent No. 882 398, and organic sulphates, such as sulphuric acid esters of monovalent and polyvalent alcohols, such as lauryl sulphate, glyceryltrisulphate and sulphated hexavalent alcohols and sulphated hexavalent carbohydrates, reference here being made to Norwegian Patent No. 117 339 and Canadian Patent No. 887 899. Most of these organic sulphonic acids and sulphates have a very good puri-fying effect, but to use them for purifying water on an industrial scale involves relatively high costs for chemicals. It is further known that proteins precipitated by means of the said agents can be used as fodder. It would, however, be an advantage if it were possible to lessen the content of said precipitation agents. By reducing the amount of precipitation agents in the precipitate, one would be able at the same time to increase the protein content and thus the commercial value of the materials as fodder.
In the known methods for precipitating proteins, proteins, especially from industrial effluents, the precipitate is separated from the hydrous phase by some mechanical method, 1~54896 e.g. flotation, which gives a sludge containing ~etween 5 and 15% solids.
This sludge must often be further concentrated before final treatment. Concentration can be done by filtering or by centrifugation, after pre-treatment by e.g. heat and/or the ad-dition of calcium in a manner known per se, e.g as described in Australian Patent No. 478,968. This appears to be a comparatively effective method of concentration, but the greater part of the precipitation chemicals remain in the sludge phase, while a dis-proportionately large amount of the proteins pass into the hydrousphase.
The process according to the present invention consists in that an alkaline earth compound is added to the protein sludge and, if necessary, an al~aline or alkaline earth hydroxide is added until a pH of about 7 - 9 is obtained, followed by heating, during which the protein complex present in the precipitation agents and proteins splits, whereupon the proteins coagulate as an alkaline earth proteinate and the precipitation agent dissol-ves in the sepa~ated hydrous phase. By washing out the coagulated material, it is moreover possible to recover the precipitation agents almost quantitavely. If alkaline earth hydroxide, e.g.
Ca(OH)2, is used alone before the protein sludge is heated, a smaller proportion of the precipitation agent is dissolved and consequently less precipitation agent is recovered, probably be-cause the calcium salts of the said precipitation agents are less soluble. One advantage of calcium alone is, however, that the coagulated material has a firmer consistency and separates better, it is,'`for example, easier to filter.
The present invention provides a process for the remo-val and recovery of precipitation agent from precipitated materialcontaining proteins, characterized in that alkaline earth com-pounds are added to the precipitated material in quantities suf-~54896 ficient to bind the proteins and if after such addition the pH
number is still below 6.5, a base in the form of alkaline hydro-xide is added to produce a pH number higher than 6.5, whereafter the material is heated to a temperature above the coagulation point of the proteins present, thereby separating the precipita-tion agent which is removed whereafter it can again be used for precipitating proteins.
By using an alkaline earth salt in a quantity 1~)54896 sufficient to form alkaline earth proteinate and alkali hydroxide, adequate for neutralization, the precipitation agent will dissolve as alkaline salt that is highly soluble and thus make it possible to recover the precipitation agent almost quantitatively.
The sludge used for the experiment was ligno-protein sludge separated by precipitation of proteins in slaughterhouse Lo effluents with 14.5% solids.
The sludge had a pH of 4.1 and calcium was added to raise the pH to 8.o. The sludge was then heated to a temperature of 95C, at which temperature the sludge coagulated. After a suitable interval and reaction time, centrifugation of L5 the sludge Was carried out and the centrifugate was thereafter used as precipitation agent for a protein solution for which the optimal dosage of pure ligno-sulphonic acid was known.
A certain quantity of the centrifugate was added to the protein solution together with varying quantities of ligno-sulphonic ~o acid. The protein material in the solution was precipitated and organic substance was measured in the resulting decantate by determining COD.
Slaughterhouse effluents of the same quality as used to precipitate the ligno-protein sludge being examined, was used Z5 as protein solution for the recovery test.
The result of the experiment are shown in the following table.
l(~S4896 TABLE FOR EXAMPLE I
___ Dosage (for 500 ml protein ~
_ sc lution) _ COD in % COD
Lignosul- Sulphuric Centrifu- decan- tion Line No.
phonate acid gate mg/l mg/l ml mg o2/1 O 600 O 3886 17.14 O 700 5 1259 73.15 ll ll 1178 74.89 100 ll .. 1189 74.64 150 ll ll 1239 73.59 200 ll ll 1276 72,79 250 ll ll 1300 72.29 _ O 600 O 3886 17.14 O 700 5 1259 73.15 2 O ll 10 1341 71.41 O ll 15 1706 63.64 _ 250 600 O 1036 77.91 300 ll O 1016 78.34 3 350 ll O 1022 78.20 400 ll O 1075 77.o7 The table and lines clearly show that the centrifugate contains a large quantity of recovered precipitation agent.
Precipitation of protein solution with centrifugate alone gave the best result when 5 ml centrifugate was added to 500 ml protein solution. In this case COD reduction is 73,5% as against 1~54896 17.14% when only sulphuric acid was added. Line 2 shows that the optimal quantity of centrifugate for precipitation of protein solution should be about 8 ml per 500 ml, whereby one would obtain a COD number in the decantate of about l.l9o mg 5 ~ 02/1, corresponding to a COD reduction of about 74.6%. Comparing this with the extrapolated part of line 3, it should be possible to set the quantity of recovered precipitation agent as being equivalent to a dosage of about 175 mg/l or about 87 mg/Soo ml. This means that the concentration of precipitation lo agent in the centrifugate should be approx. 87 mg/ml or approx.
lo g/l.
Line 1 shows that the optimal dosage of ligno-sulphonate in addition to S ml centrifugate per Soo ml is about 70 mg/l.
If more ligno-sulphonate is added, precipitation of protein solution will be less effective owing to overdosage. This over-dosage effect can clearly be seen from line 3, which shows 300 mg/l as the optimal ligno-sulphonate dosage. As COD
reduction is not improved by adding more than about 70 mg/l ligno-sulphonate in addition to S ml centrifugate (see line 1), one can assume that recovered precipitation agent in the centrifugate is equivalent to a dosage of about 300 - 70 =
230 mg/l, or approx. 115 mg per 500 ml. sased on this assumption, the centri~ugate added contains 115 mg/ml or approx. 20 g/l.
EXAMPLE II
A certain quantity of calcium chloride was added to the same sludge as used for Example I, followed by the use of sodium hydroxide to adjust pH to 8.o. The sludge was then heated to 95C, when coagulation occurred, and after a suitable interval and reaction time at this temperature the specimen was subjected 1~54896 to centrifugation. The centrifugate was analyzed ana used as a source for ligno-sulphonate by adding a cer~ain quantity to a protein solution and whereupon varying quantities of ligno-sulphonic acid were added. Unexpectedly it proved that better precipitation of the proteins was achieved by using this centrifugate as precipitation agent, so that the resulting hydrous phase was clear and clean. The hydrous phase of the specimens was analysed for COD to obtain an indication of the recovery of protein precipitation agent.
lo The results of the test are given in the following table.
TABLE FOR EXAMPLE II
_ Dosage (for 500 ml protein solution) COD in % COD Line No.
.
decan- reduc-Lignosul- Sulphuric Centri tatetion phonate acid fugat~
mg/l mg/l ml mg o2/1 O ~ O O 4690 O
O 600 O 3886 17.14 _ .
O 700 5 1126 75.99 " " 1084 76.88 100 " " 1117 76.18 4 150 " ll 1148 75.52 200 " ll 1173 74.98 250 " " 1210 74.20 _ .
O 700 5 1126 75.99 O " 10 1146 75.56 5 O " 15 1312 72.o2 The results from Example II can best be compared with the results from Example I by comparing line 4 (Ex.II ) with line l (Ex.I) and line 5 (Ex. II) with line 2 (Ex.I).
In relation to line l, line 4 shows that in Example II
a better COD reduction is obtained than in Example I and that the optimal dosage is somewhat lower than in Example I. This means that the centrifugate produced by coagulation with CaCl2 and NaOH contains more precipitation agent than in Example I.
This is further illustrated by comparing the results from lo the protein precipitation test with centrifugate alone. Line 5 (Ex. II) lies clearly below line 2 (Ex. I), which shows that the specific COD reduction is better with centrifugate from Ex.II. Furthermore, line 5 rises less than line 2 when the quantity of centrifugate exceeds the optimal dosage, which means that the proportion of substances without protein precipitating properties is less in the centrifugate from Example II than in that from Example I.
ExAMæLE III
Varying quantities of calcium were added to 3 specimens of the same sludge as used for Examples I and II, to obtain pH
numbers 7, 8 and 9 respectively before coagulation at 95C.
Centrifugation was carried out as in Example I and the centrifugates were examined as described in Examples I and II.
The results of the test are given in the following table.
1t354~96 TAB E FOR EXAMPLE III
pH when Dosage (for 500 ml protein COD in % COD Line coagu- solution) ___ _ decan- reduc- No.
lated Lignosul- Sulphu- Centri- tate tion phonate ric acid fugate mg/l mg/l ml mg o2/1 , 7....... O 700 5 1.372 70.74 8 O 700 5 1.259 73.16 6 9 O 700 5 1.168 75.09 7 50 700 5 1.265 73.02 8 50 700 5 1.178 74.88 7 9 50 700 5 1.143 75.62 i 7 100 700 5 1.225 73.88 8 100 700 5 1.189 74.64 8 9 100 700 5 1.202 74.37 Comparing the results here in the same way as in Examples I and II gives an indication of the dependence upon or significance of the pH for coagulation of the precipitated protein material.
Line 6, which shows the protein precipitation test with centrifugate alone, indicates a distinct improvement in precipitation effect for centrifugate from coagulation as the pH increases. Lines 7 and 8 with 50 and loo mg/l respectively of additional lignin sulphonate dosage show that an additional dosage of 50 mg/l to 5 ml centrifugate increases COD reduction as compared with centrifugate alone, but there is very little increase for the centrifugate from coagulation at pH 9. On the other hand, with an additional dosage of loo mg/l, the COD
reduction obtained with the centrifugate from coagulation at pH 9 is worse. Line 9 illustrates this, clearly showing that - 1~54896 the optimal additional lignin sulphonate dosage in addition to 5 ml centrifugate is approx. 50 mg/l. If this result is appraised in the same manner as in Example I, one can assume that the quantity of recovered precipitation agent in the centrifugate from coagulation at pH 9 is equivelent to a dosage of 300 - 50 =
, ~q 25o mg/l, or that the concentration of precipitation agent in the added centrifugate is 125 mg/l or 25 q/l, which is 25%
more than the concentration in the corresponding centrifugate from coagulation at pH 8 (Example I).
lo EXAMPLE IV
4 specimens each of loo grams of the same ligno-protein sludge as in Examples-I, II and III were coagulated at 95 C
after the addition of CaCl2 and NaOH to two specimens and Ca(OH)2 alone to two specimens, whereby pH was adjusted to 9.
Dehydration of the specimens was done in two different ways, so that one specimen conditioned by CaCl2 and NaOH and one specimen conditioned by Ca(OH)2 alone were subjected to centrifugation as in the preceding examples, while the two remaining specimens with different conditoning were filtered through a fibre-glass filter ~hatman GF/C and washed twice with 50 ml water. The quantities of centrifugate and filtrate were measured and the concentration of precipitation agent was determined by protein precipitation test as in the preceding examples.
1~54896 RESULTS
.
! Co~dition-~ ~Dehydra- Hydrous Precipitation agent ing tion phase yield %
method quantity Concentra- Recovered yield ml tion mg/ml mg .
CaC12 + Centri- 58 35 2.o30 66.6 NaOH fuge NaOH Filter 121 20 2.420 79.5 Ca(OH)2 Centri- 72 25 1. 800 59.1 Ca(OH)2 Filter 150 15 2.250 73.9 In addition filtration speed and volume yield were examined by using cold (15 C) and warm ~65C) water for washing out the coagulated material. Furthermore tests were carried out by adding cold water (15C) after coagulation and by stirring to cool the material before separation. These additonal tests showed as expected that filtration speed and yield volume ` are greatest when warm water is used for washing out the coagulated material, but by adding cold water and stirring before separation one obtained greater filtration speed and yield volume for the hydrous phase. Cooling the material to about 50C before separation therefore appears advantageous.
The yield volumes for centrifugation and filtration show that separability is best for sludge conditioned by Ca(OH)2 alone, while the precipitation agent yield shows that conditioning with CaC12 and NaOH before coagulation gives best recovery of precipitation agent from the protein material.
According to the consumption of lignin sulphonate for ,.
producing the sludge and according to residue analysis of 1~354~396 lignin sulphonate in the effluents treated, the ligno-protein sludge containing 14,5% solids, contains in the solids 21%
lignin sulphonate, which is equivalent to 14.5 x o.21 = 3.o45 mg lignin sulphonate in loo g sludge. As the table shows, for coagulated sludge conditioned by CaC12 + NaOH or by Ca(OH)2 alone, the recovered yield of precipitation agent can by washing be increased from 66.6 to 79.5/0 and 59.1 to 73.9/0 respectively by washing out with water.
lo EXAMPLE V
To examine the possibility of removing other precipitation agents from precipitated protein material, different types of protein sludge were produced by precipitation of effluents containing proteins, using the following precipitation agents:
~auryl sulphate Glyceryl trisulphate Dodesyl-benzene-sulphonic acid Aluminium sulphate The same slaughterhouse effluents were used, with COD = 4.590 mg 0/1, as for the production of ligno-protein sludge in the four preceding examples. Paral}el tests were carried out with effluents from destructive plant for slaughterhouse waste (production of meat-bone meal and technical fats) and with diluted blood water from pig slaughtering.
The separated sludge was brought to pH 9 by the addition of Ca(OH)2, coagulated at 95 C, and centrifugation was carried out. The centrifugates from the different types of sludge were subjected to the same protein precipitation tests as the preceding examples, 5, lo and 15 ml being used as precipitation 10548~6 agent for the same slaughterhouse effluents as described in the preceding examples. Sulphuric acid was added to obtain pH =
3 for all precipitations except precipitation of the centrifugate from the sludge precipitated by aluminium sulphate, for which the pH was adjusted to 6. The decantates from the protein precipitation tests were characterized by determining COD which served for calculating the amount of precipitation agent recovered.
RESULTS
Precipitation Dosage of COD in % COD Line , agent centrifu- decan- reduc-gate for tate tion ml mg o2/1 _ _ _ .
Lauryl sulphate 5 1.426 68,9 lo 1.172 74.5 lo 1.542 66.4 .
Glyceryl .
trisulphate 5 2.380 48.1 lo 1.438 68.7 11 . 15 1.567 65.8 Dodesyl- 5 2.135 53.5 benzene sulphonic lo 1.529 66.7 12 . . 15 1.813 34.o _ Aluminium 5 3.220 29.8 sulphate - lo 3.o72 33.o 13 3 o30 34.o _ .
~548~36 Compared with the results from Example I, line 2, one can see that the precipitation agent is removed from the precipi-tated protein material in the same way. For organic sulphonates and sulphates the degree of recovery is comparable, while it is substantially lower for aluminium sulphate.
Nevertheless it is obvious-that the method as claimed is generally applicable for removing precipitation agents from precipitated protein material in such a form that they can be re-used.
1~
In the known methods for precipitating proteins, proteins, especially from industrial effluents, the precipitate is separated from the hydrous phase by some mechanical method, 1~54896 e.g. flotation, which gives a sludge containing ~etween 5 and 15% solids.
This sludge must often be further concentrated before final treatment. Concentration can be done by filtering or by centrifugation, after pre-treatment by e.g. heat and/or the ad-dition of calcium in a manner known per se, e.g as described in Australian Patent No. 478,968. This appears to be a comparatively effective method of concentration, but the greater part of the precipitation chemicals remain in the sludge phase, while a dis-proportionately large amount of the proteins pass into the hydrousphase.
The process according to the present invention consists in that an alkaline earth compound is added to the protein sludge and, if necessary, an al~aline or alkaline earth hydroxide is added until a pH of about 7 - 9 is obtained, followed by heating, during which the protein complex present in the precipitation agents and proteins splits, whereupon the proteins coagulate as an alkaline earth proteinate and the precipitation agent dissol-ves in the sepa~ated hydrous phase. By washing out the coagulated material, it is moreover possible to recover the precipitation agents almost quantitavely. If alkaline earth hydroxide, e.g.
Ca(OH)2, is used alone before the protein sludge is heated, a smaller proportion of the precipitation agent is dissolved and consequently less precipitation agent is recovered, probably be-cause the calcium salts of the said precipitation agents are less soluble. One advantage of calcium alone is, however, that the coagulated material has a firmer consistency and separates better, it is,'`for example, easier to filter.
The present invention provides a process for the remo-val and recovery of precipitation agent from precipitated materialcontaining proteins, characterized in that alkaline earth com-pounds are added to the precipitated material in quantities suf-~54896 ficient to bind the proteins and if after such addition the pH
number is still below 6.5, a base in the form of alkaline hydro-xide is added to produce a pH number higher than 6.5, whereafter the material is heated to a temperature above the coagulation point of the proteins present, thereby separating the precipita-tion agent which is removed whereafter it can again be used for precipitating proteins.
By using an alkaline earth salt in a quantity 1~)54896 sufficient to form alkaline earth proteinate and alkali hydroxide, adequate for neutralization, the precipitation agent will dissolve as alkaline salt that is highly soluble and thus make it possible to recover the precipitation agent almost quantitatively.
The sludge used for the experiment was ligno-protein sludge separated by precipitation of proteins in slaughterhouse Lo effluents with 14.5% solids.
The sludge had a pH of 4.1 and calcium was added to raise the pH to 8.o. The sludge was then heated to a temperature of 95C, at which temperature the sludge coagulated. After a suitable interval and reaction time, centrifugation of L5 the sludge Was carried out and the centrifugate was thereafter used as precipitation agent for a protein solution for which the optimal dosage of pure ligno-sulphonic acid was known.
A certain quantity of the centrifugate was added to the protein solution together with varying quantities of ligno-sulphonic ~o acid. The protein material in the solution was precipitated and organic substance was measured in the resulting decantate by determining COD.
Slaughterhouse effluents of the same quality as used to precipitate the ligno-protein sludge being examined, was used Z5 as protein solution for the recovery test.
The result of the experiment are shown in the following table.
l(~S4896 TABLE FOR EXAMPLE I
___ Dosage (for 500 ml protein ~
_ sc lution) _ COD in % COD
Lignosul- Sulphuric Centrifu- decan- tion Line No.
phonate acid gate mg/l mg/l ml mg o2/1 O 600 O 3886 17.14 O 700 5 1259 73.15 ll ll 1178 74.89 100 ll .. 1189 74.64 150 ll ll 1239 73.59 200 ll ll 1276 72,79 250 ll ll 1300 72.29 _ O 600 O 3886 17.14 O 700 5 1259 73.15 2 O ll 10 1341 71.41 O ll 15 1706 63.64 _ 250 600 O 1036 77.91 300 ll O 1016 78.34 3 350 ll O 1022 78.20 400 ll O 1075 77.o7 The table and lines clearly show that the centrifugate contains a large quantity of recovered precipitation agent.
Precipitation of protein solution with centrifugate alone gave the best result when 5 ml centrifugate was added to 500 ml protein solution. In this case COD reduction is 73,5% as against 1~54896 17.14% when only sulphuric acid was added. Line 2 shows that the optimal quantity of centrifugate for precipitation of protein solution should be about 8 ml per 500 ml, whereby one would obtain a COD number in the decantate of about l.l9o mg 5 ~ 02/1, corresponding to a COD reduction of about 74.6%. Comparing this with the extrapolated part of line 3, it should be possible to set the quantity of recovered precipitation agent as being equivalent to a dosage of about 175 mg/l or about 87 mg/Soo ml. This means that the concentration of precipitation lo agent in the centrifugate should be approx. 87 mg/ml or approx.
lo g/l.
Line 1 shows that the optimal dosage of ligno-sulphonate in addition to S ml centrifugate per Soo ml is about 70 mg/l.
If more ligno-sulphonate is added, precipitation of protein solution will be less effective owing to overdosage. This over-dosage effect can clearly be seen from line 3, which shows 300 mg/l as the optimal ligno-sulphonate dosage. As COD
reduction is not improved by adding more than about 70 mg/l ligno-sulphonate in addition to S ml centrifugate (see line 1), one can assume that recovered precipitation agent in the centrifugate is equivalent to a dosage of about 300 - 70 =
230 mg/l, or approx. 115 mg per 500 ml. sased on this assumption, the centri~ugate added contains 115 mg/ml or approx. 20 g/l.
EXAMPLE II
A certain quantity of calcium chloride was added to the same sludge as used for Example I, followed by the use of sodium hydroxide to adjust pH to 8.o. The sludge was then heated to 95C, when coagulation occurred, and after a suitable interval and reaction time at this temperature the specimen was subjected 1~54896 to centrifugation. The centrifugate was analyzed ana used as a source for ligno-sulphonate by adding a cer~ain quantity to a protein solution and whereupon varying quantities of ligno-sulphonic acid were added. Unexpectedly it proved that better precipitation of the proteins was achieved by using this centrifugate as precipitation agent, so that the resulting hydrous phase was clear and clean. The hydrous phase of the specimens was analysed for COD to obtain an indication of the recovery of protein precipitation agent.
lo The results of the test are given in the following table.
TABLE FOR EXAMPLE II
_ Dosage (for 500 ml protein solution) COD in % COD Line No.
.
decan- reduc-Lignosul- Sulphuric Centri tatetion phonate acid fugat~
mg/l mg/l ml mg o2/1 O ~ O O 4690 O
O 600 O 3886 17.14 _ .
O 700 5 1126 75.99 " " 1084 76.88 100 " " 1117 76.18 4 150 " ll 1148 75.52 200 " ll 1173 74.98 250 " " 1210 74.20 _ .
O 700 5 1126 75.99 O " 10 1146 75.56 5 O " 15 1312 72.o2 The results from Example II can best be compared with the results from Example I by comparing line 4 (Ex.II ) with line l (Ex.I) and line 5 (Ex. II) with line 2 (Ex.I).
In relation to line l, line 4 shows that in Example II
a better COD reduction is obtained than in Example I and that the optimal dosage is somewhat lower than in Example I. This means that the centrifugate produced by coagulation with CaCl2 and NaOH contains more precipitation agent than in Example I.
This is further illustrated by comparing the results from lo the protein precipitation test with centrifugate alone. Line 5 (Ex. II) lies clearly below line 2 (Ex. I), which shows that the specific COD reduction is better with centrifugate from Ex.II. Furthermore, line 5 rises less than line 2 when the quantity of centrifugate exceeds the optimal dosage, which means that the proportion of substances without protein precipitating properties is less in the centrifugate from Example II than in that from Example I.
ExAMæLE III
Varying quantities of calcium were added to 3 specimens of the same sludge as used for Examples I and II, to obtain pH
numbers 7, 8 and 9 respectively before coagulation at 95C.
Centrifugation was carried out as in Example I and the centrifugates were examined as described in Examples I and II.
The results of the test are given in the following table.
1t354~96 TAB E FOR EXAMPLE III
pH when Dosage (for 500 ml protein COD in % COD Line coagu- solution) ___ _ decan- reduc- No.
lated Lignosul- Sulphu- Centri- tate tion phonate ric acid fugate mg/l mg/l ml mg o2/1 , 7....... O 700 5 1.372 70.74 8 O 700 5 1.259 73.16 6 9 O 700 5 1.168 75.09 7 50 700 5 1.265 73.02 8 50 700 5 1.178 74.88 7 9 50 700 5 1.143 75.62 i 7 100 700 5 1.225 73.88 8 100 700 5 1.189 74.64 8 9 100 700 5 1.202 74.37 Comparing the results here in the same way as in Examples I and II gives an indication of the dependence upon or significance of the pH for coagulation of the precipitated protein material.
Line 6, which shows the protein precipitation test with centrifugate alone, indicates a distinct improvement in precipitation effect for centrifugate from coagulation as the pH increases. Lines 7 and 8 with 50 and loo mg/l respectively of additional lignin sulphonate dosage show that an additional dosage of 50 mg/l to 5 ml centrifugate increases COD reduction as compared with centrifugate alone, but there is very little increase for the centrifugate from coagulation at pH 9. On the other hand, with an additional dosage of loo mg/l, the COD
reduction obtained with the centrifugate from coagulation at pH 9 is worse. Line 9 illustrates this, clearly showing that - 1~54896 the optimal additional lignin sulphonate dosage in addition to 5 ml centrifugate is approx. 50 mg/l. If this result is appraised in the same manner as in Example I, one can assume that the quantity of recovered precipitation agent in the centrifugate from coagulation at pH 9 is equivelent to a dosage of 300 - 50 =
, ~q 25o mg/l, or that the concentration of precipitation agent in the added centrifugate is 125 mg/l or 25 q/l, which is 25%
more than the concentration in the corresponding centrifugate from coagulation at pH 8 (Example I).
lo EXAMPLE IV
4 specimens each of loo grams of the same ligno-protein sludge as in Examples-I, II and III were coagulated at 95 C
after the addition of CaCl2 and NaOH to two specimens and Ca(OH)2 alone to two specimens, whereby pH was adjusted to 9.
Dehydration of the specimens was done in two different ways, so that one specimen conditioned by CaCl2 and NaOH and one specimen conditioned by Ca(OH)2 alone were subjected to centrifugation as in the preceding examples, while the two remaining specimens with different conditoning were filtered through a fibre-glass filter ~hatman GF/C and washed twice with 50 ml water. The quantities of centrifugate and filtrate were measured and the concentration of precipitation agent was determined by protein precipitation test as in the preceding examples.
1~54896 RESULTS
.
! Co~dition-~ ~Dehydra- Hydrous Precipitation agent ing tion phase yield %
method quantity Concentra- Recovered yield ml tion mg/ml mg .
CaC12 + Centri- 58 35 2.o30 66.6 NaOH fuge NaOH Filter 121 20 2.420 79.5 Ca(OH)2 Centri- 72 25 1. 800 59.1 Ca(OH)2 Filter 150 15 2.250 73.9 In addition filtration speed and volume yield were examined by using cold (15 C) and warm ~65C) water for washing out the coagulated material. Furthermore tests were carried out by adding cold water (15C) after coagulation and by stirring to cool the material before separation. These additonal tests showed as expected that filtration speed and yield volume ` are greatest when warm water is used for washing out the coagulated material, but by adding cold water and stirring before separation one obtained greater filtration speed and yield volume for the hydrous phase. Cooling the material to about 50C before separation therefore appears advantageous.
The yield volumes for centrifugation and filtration show that separability is best for sludge conditioned by Ca(OH)2 alone, while the precipitation agent yield shows that conditioning with CaC12 and NaOH before coagulation gives best recovery of precipitation agent from the protein material.
According to the consumption of lignin sulphonate for ,.
producing the sludge and according to residue analysis of 1~354~396 lignin sulphonate in the effluents treated, the ligno-protein sludge containing 14,5% solids, contains in the solids 21%
lignin sulphonate, which is equivalent to 14.5 x o.21 = 3.o45 mg lignin sulphonate in loo g sludge. As the table shows, for coagulated sludge conditioned by CaC12 + NaOH or by Ca(OH)2 alone, the recovered yield of precipitation agent can by washing be increased from 66.6 to 79.5/0 and 59.1 to 73.9/0 respectively by washing out with water.
lo EXAMPLE V
To examine the possibility of removing other precipitation agents from precipitated protein material, different types of protein sludge were produced by precipitation of effluents containing proteins, using the following precipitation agents:
~auryl sulphate Glyceryl trisulphate Dodesyl-benzene-sulphonic acid Aluminium sulphate The same slaughterhouse effluents were used, with COD = 4.590 mg 0/1, as for the production of ligno-protein sludge in the four preceding examples. Paral}el tests were carried out with effluents from destructive plant for slaughterhouse waste (production of meat-bone meal and technical fats) and with diluted blood water from pig slaughtering.
The separated sludge was brought to pH 9 by the addition of Ca(OH)2, coagulated at 95 C, and centrifugation was carried out. The centrifugates from the different types of sludge were subjected to the same protein precipitation tests as the preceding examples, 5, lo and 15 ml being used as precipitation 10548~6 agent for the same slaughterhouse effluents as described in the preceding examples. Sulphuric acid was added to obtain pH =
3 for all precipitations except precipitation of the centrifugate from the sludge precipitated by aluminium sulphate, for which the pH was adjusted to 6. The decantates from the protein precipitation tests were characterized by determining COD which served for calculating the amount of precipitation agent recovered.
RESULTS
Precipitation Dosage of COD in % COD Line , agent centrifu- decan- reduc-gate for tate tion ml mg o2/1 _ _ _ .
Lauryl sulphate 5 1.426 68,9 lo 1.172 74.5 lo 1.542 66.4 .
Glyceryl .
trisulphate 5 2.380 48.1 lo 1.438 68.7 11 . 15 1.567 65.8 Dodesyl- 5 2.135 53.5 benzene sulphonic lo 1.529 66.7 12 . . 15 1.813 34.o _ Aluminium 5 3.220 29.8 sulphate - lo 3.o72 33.o 13 3 o30 34.o _ .
~548~36 Compared with the results from Example I, line 2, one can see that the precipitation agent is removed from the precipi-tated protein material in the same way. For organic sulphonates and sulphates the degree of recovery is comparable, while it is substantially lower for aluminium sulphate.
Nevertheless it is obvious-that the method as claimed is generally applicable for removing precipitation agents from precipitated protein material in such a form that they can be re-used.
1~
Claims (7)
1. Process for the removal and recovery of precipi-tation agent from precipitated material containing proteins, characterized in that alkaline earth compounds are added to the precipitated material in quantities sufficient to bind the pro-teins and if after such addition the pH number is still below 6.5, a base in the form of alkaline hydroxide is added to pro-duce a pH number higher than 6.5, whereafter the material is heated to a temperature above the coagulation point of the pro-teins present, thereby separating the precipitation agent which is removed whereafter the said precipitation agent can again be used for precipitating proteins.
2. Process according to claim 1, characterized in that calcium chloride, is used as the alkaline earth compound and that NaOH, is used as an alkaline hydroxide.
3. Process according to claim 1, characterized in that Ca(OH)2, is used as the alkaline earth compound and as the base.
4. Process according to claims 1,2 or 3, characteri-zed in that the base is added to obtain a pH between 7.5 and 9.
5. Process according to claims 1,2 or 3, characteri-zed in that the precipitation agent is displaced by warm water by washing the coagulated material.
6. Process according to claims 1, 2 or 3, characteri-zed in that the material is heated by means of superheated steam for a period equivalent to at least 2 minutes.
7. Process according to claims 1, 2 or 3, characteri-zed in that separating the precipitation agent takes place by means of a centrifuge.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NO742703A NO133347C (en) | 1974-07-24 | 1974-07-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1054896A true CA1054896A (en) | 1979-05-22 |
Family
ID=19881744
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA232,085A Expired CA1054896A (en) | 1974-07-24 | 1975-07-23 | Process for removing and recovering precipitation agents from precipitate containing proteinous substances |
Country Status (22)
| Country | Link |
|---|---|
| JP (1) | JPS5149171A (en) |
| AR (1) | AR214710A1 (en) |
| AT (1) | AT337622B (en) |
| BE (1) | BE831625A (en) |
| BR (1) | BR7504675A (en) |
| CA (1) | CA1054896A (en) |
| CH (1) | CH615089A5 (en) |
| CS (1) | CS199594B2 (en) |
| DE (1) | DE2530820C3 (en) |
| DK (1) | DK146613C (en) |
| ES (1) | ES439626A1 (en) |
| FI (1) | FI59016C (en) |
| FR (1) | FR2279676A1 (en) |
| GB (1) | GB1512731A (en) |
| IE (1) | IE41638B1 (en) |
| IS (1) | IS1299B6 (en) |
| IT (1) | IT1040040B (en) |
| NL (1) | NL7508793A (en) |
| NO (1) | NO133347C (en) |
| SE (1) | SE417597B (en) |
| YU (1) | YU36600B (en) |
| ZA (1) | ZA754367B (en) |
Families Citing this family (2)
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|---|---|---|---|---|
| JP5593701B2 (en) * | 2010-01-08 | 2014-09-24 | 三菱レイヨン株式会社 | Method for dewatering organic sludge |
| CN102976579A (en) * | 2012-12-31 | 2013-03-20 | 浙江工商大学 | Method of preparing flocculating agent by utilizing sludge and application thereof |
-
1974
- 1974-07-24 NO NO742703A patent/NO133347C/no unknown
-
1975
- 1975-07-08 ZA ZA00754367A patent/ZA754367B/en unknown
- 1975-07-09 IS IS2280A patent/IS1299B6/en unknown
- 1975-07-10 DE DE2530820A patent/DE2530820C3/en not_active Expired
- 1975-07-17 FI FI752068A patent/FI59016C/en not_active IP Right Cessation
- 1975-07-17 YU YU1823/75A patent/YU36600B/en unknown
- 1975-07-21 IT IT25613/75A patent/IT1040040B/en active
- 1975-07-21 GB GB30463/75A patent/GB1512731A/en not_active Expired
- 1975-07-21 CS CS755134A patent/CS199594B2/en unknown
- 1975-07-22 BR BR7504675*A patent/BR7504675A/en unknown
- 1975-07-22 ES ES439626A patent/ES439626A1/en not_active Expired
- 1975-07-22 CH CH958775A patent/CH615089A5/en not_active IP Right Cessation
- 1975-07-22 JP JP50088923A patent/JPS5149171A/ja active Pending
- 1975-07-22 SE SE7508356A patent/SE417597B/en not_active IP Right Cessation
- 1975-07-23 AT AT569375A patent/AT337622B/en not_active IP Right Cessation
- 1975-07-23 DK DK334375A patent/DK146613C/en not_active IP Right Cessation
- 1975-07-23 NL NL7508793A patent/NL7508793A/en not_active Application Discontinuation
- 1975-07-23 IE IE1649/75A patent/IE41638B1/en unknown
- 1975-07-23 BE BE158511A patent/BE831625A/en not_active IP Right Cessation
- 1975-07-23 CA CA232,085A patent/CA1054896A/en not_active Expired
- 1975-07-23 AR AR259721A patent/AR214710A1/en active
- 1975-07-23 FR FR7523002A patent/FR2279676A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| ATA569375A (en) | 1976-10-15 |
| IS2280A7 (en) | 1975-08-20 |
| SE417597B (en) | 1981-03-30 |
| BE831625A (en) | 1975-11-17 |
| JPS5149171A (en) | 1976-04-28 |
| IE41638L (en) | 1976-01-24 |
| FI59016C (en) | 1981-06-10 |
| DE2530820A1 (en) | 1976-02-05 |
| DK334375A (en) | 1976-01-25 |
| YU36600B (en) | 1984-08-31 |
| GB1512731A (en) | 1978-06-01 |
| AU8334775A (en) | 1977-01-27 |
| CS199594B2 (en) | 1980-07-31 |
| IE41638B1 (en) | 1980-02-13 |
| IS1299B6 (en) | 1987-11-25 |
| DK146613B (en) | 1983-11-21 |
| FR2279676A1 (en) | 1976-02-20 |
| IT1040040B (en) | 1979-12-20 |
| BR7504675A (en) | 1976-07-06 |
| ZA754367B (en) | 1976-06-30 |
| NO133347B (en) | 1976-01-12 |
| CH615089A5 (en) | 1980-01-15 |
| ES439626A1 (en) | 1977-03-01 |
| FI752068A (en) | 1976-01-25 |
| SE7508356L (en) | 1976-01-26 |
| AT337622B (en) | 1977-07-11 |
| NL7508793A (en) | 1976-01-27 |
| DE2530820B2 (en) | 1979-07-05 |
| YU182375A (en) | 1982-02-25 |
| AR214710A1 (en) | 1979-07-31 |
| DE2530820C3 (en) | 1980-03-06 |
| NO133347C (en) | 1976-04-21 |
| FI59016B (en) | 1981-02-27 |
| DK146613C (en) | 1984-05-07 |
| FR2279676B1 (en) | 1982-05-14 |
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