CN101215064B - Simultaneous nitrification and denitrification biological nitrogen removal method in the process of biological treatment of oily wastewater - Google Patents

Abstract

The invention discloses a simultaneous nitrification and denitrification biological denitrification method in the biological treatment process of oily wastewater. The method includes the steps of COD/NH ₄ ⁺ -N ratio control of oily wastewater, oil separation and degreasing treatment, homogeneous treatment of regulating tank and oily sewage oxidation ditch treatment, among which, the oxidation ditch treatment is the first step of oily sewage under the action of rotating disc. It flows in the outer ditch, then enters the middle ditch through the wall hole between the outer and middle ditch, and enters the inner ditch through the middle wall hole after being circulated in the middle ditch; the dissolved oxygen concentration in the outer ditch is controlled at 0-0.5 mg/l; the oily sewage is in the oxidation ditch The treatment time is 16 to 24 hours; the finally treated water enters the secondary sedimentation tank through the inner ditch. On the basis of the three-ditch oxidation ditch, the present invention changes the water intake from the first ditch to only the first ditch, and strengthens the backflow of mud-water mixture in the inner ditch and the outer ditch to optimize the control of the oxidation ditch. Oxygen zone DO concentration, etc., strengthen the nitrification and denitrification denitrification function of nitrifying bacteria and denitrifying bacteria.

Description

Simultaneous nitrification and denitrification biological nitrogen removal method in the process of biological treatment of oily wastewater

technical field

The invention relates to the treatment of oily wastewater in the technical field of environmental protection, in particular to a method for biological treatment of oily wastewater with high ammonia nitrogen (such as oil refinery wastewater) and simultaneous nitrification and denitrification biological denitrification.

Background technique

Nitrogen is an important "eutrophic" substance. Since the 1970s, with the increasingly prominent problem of "eutrophication" in water bodies and the continuous tightening of sewage discharge standards, the traditional biological nitrogen and phosphorus removal technologies and processes have obviously failed to meet the new requirements, and there is an urgent need to study new denitrification Nitrogen theory and techniques to solve problems in wastewater treatment. In particular, the biological denitrification of high-ammonia nitrogen oil refinery wastewater, chemical fertilizer wastewater, landfill leachate, etc. has become a hot research topic for environmental science and technology workers around the world.

Biological nitrogen removal is a cost-effective method. The research on biological denitrification has a history of more than 110 years. The traditional biological denitrification process needs to go through two stages of nitrification and denitrification. The biological denitrification process can go through two ways of NO ₃ ^- and NO ₂ ^- . The former is called the whole process. Nitrification and denitrification, the latter is called short-range (or simple) nitrification and denitrification. For more than 100 years, scientists and engineers have researched and developed the A/O process, UCT process, Bardenpho process, Phoredox (A ² /O) process, JBH process, and SBR process for biological nitrogen removal for the above two stages of nitrification and denitrification. , VIP process, AAA process, etc. These traditional biological denitrification processes are all graded nitrification and denitrification processes that separate the nitrification and denitrification processes in an aerobic zone and an anaerobic zone.

As shown in Figure 1, the Orbal oxidation ditch is mainly composed of outer ditch, middle ditch and inner ditch. There are 4 rotating discs in the ditch, see point M in the attached drawing, the wall holes between the outer ditch, the middle ditch and the inner ditch are set in front of the third rotating disc, and the return sludge is led from the sludge pumping room to the first rotating disc Before entering the oxidation ditch from the outer ditch. The existing Orbal oxidation ditch sewage treatment method is to lead the oily sewage to the front of the first rotating disc, and simultaneously enter the water from the outer, middle and inner ditch. , enter the middle ditch through the wall hole between the outer and middle ditch, and then enter the inner ditch through the wall hole between the middle and inner ditch in front of the third turntable after circulation, and then go to the secondary sedimentation tank for sedimentation; the sewage entering the middle ditch flows through circulation Afterwards, the wall hole between the middle and inner ditch in front of the third turntable enters the inner ditch, and then goes to the secondary settling tank for sedimentation; the sewage entering the inner ditch is circulated and then goes to the secondary settling tank for sedimentation. The main problems in the existing Orbal oxidation ditch treatment method are: large fluctuations of influent COD/NH4+-N, high oil content in influent water, incomplete nitrification and denitrification caused by simultaneous inflow of three oxidation ditches, and ineffective control of dissolved oxygen. Regularity, low sludge volume, etc. As a result, the biological removal and denitrification (including nitrification and denitrification) of organic matter (COD, including oil, phenolic substances, etc.) are poor, and the emissions cannot be stably met.

Contents of the invention

The purpose of the present invention is to solve the problem of large COD/NH ₄ ⁺ -N fluctuations in the existing oil refinery wastewater Orbal oxidation ditch treatment process, excessive oil content in the influent, water inflow into three oxidation ditches at the same time, irregular dissolved oxygen control, and pollution. In view of the shortcomings of low sludge content, a simultaneous nitrification and denitrification biological denitrification method was proposed in the process of biological treatment of oily wastewater to achieve NOx-N concentration below 30mg/l.

The purpose of the present invention is achieved through the following technical solutions:

A simultaneous nitrification and denitrification biological denitrification method in the biological treatment of oily wastewater, comprising the following steps and process conditions:

(1) COD/NH ₄ ⁺ -N ratio control of oily wastewater: oily wastewater is refined through the alkali injection process of ammonia stripping to extract ammonia from oily wastewater to regulate the concentration of NH4+-N, so that the COD/NH4+-N ratio of oily wastewater 2.86-4.3;

(2) Oil separation and oil removal treatment: the oily wastewater treated in step (1) is separated from oil and water through the advection grease trap, and the oil content of the oily wastewater is controlled to be ≤ 150mg/l, and then further separated through the inclined plate grease trap Separation of oil and water, control the oil content of oily wastewater to ≤50mg/l; configure the inorganic polymer flocculant polyaluminum chloride aqueous solution according to the mass concentration of 5-10%, and configure the organic polymer flocculant GD- according to the mass concentration of 0.1-0.8% 112 aqueous solution, the polyaluminum chloride aqueous solution and the organic polymer flocculant GD-112 aqueous solution are compounded at a ratio of 6 to 10:1 as a flotation agent, and the flotation agent is added to the flotation at a ratio of 1 to 2:1 of the oil concentration in the influent Select the pool, act for 1-3 hours, and then use the flotation scraper to clean the scum, and control the oil content to ≤15mg/l;

(3) Homogeneous treatment in the regulating tank: the wastewater settles in the regulating pond for 1 to 3 hours;

(4) Oxidation ditch treatment of oily sewage: After step (3), the homogeneously treated wastewater enters the Orbal oxidation ditch from the outer ditch, flows in the outer ditch under the action of the rotating disc, then enters the middle ditch through the wall hole between the outer and middle ditch, and passes through After circulation treatment in the middle ditch, it enters the inner ditch through the middle wall hole; the rotation speed of each rotary plate is 43-55rpm, and the dissolved oxygen concentration in the outer ditch is controlled to be 0-0.5mg/l; the treatment time of oily sewage in the oxidation ditch is 16-24h ; Finally, the treated water enters the second sedimentation tank through the inner ditch for 1-3 hours.

In order to further realize the object of the present invention, said control of the dissolved oxygen concentration in the outer groove is 0-0.5 mg/l, and at the same time, it also includes controlling the dissolved oxygen concentration in the middle groove and the inner groove to be 0.5-1.5 mg through the speed regulation of each rotating disk /l and 1.5-2.5mg/l.

The treatment time of the oily sewage in the oxidation ditch is 16-24 hours, which means that the treatment times in the outer ditch, the middle ditch and the inner ditch are 8-12 hours, 5-7 hours and 3-5 hours respectively.

The water inflow of the oxidation ditch is 300-500m3/h.

The amount of return sludge in the oxidation ditch accounts for 100-150wt% of the water inflow.

The concentration of the oxidation ditch sludge is 3-5g/l.

The step (3) also includes adjusting the pH value of the oily waste water, and the pH value is adjusted to 7.3-8.5 by adding alkaline or acidic substances when the waste water is homogeneously treated in the step (3).

The present invention ensures stable COD/NH ₄ ⁺ -N ratio range of influent water, reduces excessive oil content in influent water, only enters water in the first ditch in the oxidation ditch, improves dissolved oxygen concentration, and adjusts Orbal oxidation ditch sludge concentration to ensure The number of nitrifying and denitrifying bacteria, the NOx-N concentration of the oily wastewater after treatment is below 30mg/l.

Principle of the present invention:

The electronic metering equation of nitrification reaction firstly proposed by the inventor in the world:

$\frac{\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 40</span>}}\mathrm{<span\; class="notranslate">\; N</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}^{<span\; class="notranslate">\; +</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 4</span>}}{\mathrm{<span\; class="notranslate">\; o</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 4</span>}}\mathrm{<span\; class="notranslate">\; HC</span>}{\mathrm{<span\; class="notranslate">\; o</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}^{<span\; class="notranslate">\; -</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 20</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 7</span>}}{\mathrm{<span\; class="notranslate">\; o</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 8</span>}}\mathrm{<span\; class="notranslate">\; N</span>}{\mathrm{<span\; class="notranslate">\; o</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}^{<span\; class="notranslate">\; -</span>}$

$<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 4</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 20</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}^{<span\; class="notranslate">\; +</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 6</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 40</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; o</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

$\frac{\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 3</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 60</span>}}\mathrm{<span\; class="notranslate">\; N</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}^{<span\; class="notranslate">\; +</span>}\frac{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 4</span>}}{\mathrm{<span\; class="notranslate">\; o</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 4</span>}}\mathrm{<span\; class="notranslate">\; HC</span>}{\mathrm{<span\; class="notranslate">\; o</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}^{<span\; class="notranslate">\; -</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 20</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 7</span>}}{\mathrm{<span\; class="notranslate">\; o</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 6</span>}}\mathrm{<span\; class="notranslate">\; N</span>}{\mathrm{<span\; class="notranslate">\; o</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; -</span>}$

$<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 3</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 15</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}^{<span\; class="notranslate">\; +</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 9</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 60</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; o</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

And biological denitrification COD/N ratio electronic metrology relationship:

$\frac{\mathrm{<span\; class="notranslate">\; COD</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; N</span>}{\mathrm{<span\; class="notranslate">\; o</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2.86</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1.628</span>}\mathrm{<span\; class="notranslate">\; Y</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

$\frac{\mathrm{<span\; class="notranslate">\; COD</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; N</span>}{\mathrm{<span\; class="notranslate">\; o</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1.714</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1.628</span>}\mathrm{<span\; class="notranslate">\; Y</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

The analysis of the above formulas (1) to (4) shows that the short-range nitrification and denitrification through the nitrite nitrogen approach has significant advantages compared with the traditional nitrification and denitrification process. One is to save 25% of the oxygen demand in the nitrification stage, and the other is The denitrification stage saves about 40% of the carbon source; the experimental research results show that the COD/N ratio required for the whole process of nitrification and denitrification through the NO ₃ ^-way is generally in the range of 2.86-4.3. Therefore, how to realize the metrological optimal control of simultaneous nitrification and denitrification (SND) plays an important role in ensuring the denitrification effect of SND.

Features and effects of the present invention are:

(1) The concentration of oxidation ditch sludge has been increased by nearly 20%, and various conditions have been optimized;

(2) The pass rate of COD in the effluent of oil refinery wastewater has increased significantly. After the implementation, it has increased by 16.67% compared with before the implementation, and has maintained a stable level of pass rate;

(3) Before the implementation of this technology, the qualified rate of effluent NH ₄ ⁺ -N (the concentration of effluent NH ₄ ⁺ -N is usually about 130mg/l) is very low (0-55%). After two months of technical optimization, the NH ₄ ⁺ -N pass rate rapidly increased to over 90% and remained stable;

(4) The concentration of NOx-N in the effluent of the oxidation ditch has changed greatly before and after the technical transformation, from the monthly average of 66.8mg/l during the technical transformation to below 10mg/l, which is far lower than the discharge standard of 50mg/l for this type of wastewater;

(5) The qualified rate of other control indicators has been greatly improved, such as the treatment effect of sulfur, phenol, and cyanide in oil refining wastewater is better: the qualified rate of "phenol" has increased by 6.18%, reaching 99.14%; the qualified rate of cyanide and sulfur rate increased to 100%.

Description of drawings

Figure 1 is a schematic diagram of the Orbal oxidation ditch structure.

Detailed ways

The specific implementation of the method of the present invention will be further described below in conjunction with the examples, but the scope of protection claimed by the present invention is not limited to the scope expressed in the examples.

The Orbal oxidation ditch of the refinery wastewater of the present invention is structurally the same as the prior art oxidation ditch shown in Figure 1, the difference is that when the wastewater is treated, the wastewater is controlled to enter only from the outer ditch 1, and then flows into the middle ditch 2 and the inner ditch in turn. 3. The mixed liquid effluent from the aeration tank flows into the secondary sedimentation tank. The return sludge is returned to the outer ditch 1 by the secondary settling tank. Oxygenation is accomplished through aeration and swirling discs. This oxygenation method also makes the mixed liquid circulate in a suspended state in each channel. Like other closed-circuit biological reaction tanks, the mixed liquid will circulate in its channel for many times and then flow into the next channel. Direction) can be flexibly changed, thus allowing the oxygen supply of each channel to change, and the speed and immersion depth of the aeration rotor can also be adjusted according to the oxygenation requirements. The outer groove 1 accounts for about 50-55% of the volume of the whole system, the middle groove 2 and the inner groove 3 respectively account for about 30-35% and 15-20%.

An oil refinery wastewater treatment in Guangzhou adopts a three-ditch oxidation ditch process, and its treatment scale is 10,000-20,000 tons/day; in front of the oxidation ditch are stripped ammonia refining, regulating tanks, advection grease traps, pH adjustment, mixing, flotation, homogenization, etc. Water quality and other pretreatment processes. Its organic components are mainly oily sewage produced after oil refining, and contain a large amount of ammonia nitrogen. The removal of organic matter and ammonia nitrogen is mainly achieved through the degradation of various microorganisms in the activated sludge in the oxidation ditch. Due to the shortcomings of the original process, such as large fluctuations in influent COD/NH ₄ ⁺ -N, high oil content in influent water, simultaneous water inflow into three oxidation ditches, irregular dissolved oxygen control, and low sludge volume, it has been difficult to meet the discharge standards. , especially the treatment effect of ammonia nitrogen is poor, and the compliance rate is only 0-50%, which causes great pollution to the local water environment. By adopting the technical solutions of the following embodiments 1 to 4 of the present invention, the above-mentioned problems are solved, and the effects of highly efficient removal of organic matter and SND denitrification are achieved.

Example 1

The simultaneous nitrification and denitrification biological denitrification method in the biological treatment process of an oil refinery wastewater in Guangzhou includes the following steps and process conditions:

(1) Control of COD/NH ₄ ⁺ -N ratio in oily wastewater: Oily wastewater is purified by stripping ammonia and alkali injection process, and NH ₃ , H ₂ S and CO ₂ are obtained from the vapor phase by heating and stripping, and the sewage is purified. The concentration of ammonia in oily wastewater is greatly reduced and the concentration of NH ₄ ⁺ -N in sewage can be regulated (in addition, the difference in solubility of NH ₃ , H ₂ S and CO ₂ obtained in the vapor phase at different temperatures can be separated by condensation Ammonia and H ₂ S), control the COD/NH ₄ ⁺ -N ratio of oily wastewater to about 2.87.

(2) oil separation and oil removal treatment: the treated waste water through step (1) carries out oil-water separation through advection grease trap (oil content 1980mg/l), controls the oil content of oily waste water to be 148mg/l), and then Separation of oil and water in the board grease trap to control the oil content of oily wastewater to 47mg/L; then, configure an aqueous solution of inorganic polymer flocculant polyaluminum chloride according to a mass concentration of 5%, and configure an organic polymer flocculant according to a mass concentration of 0.2% Flocculant GD-112 aqueous solution, the polyaluminum chloride aqueous solution and the organic polymer flocculant GD-112 aqueous solution are compounded at a ratio of 8:1 as a flotation agent, and the flotation agent is added to float at a ratio of 2:1 to the oil concentration in the influent. Select the pool, use it for 3 hours, and then use the flotation scraper to clean the scum, which can further remove about 90% of the slick oil, and control the oil content ≤ 18mg/l.

(3) Homogenization treatment in the regulating tank: the wastewater is settled in the regulating pond for 2 hours to make the water quality homogeneous; the pH value of the oily wastewater is adjusted by adding NaOH to adjust the pH value to 8.1-8.5 when the wastewater is homogenized.

(4) Oxidation ditch treatment of oily sewage: after step (3), the homogeneously treated wastewater enters the Orbal oxidation ditch from the outer ditch, and the water inflow of the oxidation ditch is 450m ³ /h. The wall hole between the ditch enters the middle ditch, and then enters the inner ditch through the middle wall hole after being circulated in the middle ditch; the dissolved oxygen concentration of the outer ditch, the middle ditch, and the inner ditch are controlled to be 0.3- 0.5mg/l, 0.8-1.5mg/l, 2.0-2.5mg/l; the treatment time of oily sewage in oxidation ditch is 20h, and the treatment time in outer ditch, middle ditch and inner ditch is 10h, 6h, 4h respectively ; The amount of return sludge in the oxidation ditch accounts for 100% of the influent, and the concentration of the sludge in the oxidation ditch is 3.5g/l. Finally, the treated water enters the secondary sedimentation tank through the inner ditch for 3 hours.

Example 2

The simultaneous nitrification and denitrification biological denitrification method in the biological treatment process of an oil refinery wastewater in Guangzhou includes the following steps and process conditions:

(1) Control of COD/NH ₄ ⁺ -N ratio in oily wastewater: Oily wastewater is purified by stripping ammonia and alkali injection process, and NH ₃ , H ₂ S and CO ₂ are obtained from the vapor phase by heating and stripping, and the sewage is purified. The concentration of ammonia in oily wastewater is greatly reduced and the concentration of NH ₄ ⁺ -N in sewage can be regulated (in addition, the difference in solubility of NH ₃ , H ₂ S and CO ₂ obtained in the vapor phase at different temperatures can be separated by condensation Ammonia and H ₂ S), control the COD/NH ₄ ⁺ -N ratio of oily wastewater to about 3.05;

(2) oil separation and oil removal treatment: the oily waste water processed through step (1) carries out oil-water separation through the advection grease trap (oil content 1970mg/l), and the oil content of the control oily waste water is 149 mg/l), and then passes through the ramp Further oil-water separation is carried out in the board grease trap, and the oil content of the oily wastewater is controlled to 46 mg/L; then, the aqueous solution of inorganic polymer flocculant polyaluminum chloride is prepared according to the mass concentration of 7%, and the organic polymer flocculant is prepared according to the mass concentration of 0.4%. Flocculant GD-112 aqueous solution, the polyaluminum chloride aqueous solution and the organic polymer flocculant GD-112 aqueous solution are compounded at a ratio of 8:1 as a flotation agent, and the flotation agent is added to float at a ratio of 2:1 to the oil concentration in the influent. Select the pool, let it work for 1 hour, and then use the flotation scraper to clean the scum, which can further remove about 90% of the slick oil, and control the oil content ≤ 17mg/l.

(3) Homogeneous treatment in the regulating tank: the wastewater is deposited in the regulating tank for 2 hours to make the water quality uniform; the pH value of the oily wastewater is adjusted by adding NaOH to adjust the pH value to 8-8.5 when the wastewater is homogeneously treated;

(4) Oxidation ditch cyclic biological treatment: after step (3) the homogeneously treated waste water enters the Orbal oxidation ditch from the outer ditch, and the water inflow of the oxidation ditch is 460m ³ /h. The wall hole between the ditch enters the middle ditch, and then enters the inner ditch through the middle wall hole after being circulated in the middle ditch; by adjusting the rotation speed of the rotating disc to 50rpm, the dissolved oxygen concentration of the outer ditch, the middle ditch, and the inner ditch are controlled to be 0.3- 0.4mg/l, 0.9-1.6mg/l, 2.0-2.5mg/l; the treatment time of oily sewage in oxidation ditch is 19h, and the treatment time in outer ditch, middle ditch and inner ditch is 8h, 7h, 4h respectively ; The amount of returning sludge in the oxidation ditch accounts for 100% of the influent, and the concentration of the sludge in the oxidation ditch is 3.7g/l. Finally, the treated water enters the secondary sedimentation tank through the inner ditch for 3 hours.

Example 3

The simultaneous nitrification and denitrification biological denitrification method in the biological treatment process of an oil refinery wastewater in Guangzhou includes the following steps and process conditions:

(1) Control of COD/NH ₄ ⁺ -N ratio in oily wastewater: Oily wastewater is purified by stripping ammonia and alkali injection process, and NH ₃ , H ₂ S and CO ₂ are obtained from the vapor phase by heating and stripping, and the sewage is purified. The concentration of ammonia in oily wastewater is greatly reduced and the concentration of NH ₄ ⁺ -N in sewage can be regulated (in addition, the difference in solubility of NH ₃ , H ₂ S and CO ₂ obtained in the vapor phase at different temperatures can be separated by condensation Ammonia and H ₂ S), control the COD/NH ₄ ⁺ -N ratio of oily wastewater to about 3.6;

(2) oil separation, degreasing treatment: the oily wastewater processed through step (1) carries out oil-water separation through the advection grease trap (oil content 1980mg/l), and the oil content of the control oily wastewater is 148mg/l,), and then The slanted plate grease trap is further separated from oil and water, and the oil content of oily wastewater is controlled to 47 mg/L; then, an aqueous solution of inorganic polymer flocculant polyaluminum chloride is prepared according to a mass concentration of 7%, and an organic high-molecular-weight solution is prepared according to a mass concentration of 0.5%. Molecular flocculant GD-112 aqueous solution, polyaluminum chloride aqueous solution and organic polymer flocculant GD-112 aqueous solution are compounded at a ratio of 8:1 as a flotation agent, and the flotation agent is added at a ratio of 1:1 to the oil concentration in the influent The flotation tank is used for 1-3 hours, and then the scum is cleaned with a flotation scraper, which can further remove about 90% of the slick oil, and control the oil content ≤ 16mg/l.

(3) Homogenization treatment in the adjustment tank: the wastewater is deposited in the adjustment tank for 1 hour; the pH value of the oily wastewater is adjusted by adding H ₂ SO ₄ to adjust the pH value to 7.8-8.5 when the wastewater is homogenized.

(4) Oxidation ditch cyclic biological treatment: after step (3) the homogeneously treated waste water enters the Orbal oxidation ditch from the outer ditch, and the water inflow of the oxidation ditch is 460m ³ /h. The wall hole between the ditch enters the middle ditch, and then enters the inner ditch through the middle wall hole after circulating treatment in the middle ditch; by adjusting the rotation speed of the rotating disc to 46rpm, the dissolved oxygen concentration of the outer ditch, the middle ditch, and the inner ditch are controlled to be 0.1- 0.4mg/l, 0.8-1.4mg/l, 1.7-2.4mg/l; the treatment time of oily sewage in oxidation ditch is 24h, and the treatment time in outer ditch, middle ditch and inner ditch is 12h, 7h, 5h respectively ; The amount of return sludge in the oxidation ditch accounts for 120% of the water inflow, and the concentration of the sludge in the oxidation ditch is 3.7g/l. Finally, the treated water enters the secondary sedimentation tank through the inner ditch for 3 hours.

Example 4

The simultaneous nitrification and denitrification biological denitrification method in the biological treatment process of an oil refinery wastewater in Guangzhou includes the following steps and process conditions:

(1) Control of COD/NH ₄ ⁺ -N ratio in oily wastewater: Oily wastewater is purified by stripping ammonia and alkali injection process, and NH ₃ , H ₂ S and CO ₂ are obtained from the vapor phase by heating and stripping, and the sewage is purified. The concentration of ammonia in oily wastewater is greatly reduced and the concentration of NH ₄ ⁺ -N in sewage can be regulated (in addition, the difference in solubility of NH ₃ , H ₂ S and CO ₂ obtained in the vapor phase at different temperatures can be separated by condensation Ammonia and H ₂ S), control the COD/NH ₄ ⁺ -N ratio of oily wastewater to about 4.2;

(2) Grease separation, degreasing treatment: carry out oil-water separation through advection grease trap (oil content 1970mg/l) through step (1) process containing waste water, control the oil content of oily waste water to be 147mg/l,), then pass through The inclined plate grease trap is further separated from oil and water, and the oil content of oily wastewater is controlled to 48 mg/L; then, an aqueous solution of inorganic polymer flocculant polyaluminum chloride is prepared according to a mass concentration of 8%, and an organic high-molecular-weight solution is prepared according to a mass concentration of 0.7%. Molecular flocculant GD-112 aqueous solution, polyaluminum chloride aqueous solution and organic polymer flocculant GD-112 aqueous solution are compounded at a ratio of 8:1 as a flotation agent, and the flotation agent is added at a ratio of 2:1 to the oil concentration in the influent The flotation tank is used for 1-3 hours, and then the scum is cleaned with a flotation scraper, which can further remove about 90% of the slick oil, and control the oil content ≤ 15mg/l.

(3) Homogenization treatment in the adjustment tank: the wastewater is deposited in the adjustment tank for 1 hour; the pH value of the oily wastewater is adjusted by adding H ₂ SO ₄ to adjust the pH value to 7.9-8.7 when the wastewater is homogenized.

(4) Oxidation ditch cyclic biological treatment: after step (3) the homogeneously treated waste water enters the Orbal oxidation ditch from the outer ditch, and the water inflow of the oxidation ditch is 430m ³ /h. The wall hole between the ditch enters the middle ditch, and then enters the inner ditch through the middle wall hole after circulating treatment in the middle ditch; by adjusting the rotation speed of the rotating disc to 46rpm, the dissolved oxygen concentration of the outer ditch, the middle ditch, and the inner ditch are controlled to be 0.1- 0.3mg/l, 0.6-1.3mg/l, 1.5-2.3mg/l; the treatment time of oily sewage in oxidation ditch is 16h, and the treatment time in outer ditch, middle ditch and inner ditch is 8h, 5h and 3h respectively ; The amount of return sludge in the oxidation ditch accounts for 120% of the water inflow, and the concentration of the sludge in the oxidation ditch is 3.7g/l. Finally, the treated water enters the secondary sedimentation tank through the inner ditch for 2 hours of sedimentation.

The effect of the above-mentioned embodiment will be described below.

(1) Pass rate of NH ₄ ⁺ -N

Before the technical transformation and optimization of the refinery wastewater biological treatment device, the qualified rate of NH ₄ ⁺ -N in the effluent from the oxidation ditch was very low (the concentration of NH ₄ ⁺ -N in the effluent was usually about 130 mg/l). The ₄ ⁺ -N pass rate has rapidly increased to over 90%, and it has remained so for more than 5 years.

(2) Changes of NOx-N concentration in the effluent before and after the technical transformation of the oxidation ditch

By adopting the optimization measures of simultaneous nitrification and denitrification described in Examples 1 to 4 above, the concentration of NOx-N in the effluent of the oil refinery wastewater treatment plant (20000 m ³ /d) decreased significantly, as shown in Table 1.

Table 1

The prior art in Table 1 refers to the concentration of NOx-N in the oxidation ditch effluent of an oil refinery wastewater in Guangzhou before the technical solutions of Examples 1 to 4 of the present invention were adopted. As can be seen from the above table 1, after adopting the technical solutions of embodiments 1 to 4 of the present invention, the concentration of nitrate nitrogen has dropped significantly, from the monthly average of 66.8mg/l in the prior art to below 10mg/l, which is far lower than this The discharge standard of similar wastewater is 50mg/l. It shows that the denitrification in the oxidation ditch has been significantly enhanced, and the expected simultaneous nitrification and denitrification has been achieved and tended to be stable. It has maintained a stable operation effect for many years. Based on the above qualification rate of ammonia nitrogen removal, it can be seen that the effect of simultaneous nitrification and denitrification in the biochemical reaction device is very obvious.

(3) COD pass rate

Table 2 is the statistical table of COD in the effluent of the oil refining industry wastewater treatment plant in the prior art and Example 1. It can be seen from the table that the qualified rate of COD in the effluent of the device has increased significantly, and it has increased by 16.67% compared with before the implementation, and has maintained a stable level of qualified rate.

Table 2

current technology Example 1 time Pass rate(%) time Pass rate(%) January of the first year 73 May of the first year 77 2 87 6 76 3 66.7 7 97 4 68.1 8 76 5 77.4 9 64 6 67.7 10 97 7 43.3 11 80.7 8 33.3 12 97 9 58  January of the third year 100 10 90 2 100 11 93.3 3 100 12 83.3 4 100 January of the second year 97 5 100 2 50 6 97 3 83 7 100 4 100

Average 73.19 / 89.86

(4) Pass rate of other control indicators

It can be seen from Table 3 that after adopting the technical scheme of Example 1, the treatment effect on sulfur, phenol, and cyanide in oil refinery wastewater is better, and a higher pass rate level has been maintained. Among them, the qualified rate of "phenol" increased by 6.18%, reaching 99.14%; the qualified rate of cyanide and sulfur increased to 100%.

table 3

current technology Example 1 time sulfur Phenol Cyanide time sulfur Phenol Cyanide January of the first year 100 100 100 5 100 96.7 100 2 100 100 100 6 100 100 100 3 100 100 100 7 100 100 100 4 100 100 100 8 100 96.7 100 5 96.7 83.3 95.2 9 100 93.7 100 6 96.7 54.8 80.9 10 100 100 100 7 100 96.7 100 11 100 100 100 8 100 86.2 100 12 100 96.7 100 9 100 71 100 January of the third year 100 100 100 10 100 90 100 2 100 100 100 11 100 96.8 100 3 100 100 100 12 100 100 100 4 100 100 100 January of the second year 100 100 100 5 100 100 100 2 100 100 100 6 100 100 100 3 100 92.6 100 7 100 100 100 4 100 100 100 8 100 100 100 / / / 9 100 98.9 100 / / / 10 100 100 100

/ / / 11 100 100 100 / / / 12 100 100 100 average value 99.59 91.96 98.51 / 100 99.14 100

Claims (7)

1. A simultaneous nitrification and denitrification biological denitrification method in an oily wastewater biological treatment process, characterized in that it comprises the following steps and process conditions: (1) COD/NH ₄ ⁺ -N ratio control of oily wastewater: The ammonia in oily wastewater is extracted through the alkali injection process of ammonia stripping to regulate the concentration of NH ₄ ⁺ -N, so that the COD/NH ₄ of oily wastewater ⁺ -N ratio is 2.86-4.3; (2) Oil separation and oil removal treatment: the oily wastewater treated in step (1) is separated from oil and water through the advection grease trap, and the oil content of the oily wastewater is controlled to be ≤ 150mg/l, and then further separated through the inclined plate grease trap Separation of oil and water, control the oil content of oily wastewater to ≤50mg/l; configure the inorganic polymer flocculant polyaluminum chloride aqueous solution according to the mass concentration of 5-10%, and configure the organic polymer flocculant GD- according to the mass concentration of 0.1-0.8% 112 aqueous solution, the polyaluminum chloride aqueous solution and the organic polymer flocculant GD-112 aqueous solution are compounded at a ratio of 6 to 10:1 as a flotation agent, and the flotation agent is added to the flotation at a ratio of 1 to 2:1 of the oil concentration in the influent Select the pool, act for 1-3 hours, and then use the flotation scraper to clean the scum, and control the oil content to ≤15mg/l; (3) Homogeneous treatment in the regulating tank: the wastewater settles in the regulating pond for 1 to 3 hours; (4) Oxidation ditch treatment of oily sewage: After step (3), the homogeneously treated wastewater enters the Orbal oxidation ditch from the outer ditch, flows in the outer ditch under the action of the rotating disc, then enters the middle ditch through the wall hole between the outer and middle ditch, and passes through After circulation treatment in the middle ditch, it enters the inner ditch through the middle wall hole; the rotation speed of each rotary plate is 43-55rpm, and the dissolved oxygen concentration in the outer ditch is controlled to be 0-0.5mg/l; the treatment time of oily sewage in the oxidation ditch is 16-24h ; Finally, the treated water enters the second sedimentation tank through the inner ditch for 1-3 hours. the 2. The simultaneous nitrification and denitrification biological denitrification method in the biological treatment process of oily wastewater according to claim 1, characterized in that, while controlling the dissolved oxygen concentration in the outer ditch to be 0 to 0.5mg/l, it also includes passing through each turn The speed of the disc is adjusted to control the dissolved oxygen concentration of the middle groove and the inner groove to 0.5-1.5mg/l and 1.5-2.5mg/l respectively. the 3. The simultaneous nitrification and denitrification biological denitrification method in the biological treatment process of oily wastewater according to claim 1, characterized in that the treatment time of oily wastewater in the oxidation ditch is 16 to 24 hours and refers to the outer ditch, the middle ditch and the inner ditch The processing time is 8～12h, 5～7h and 3～5h respectively. 4. The method for simultaneous nitrification and denitrification biological denitrification during the biological treatment of oily wastewater according to claim 1, characterized in that the water inflow of the oxidation ditch is 300-500 m ³ /h. 5. the simultaneous nitrification and denitrification biological denitrification method in the oily wastewater biological treatment process according to claim 1, is characterized in that the reflux sludge amount of the oxidation ditch accounts for 100-150wt% of the influent. the 6. The simultaneous nitrification and denitrification biological denitrification method during the biological treatment of oily wastewater according to claim 1, characterized in that the concentration of the oxidation ditch sludge is 3-5g/l. the 7. the simultaneous nitrification and denitrification biological denitrification method in the oily wastewater biological treatment process according to claim 1, characterized in that said step (3) also includes pH adjustment of oily wastewater, by homogenizing in step (3) When treating wastewater, add alkaline or acidic substances to adjust the pH value to 7.3-8.5. the