JPH0427492A - Treatment of water - Google Patents

Abstract

PURPOSE:To reduce the total org. carbon content of waste water contg. animal protein by adding a prescribed amt. of a compd. selected among prescribed salts as a flocculant to the water, heating the water after adjustment to pH>=3 and filtering off the resulting flocks. CONSTITUTION:One or more kinds of compds. selected among salts of Fe, Al, Mg, Ca and Zn are added as a flocculant to water contg. animal protein by 5-200wt.% of the total amt. of org. carbon in the protein, the water is adjusted to pH>=3 and heated to >=60 deg.C and the resulting flocks are filtered off. Waste water contg. animal protein, especially fish blood is treated with the flocculant and heated. Flocculated particles become much more filterable than particles flocculated by the conventional heating or treatment with a flocculant, the rate of removal of protein is increased, filtration is accelerated and the total org. carbon content of the waste water can be reduced to about <=150ppm.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for treating high BOD wastewater containing animal blood and the like.

[Conventional technology]

The following methods are known for treating wastewater containing animal blood discharged when fish, animals, or birds are butchered.

■ Heating coagulation filtration or centrifugal separation method ■ Acid coagulation beach filtration or centrifugal separation method ■ Coagulation sedimentation using a coagulant filtration or centrifugation method ■ Coagulation pressurized flotation method using a coagulant ■ Boiling method using an evaporator ■ Electricity Decomposition method ■Reverse osmosis method Heat coagulation method is less effective, as the amount of protein that can be removed by heat coagulation varies depending on the raw material, but is only 70 to 80%.

The coagulation-precipitation method using acid has the advantage that the recovered protein can be easily used, but it is less effective in removing protein than the method of adding a flocculant, and it is difficult to keep the wastewater within the wastewater standards using this method alone. In the precipitation method using a flocculant, a protein precipitate using sodium polyacrylate, polyacrylic acid amide, ferric chloride, metaphosphoric acid, etc. is subjected to TP filtration or centrifugation, but pH adjustment is required. There are two types of coagulated substances: those that settle and those that float.The floating substances often contain oil, so air is blown from below and pressurized to float the coagulated substances and remove them. Add the currently used protein precipitants to ensure proper pH.
Even when treated with H, the removal rate is 50-70 as BOD.
%.

The method of coagulating and precipitating proteins in wastewater by electrolysis has inexpensive equipment, but has problems with processing capacity.

The evaporator method is a method in which wastewater is heated to evaporate, cooled and coagulated before being discharged, and the removal rate of COD and BOD cannot be said to be sufficient. In addition, as a pretreatment, it is necessary to remove as much fat as possible (reverse osmosis method allows only water to pass through, but only water in the wastewater is pushed out to fresh water by pressure through a semi-filtered membrane that does not allow ionized substances to pass through. It is said that the removal rate of BOD and COD is high, but it is difficult to implement unless the organic matter has been treated to some extent and the organic matter has been reduced.

[Problem to be solved by the invention]

An object of the present invention is to provide a method suitable for reducing the total organic carbon content of wastewater containing animal protein as described above.

[Means to solve the problem]

In other words, the present invention uses iron salts, aluminum salts, and magnesium salts as flocculants in water containing animal protein.

One or more compounds selected from calcium salts and zinc salts are added in an amount of 5 to 200% by weight based on the total amount of organic carbon in the protein, the pH is adjusted to 3 or higher, and after heating to 60°C or higher, the aggregates are removed. This is a water treatment method characterized by separating the water into different furnaces.

Compounds used as flocculants include iron chloride, iron sulfate,
Examples include aluminum sulfate, light bread, polyaluminum chloride, sodium aluminate, magnesium chloride, zinc chloride, calcium chloride, etc., and these solutions can be used alone or in combination of two or more. Further, an organic flocculant such as sodium polyacrylate may be used in combination. The amount of flocculant added is 5% of the total organic carbon content of animal protein contained in the wastewater.
-200% by weight, preferably 40-100% by weight. Next, use an alkaline agent to adjust the pH to 3 or higher, preferably pH 6.5.
Adjust to ~7.5. Alkali metal hydroxides, carbonates monobicarbonates, alkaline earth metal hydroxides, ammonia, ammonium carbonate, etc. are used as alkali agents, and dibasic alkali phosphates, tertiary alkali phosphates, etc. are added as buffering agents. can do. If the heating temperature is less than 60°C, protein aggregation will be incomplete, and the optimum temperature is 70 to 80°C.

The aggregates can be separated from house to house by a method such as centrifugal separation in addition to conventional filtration using Hama cloth or the like.

〔Example〕

The effects of the method of the present invention will be explained below using Examples and Comparative Examples.

Example 1 Aquaculture wastewater containing fresh blood from the town (total organic carbon content TOC3,
300 ppm) and an aqueous solution of ferric chloride, aluminum oxide, and magnesium chloride (F e ',
AI! 3゛, total ion concentration of M g z + 101
000pp was added, the pH was adjusted to 6.5 with a caustic soda solution, and after thorough stirring, the mixture was heated to 80°C. ff using p paper
= I made a mistake. The filtration time is 1 minute for 100 cc of sample water. The menstrual fluid is colorless and transparent and has a TOC of 8.
It was 0 ppm.

Example 2 An experiment was conducted in the same manner as in Example 1, except that the amount of the flocculant added was changed to the wastewater. The adjusted pH is 5.0 to 7.0, and the heating temperature is 80°C. The TOC of synovial fluid is as shown in the table below.

Table 1 2 400 9B4
1.000 805
2.000 70
Example 3. Comparative Example 1 An experiment was conducted in the same manner as in Example 1, except that 200 ppm of the same flocculant was added to the wastewater and the heating temperature was changed. p
H was adjusted to 8, and the TOC of the synovial fluid was as shown in the following table.

(Left below) Table 2 At a heating temperature of 60°C, the overspeed for t months is slow. At temperatures above 70°C, the cleaning speed increases to 2 minutes for 100 cc of sample liquid. For comparison, the test was carried out at 50°C, but filtration was not possible.

Example 4 An experiment was conducted in the same manner as in Example 1, except that the type of flocculant added to the wastewater was changed. pH is 7.5, heating temperature is 80℃
It is. The TOC of the disinfectant is as shown in the table below.

(Left below) Table F e Cj! 3Fe" ZnCj!z Zn" Comparative Example 2 When the wastewater from Example 1 was heated without adding a flocculant and filtered at pH 7, the TOC of the solution was as shown in Table 4.

Table 4 [Effects of the Invention] As described above, according to the method of the present invention, wastewater containing animal protein, particularly fresh fish blood, is heat-treated with a flocculant, thereby improving the effectiveness of the conventional heating-only method or the flocculant-only method. It is industrially useful because the aggregated particles become in a form that is extremely easy to excavate, improve the protein removal rate, promote t% overrate, and reduce the total organic carbon content of wastewater to approximately 1 soppm or less. It is.

Claims (3)

[Claims] (1) One or more compounds selected from iron salts, aluminum salts, magnesium salts, calcium salts, and zinc salts are added as a flocculant to water containing animal protein.Total organic carbon content in the animal protein A water treatment method characterized by adding 5 to 200% by weight of water, adjusting the pH to 3 or more, heating to 60° C. or more, and then filtering out aggregates. (2) The water treatment method according to claim 1, wherein the animal protein is a protein in fish blood or a fish body containing fish blood. (3) The water treatment method according to claim 1, wherein the animal protein is a protein in animal blood or bird blood or in an animal body containing these blood.