Method and system unit for flue gas desulfurization and wastewater treatment

[0043] The flue gas desulfurization wastewater treatment method includes the following steps:

[0044] 1. Alkalizing with calcium hydroxide, the pH is about 9.5;

[0045] 2. Add organic sulfide, the addition amount is 50mg/L;

[0046] 3. Added coagulant aluminum sulfate (30mg/L), and 0.1% aqueous flocculant polyacrylamide (8mg/L);

[0047] 4. Carry out water clarification and sludge concentration to separate suspended solids from wastewater;

[0048] 5. Dewatering the concentrated mud.

[0049] The flue gas desulfurization wastewater treatment system device of the present invention is shown in Figures 1 to 4, and the system device is composed of a wastewater buffer tank 5, a neutralization/reaction/flocculation tank 8, a clarification/concentration tank 17, and a water outlet tank 20 connected in series through a pipeline.

[0050] The wastewater buffer tank is shown in Figure 1. The desulfurization wastewater 1 first flows into the wastewater buffer tank 5 by itself, where the volume and quality of the wastewater are adjusted to a certain extent, so a continuous amount of compressed air 4 must be fed into it by a Roots blower. To achieve the purpose of aeration. In addition, the overflow sewage effluent 2 and unqualified effluent 3 of each box will also be sent into it for reprocessing. The hydraulic retention time of this equipment is 10-12 hours. An ultrasonic level gauge 7 is installed on the top of the pool body to measure the water level in the pool online, and control the start and stop of the waste water lifting pump 6 through an automated program. After a certain period of adjustment, the wastewater lift pump sends the wastewater to the neutralization, reaction, and flocculation tanks.

[0051]The neutralization/reaction/flocculation tank is shown in Figure 2. The desulfurization wastewater undergoes a series of physical and chemical reactions in the neutralization/reaction/flocculation tank 8 to remove pollutants in the wastewater, and flows into the clarification/concentration tank by itself. The hydraulic retention time of this equipment is 1 hour. Three mixers are set up in the equipment, 1# mixer 9 and 2# mixer 10 mainly serve the purpose of mixing and mixing uniformly, so that the reaction can proceed smoothly. 3# mixer 11 is the key to the flocculation reaction, and the control of its speed directly affects Flocculation effect. The agitator has a frame structure, and its special mixing form enables small particles to form large flocculation clusters in the flocculation tank without being broken, making it easier to settle in the clarification/concentration tank. Usually the flocculation aid (polyelectrolyte) is directly added to the pipeline.

[0052] In the first tank, add lime emulsion (5-10%) 12 until the PH value reaches about 9.5, so that most of the heavy metal ions in the wastewater are precipitated in the form of hydroxide; in the second tank In this process, a PH meter 16 is set online, and organic sulfide 13 and ferric chloride sulfate 14 are added at the same time. In this process, heavy metal ions that are difficult to be precipitated by lime emulsion react with organic sulfide to form sulfide precipitation. Removal, in addition, ferric sulfate produces ferric hydroxide in the water to form crystal nuclei to promote the next flocculation reaction. In the third tank, polyelectrolyte (PAM) 15 is added to promote the formation of large flocs.

[0053] The clarification/thickening tank is shown in Figure 3. The treated wastewater flows into the clarification/thickening tank 17 by itself, which has the dual functions of water clarification and sludge concentration, and the residence time is about 6-10 hours. A mud scraper 18 is provided in the pool, which has a manual lifting function. The sludge interface meter 19 is set online to automatically control the sludge discharge interval. A small part of the discharged sludge is circulated to the neutralization/reaction/flocculation tank to provide the crystal nuclei required for the flocculation reaction, and most of the sludge is sent to the press The filter performs mechanical dehydration to make the water content of the mud cake less than 75%, which is convenient for transportation and disposal. The supernatant liquid from the clarification/concentration tank flows into the outlet tank through the overflow plate.

[0054] The outlet tank is shown in Figure 4. A PH meter 21 is installed in the outlet tank 20 to detect whether the PH value of the final outlet water meets the discharge requirements (6-9). If the PH value is greater than 9, add concentrated hydrochloric acid (31%) 23 . A mixer 22 and a level gauge 24 are arranged in the box. The residence time in the box is 1 hour. Finally, an online turbidity meter 26 is installed at the outlet. If the turbidity value is within the discharge standard, the main discharge valve is automatically opened and sent to the main discharge port through the outlet pump 25; if the turbidity value exceeds the discharge standard, it will return to the wastewater buffer tank Reprocess.