JP2012250226A - Water-treating solid-liquid separation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform coagulation/sedimentation treatment by suppressing that heavy metals such as complex ions not performed with sedimentation treatment elute as ions to increase sedimentation speed when performing the coagulation/sedimentation treatment of heavy metal ion wastewater by use of iron ions heretofore.SOLUTION: By previously dissolving not only a coagulant containing iron ions but also an inorganic oxygen compound metal ions as water-treating solid-liquid separating agent, the heavy metal ions are coagulated by use of the effect of coprecipitation of the dissolved coagulant containing the iron ions, so that the sedimentation rate is increased to suppress the elution of the heavy metal ions into the wastewater.

Description

  The present invention relates to a solid-liquid separation agent for water treatment and a separation method for wastewater containing heavy metals such as metal surface treatment.

  Conventionally, in metal surface treatment, ferrous sulfate, ferric chloride as a solid-liquid separation agent for wastewater treatment containing heavy metals such as copper, nickel, zinc, chromium, manganese, aluminum, tin, cadmium, lead, arsenic, mercury, etc. A coagulation precipitation method in which iron or an iron salt such as polyferric sulfate is added and the pH is adjusted with sodium hydroxide or calcium hydroxide has been used. As a similar treatment, for example, a wastewater treatment method (Patent Document 1) for removing heavy metals from wastewater generated during washing with dust has been proposed, but gluconic acid, ethylenediamine quaternary can be used as complex-forming substances contained in the surface treatment agent. When acetic acid, a carboxylic acid compound, ammonia, an amine compound, etc. are used, the heavy metal cannot be sufficiently separated into solid and liquid, and partly flows out into the treated water. In addition, a method of coagulating and precipitating by adding an oxidizing agent to an iron salt-based coagulant (Patent Document 2) has been proposed. However, there is a drawback in that the amount of waste increases when the amount of solid sludge that has been separated by precipitation increases. It was.

  A method of using sodium sulfide or a sulfide-based treatment agent in place of or in combination with an iron salt-based flocculant (Patent Document 3) has been proposed. Odor, generation of toxic gases under acidic conditions, etc. Therefore, strict control of the amount added was necessary. In addition, flocs produced by coagulation sedimentation using these have a slow sedimentation speed, so that the flocs flow out along with the flow of the drainage, resulting in exceeding the drainage regulation value for heavy metals.

JP2009-112986A JP2007-38196 JP2009-108553

  Conventionally, in wastewater treatment containing heavy metals such as metal surface treatment, a sufficient treatment effect of heavy metals cannot be obtained only with iron salt-based flocculants such as ferric sulfate, ferric chloride, or polyferric sulfate. In addition, wastewater treatment that causes an increase in the amount of sludge, and use of sodium sulfide or a sulfide-based treatment agent is used for wastewater treatment that does not have good sedimentation in coagulation sedimentation.

  The present invention suppresses the elution of heavy metals such as complex ions that have not been subjected to sedimentation as ions when performing agglomeration and sedimentation using iron ions in heavy metal ion wastewater, and increases the sedimentation rate to perform aggregation and sedimentation. Thus, the present invention provides a solid-liquid separation agent and a separation method that enable treatment of heavy metals.

  In order to achieve the above object, the present invention has the following characteristic configuration.

(1) A solid-liquid separation agent for water treatment and a separation method, wherein the coprecipitation flocculant uses a metal ion additive and an inorganic oxygen compound additive and has an acidic pH of 3 or less.
(2) As metal ion additives, lithium, barium, calcium, strontium, magnesium, zinc, cadmium, aluminum, gallium, sodium, indium, yttrium, cerium, titanium, zirconium, tin, iron, cobalt, nickel, vanadium, A solid-liquid separation agent for water treatment comprising at least one of niobium, tungsten, chromium, molybdenum, manganese, iron, copper, silver, antimony and the like.
(3) Inorganic oxygen compound additives include zinc oxygen compound, cadmium oxygen compound, aluminum oxygen compound, gallium oxygen compound, indium oxygen compound, yttrium oxygen compound, cerium oxygen compound, titanium oxygen compound, zirconium oxygen compound, tin oxygen compound , Iron oxygen compound, cobalt oxygen compound, nickel oxygen compound, vanadium oxygen compound, niobium oxygen compound, tungsten oxygen compound, chromium oxygen compound, molybdenum oxygen compound, manganese oxygen compound, copper oxygen compound, antimony oxygen compound, silicon oxygen compound, calcium A solid-liquid separation agent for water treatment, comprising at least one of an oxygen compound, a magnesium oxygen compound and the like.

  Metal ion additives and inorganic oxygen compound additives include steel smelting wastewater, non-ferrous metal smelting wastewater, polishing wastewater, degreasing wastewater, acid washwater, dye wastewater, pigment wastewater, ceramic wastewater, civil engineering wastewater, and building wastewater. It is a component contained in wastewater treatment wastewater, wastewater from wastewater treatment wastewater, wastewater from wastewater treatment wastewater, etc., and uses at least one kind of wastewater, wastewater or wastewater.

  In the treatment using the solid-liquid separation agent of the present invention, the addition of only the solid-liquid separation agent is effective, but the addition of the iron salt-based flocculant is more effective. Further, the iron salt-based flocculant may be ferric sulfate, ferric chloride, or polyferric sulfate. Addition of 10 to 1000 mg / L as iron is preferable.

  The order of addition of the metal ion additive and the inorganic oxygen compound additive is not particularly limited, but it is preferable to add the metal ion additive after adding the inorganic oxygen compound additive under an acidic pH of 3 or less. .

  According to the present invention, heavy metals in waste water can be insolubilized and solid-liquid separated. Moreover, compared with the conventional flocculant, a coarser floc can be produced | generated, the sedimentation rate can increase, and clear treated water can be obtained.

  Further, the present invention does not require or requires a small amount of an inorganic flocculant such as a calcium compound or an aluminum compound, so that water treatment in harmony with the environment becomes possible.

  The following experiment was conducted to confirm the effect of the solid-liquid separating agent according to the present invention.

Example 1 and Comparative Example 1
The zinc-based plating waste water used in Example 1 is a waste water in which washing water of a zincate bath and a zinc-nickel alloy plating bath is mixed, and the zinc concentration before treatment was 96 mg / L. About 1 L of zinc-based plating wastewater, 1 ml each of metal smelting wastewater and polishing wastewater was added while maintaining an acidic atmosphere of pH 3 or lower. Next, the pH was adjusted to 9-10 with sodium hydroxide (Example 1). For comparison with this, similarly, an iron salt-based flocculant was added to the galvanized wastewater in an acidic atmosphere at pH 3 or lower, and the pH was adjusted to 9-10 with sodium hydroxide. The iron salt was ferric chloride, and 300 mg / L was added as iron (Comparative Example 1).

The treated water was quantified with zinc by atomic absorption spectrophotometry. Table 1 shows the results of zinc treatment tests with the solid-liquid separation agent and the iron salt-based flocculant of the present invention.

Example 2 and Comparative Example 2
The zinc-based plating wastewater used in Example 2 was wastewater in which flush water of an ammonium bath and a zinc-nickel alloy plating bath was mixed, and the zinc concentration before treatment was 413 mg / L. About 1 L of zinc-based plating wastewater, 1 ml each of metal smelting wastewater and polishing wastewater was added while maintaining an acidic atmosphere of pH 3 or lower. Next, the pH was adjusted to 9-10 with sodium hydroxide (Example 2). For comparison with this, similarly, an iron salt-based flocculant was added to the galvanized wastewater in an acidic atmosphere at pH 3 or lower, and the pH was adjusted to 9-10 with sodium hydroxide. The iron salt was ferric chloride, and 300 mg / L was added as iron (Comparative Example 2).

The treated water was quantified with zinc by atomic absorption spectrophotometry. Table 2 shows the results of a test for treating zinc with the solid-liquid separating agent and the iron salt-based flocculant of the present invention.

  Compared with the case of using only the iron salt-based flocculant, the treatment with the solid-liquid separation agent of the present invention showed good coagulation and coprecipitation, increased the sedimentation rate, and clearly improved the treatment effect.

  Ferric sulfate and ferric chloride as solid-liquid separators in wastewater treatment containing heavy metals such as copper, nickel, zinc, chromium, manganese, aluminum, tin, cadmium, lead, arsenic, and mercury in metal surface treatment Alternatively, it is possible to treat wastewater with poor sedimentation properties by adding an iron salt such as polyferric sulfate and adjusting the pH with sodium hydroxide or calcium hydroxide for coagulation sedimentation treatment.

Claims (7)

  A method of using a solid-liquid separation agent for water treatment by dissolving metal ions and inorganic oxygen compounds when aggregating and sedimenting using heavy iron ion wastewater with iron ions.   A method for using a solid-liquid separation agent for water treatment, wherein the coagulation coprecipitation effect is provided in the wastewater to the heavy metal ion wastewater.   3. The solid-liquid separation agent for water treatment to heavy metal ion wastewater according to claim 1, wherein an inorganic oxygen compound additive containing a metal ion additive is used as the additive that gives the coagulation coprecipitation effect. how to use.   As the metal ion additive in the previous paragraph, lithium, barium, calcium, strontium, magnesium, zinc, cadmium, aluminum, gallium, sodium, indium, yttrium, cerium, titanium, zirconium, tin, cobalt, nickel, vanadium, niobium, tungsten, A method of using a solid-liquid separation agent for water treatment in heavy metal ion wastewater, comprising at least one of ions of chromium, molybdenum, manganese, iron, copper, silver, antimony and the like.   The inorganic oxygen compound additive of claim 3 includes zinc oxygen compound, cadmium oxygen compound, aluminum oxygen compound, gallium oxygen compound, indium oxygen compound, yttrium oxygen compound, cerium oxygen compound, titanium oxygen compound, zirconium oxygen compound, tin oxygen Compounds, iron oxygen compounds, cobalt oxygen compounds, nickel oxygen compounds, vanadium oxygen compounds, niobium oxygen compounds, tungsten oxygen compounds, chromium oxygen compounds, molybdenum oxygen compounds, manganese oxygen compounds, copper oxygen compounds, antimony oxygen compounds, silicon oxygen compounds, A method of using a solid-liquid separation agent for water treatment in heavy metal ion wastewater, comprising at least one of a calcium oxygen compound and a magnesium oxygen compound.   The amount of metal ion and inorganic oxygen compound additive added is 0.001 wt% or more and 10 wt% or less, respectively. How to use liquid separation agent.     The solid-liquid separating agent for water treatment to heavy metal ion wastewater according to any one of claims 1 to 6 is steel smelting wastewater, non-ferrous metal smelting wastewater, polishing wastewater, degreasing washing wastewater, acid washing wastewater, dye wastewater. , Use at least one type of wastewater, wastewater or waste contained in components such as pigment wastewater, ceramic wastewater, civil engineering wastewater, building wastewater, wastewater treatment wastewater, wastewater from wastewater treatment wastewater, wastewater from wastewater treatment wastewater An additive characterized by that.