Issue 6, 2014 - Progress in wastewater treatment technology of rubber additives in China

Progress of wastewater treatment technology of rubber additives in China

□ Yan Feng

Rubber additives are an important supporting industry of China's rubber industry, including accelerators, antioxidants, adhesives, coupling agents, sulfur donors and insoluble sulfur and other products
.
Rubber additives wastewater has complex composition, high color, high concentration of organic matter, contains a large amount of inorganic salts and organic sulfur, and is difficult to treat, and it is generally difficult to directly treat
by biochemical methods.
At present, the treatment methods of rubber auxiliary wastewater mainly include distillation evaporation method, extraction method, adsorption method, catalytic oxidation method, biochemical treatment method and combined treatment process
.

1.
Distillation evaporation method

The treatment technology of distillation combined with adsorption has a good effect
on the wastewater treatment of rubber additives, especially for sulfonamide accelerators.
This method combines wastewater treatment with the recovery and reuse of by-reaction products and unreacted raw materials, and shows good application prospects
.

Wang Yiqing of Nanjing Normal University and others have developed the technology of using steam jet heat pump distillation method to pretreat wastewater accelerators CBS, DM and other wastewater, which can reduce the COD of CBS wastewater from 40000mg/L to 1600mg/L, and the equipment structure is simple and the cost is low
.

Wang Liyou of Nanjing Normal University and others used distillation-adsorption combination process to adsorption treatment with activated carbon for the production of difficult-volatile and high-boiling organic substances in the distillate and kettle liquid of rubber auxiliaries, and as a result, COD decreased from 40000mg/L to 150mg/L, the total COD removal rate reached 99.
6%, and the decolorization rate reached 100%.

2.
Extraction method

Su Hong et al.
, School of Environmental Sciences, Yantai University, used toluene as a solvent to extract the organic components in antioxidant RD wastewater, and the results showed that after extraction, the wastewater was hydrolyzed for 6h, aerobic biological oxidation was 10h, and the COD in the effluent was reduced from 12500mg/L at the initial untreated time to less than 100mg/L, and 74% of the raw materials could be recovered, which reached the emission standards
stipulated by the state.

Li Xuekun, School of Chemical Engineering, Northwest University, et al.
used organic solvent complex extraction method to study the recovery process
of acetic acid in rubber auxiliary wastewater.
Acetone is distilled out under reduced pressure, and then trioctylamine is added to extract acetic acid, and acetic acid is recovered by distillation under reduced pressure of the extraction phase, and then recycled, and the wastewater can be discharged
after treatment.

3.
Adsorption method

The adsorption method is a method
that uses a solid adsorbent with strong adsorption capacity to enrich one or several components in wastewater and the solid surface, and then achieve separation.
Commonly used adsorbents are activated carbon and resin
.

Jiangsu University of Science and Technology Tian Yuan and others used granular activated carbon to study the adsorption of wastewater produced by mixing accelerators of
a chemical enterprise.
The results show that when the COD of the influent water is 500mg/L, the dosage of activated carbon in 100ml wastewater is 5g, the reaction time is 50min, the pH value is 4~5, and the oscillation frequency is 100 times/min, the COD removal rate can reach 68%.


Wang Hailing of Nanjing University and others use special adsorption resin treatment accelerator CA to produce wastewater
.
The experimental results show that after the wastewater is adsorbed treatment, the COD concentration drops from about 20000mg/L to less than 300mg/L, and the COD removal rate reaches more than
98%.

4.
Catalytic oxidation

Catalytic oxidation is an effective method for the treatment of high concentration insoluble organic wastewater, organic matter can be oxidized and decomposed by oxidant into CO2, water and other inorganic substances, and then achieve the final harmlessness of pollutants
.
The oxidation rate of this method is relatively fast, the processing efficiency is high, and the scope of application is relatively wide
.

Lu Chun of Zhenjiang Qin Environmental Protection Technology Co.
, Ltd.
took rubber accelerator wastewater as the research object and used chlorine dioxide (ClO2) to carry out catalytic oxidation experiments
on high-concentration rubber accelerator wastewater.
The results show that the optimal operating conditions for ClO2 treatment of rubber accelerator wastewater are: the reaction time is 2h, the pH value is 9, the mass concentration of ClO2 (in terms of effective chlorine) is 500mg/L, and the COD removal rate can reach more than 85%.
Catalytic oxidation improves the B/C ratio of wastewater, and the effluent can reach standard discharge
after biochemical treatment.

Wang Xiangyong, School of Environmental Science and Engineering, Tongji University, et al.
studied the method and effect of
pretreating rubber accelerator wastewater with ozone.
The results show that the removal rate of COD in the treatment of this kind of wastewater is more than 20%, and the removal rate of COD can reach 44% when the pH value is adjusted to 8~9 and marble filler and additives are added, which greatly improves the bio-oxidizability
.

For the rubber vulcanization accelerator NOBS wastewater, Mei Rongwu of Zhejiang Environmental Protection Science and Design Institute first desalted the mother liquor by evaporation, and then catalyzed oxidation with sodium chlorate and concentrated sulfuric acid, and the organic matter in the wastewater was oxidized and decomposed by the strong oxidant chlorine dioxide under the action of the catalyst (activated carbon loaded transition metal oxide, mainly copper oxide), so that the B/C ratio of the pretreated effluent was improved, and good results
were obtained.

5.
Fenton reagent oxidation

Fenton reagent is composed of FeSO4 and H2O2, which can oxidize and decompose macromolecular organic matter in accelerator wastewater into water molecular compounds, so that the biochemicalability of wastewater can be improved, which can be used for the pretreatment of rubber additive wastewater biochemistry
.
Its oxidation effect is closely related
to the ratio, pH value and temperature of FeSO4 and H2O2.
Chen Guangchun, Department of Environmental Engineering, Jiangsu University of Science and Technology, et al.
used Fenton reagent to study
the production wastewater of rubber vulcanization accelerators CBS and NOBS.
The experimental results show that when Fe2+:H2O2=0.
4g/L:18mL/L, pH value is 3, and reaction time is 20min, the removal rate of COD can reach 69.
1%.

6.
Biochemical processing technology

Biochemical treatment is a technology
that uses microorganisms, mainly bacterial metabolism, oxidation, and decomposition, to adsorb soluble organic matter and some insoluble organic matter in wastewater, and convert it into harmless stable substances, so that water can be purified.
Due to the low cost of biochemical treatment, good effect, stable process, simple operation and no secondary pollution, it has developed rapidly
.
It includes aerobic biological treatment and anaerobic biological treatment
.

Zou Xiaoling of Jiangsu University and others use an improved upflow anaerobic sludge bed reactor (UASB) to treat rubber additive wastewater
.
During the test, the influent water concentration COD is 5000~12000mg/L, the pH value > 8.
0, through the acclimation and culture of sludge, the COD removal rate is about 80%, the running volumetric load can reach 6.
0kgCOD/(m3·d), and the pH is stable at about
7.
3.

Zhou Zhaohui of Jiangsu Chunjiang Environmental Protection Technology Co.
, Ltd.
and others use biological nitrogen and phosphorus removal process to treat rubber accelerator wastewater
.
The experimental results show that the effluent index can reach the Class A discharge standard
under the condition that the hydraulic residence time of the whole biochemical system is 24 h.

7.
Combination process

Due to the characteristics of various treatment methods, in the case of poor treatment effect of a single method, the integration and utilization of several methods can not only achieve good treatment results, but also reduce costs and have broad
development prospects.

Shandong Yanggu Huatai Chemical Co.
, Ltd.
adopts the combination process of physical and chemical method and biofilm method (pressure biochemistry + hydrolysis acidification + contact oxidation) to treat the anti-coke agent CTP and accelerator NS wastewater, and has achieved good results
.
The COD of the controlled influent water is in the range of 2000~2500mg/L, and the COD removal rate can reach more than
90% through the cultivation and domestication of microorganisms.
The biggest highlight of the process is the pressure biochemical section, which uses pressure aeration to improve the oxygen transfer rate and transfer efficiency, so as to improve the effect
of biochemical treatment.
The removal rate of COD in this process section can reach 60%.


Sinopec Nanjing Chemical Industry Co.
, Ltd.
adopts the "combination of electrolytic oxidation pretreatment and biochemistry" process to treat wastewater containing accelerator M, and has achieved good results
。 First, the wastewater generated by the crude product promoter M refining process with a COD of about 3200mg/L is collected into the pool, mixed evenly, the pH value is adjusted to 2~4, the solid components are removed by precipitation pressure filtration, and sent to the reduction kettle; Add iron powder to reduce, and then precipitate and filter to remove iron sludge, and continuously enter the electrolytic oxidation of the electrolytic tower at a flow rate of 4m3/h; The current of each electrolytic tower is controlled between 20~30A, the flow rate of hydrogen peroxide is controlled at about 50L/h, and after electrolytic oxidation degrades most of the organic pollutants, the COD of wastewater is reduced to 640mg/L, and the degradation rate reaches 80%.

After biochemical treatment, the effluent meets the specified discharge standards
.

Huang Jin of Beijing University of Chemical Technology et al.
used iron-carbon micro-electrolysis-coagulation-anaerobic hydrolysis-acidification-two-stage contact oxidation biological process to treat rubber auxiliary wastewater
.
The results show that the B/C value of wastewater can be increased from 0.
2 to 0.
65, and the biochemical properties are greatly improved, which is conducive to the subsequent biochemical treatment
of wastewater.

8.
Conclusion

In short, there are many methods of wastewater treatment of rubber additives, and each method has its own characteristics
.
The research of harmless, efficient and resource-based rubber auxiliaries wastewater treatment technology will be the future development direction
.

Rubber auxiliaries wastewater treatment is a systematic engineering, in practical application should be according to their own situation, the wastewater water quality should be systematically analyzed, and then the appropriate method should be adopted
.

While researching and developing new treatment technologies for rubber additives wastewater, new technologies and processes should also be actively adopted, that is, to accelerate the research, development and promotion of clean and green process technologies, improve the utilization rate of raw materials, and reduce unnecessary pollution hazards
.
Technological upgrading of the rubber production process to reduce the discharge
of wastewater at the source.
Only through a two-pronged approach can we truly achieve effective treatment and contribute to
the green development of China's rubber additives industry.