Identification and removal of polycyclic aromatic hydrocarbons in wastewater treatment processes from coke production plants

Abstract

Identification and removal of polycyclic aromatic hydrocarbons (PAHs) were investigated at two coke plants located in Shaoguan, Guangdong Province of China. Samples of raw coking wastewaters and wastewaters from subunits of a coke production plant were analyzed using gas chromatography-mass spectrometry (GC/MS) to provide a detailed chemical characterization of PAHs. The identification and characterization of PAH isomers was based on a positive match of mass spectral data of sample peaks with those for PAH isomers in mass spectra databases with electron impact ionization mass spectra and retention times of internal reference compounds. In total, 270 PAH compounds including numerous nitrogen, oxygen, and sulfur heteroatomic derivatives were positively identified for the first time. Quantitative analysis of target PAHs revealed that total PAH concentrations in coking wastewaters were in the range of 98.5±8.9 to 216±20.2 μg/L, with 3-4-ring PAHs as dominant compounds. Calculation of daily PAH output from four plant subunits indicated that PAHs in the coking wastewater came mainly from ammonia stripping wastewater.Coking wastewater treatment processes played an important role in removing PAHs in coking wastewater, successfully removing 92 % of the target compounds. However, 69 weakly polar compounds, including PAH isomers, were still discharged in the final effluent, producing 8.8±2.7 to 31.9±6.8 g/day of PAHs with potential toxicity to environmental waters. The study of coking wastewater herein proposed can be used to better predict improvement of coke production facilities and treatment conditions according to the identification and removal of PAHs in the coke plant as well as to assess risks associated with continuous discharge of these contaminants to receiving waters.

Performance and microbial community composition in a long-term sequential anaerobic-aerobic bioreactor operation treating coking wastewater

“…3 and 4) as compared to those in the sludge treating municipal sewage ) and other industrial wastewaters (Ibarbalz et al 2013) that may be credited to complex nature of CWW as shown in previous literatures (Zhang et al 2013;Zhao et al 2014;Hou et al 2015) and also in this study. Interestingly, bacterial and fungal community compositions in the sludge were in accordance to bioreactor performance removing majority of organic and toxic pollutants.…”

“…In the aerobic sludge, the high abundances of Thiobacillus, Comamonas, Diaphorobacter, Ottowia, and Weeksella (Table S8), which reportedly degrade several phenol and SCN − compounds (Felföldi et al 2010;Beller et al 2006;Klankeo et al 2009;Yuste et al 2000), were in accordance with the significant removal of pollutants in the final effluent. As referred in Table S8, the significant presence of PAHdegrading bacteria like Comamonas (Goyal and Zylstra 1996) and Diaphorobacter (Klankeo et al 2009) indicated the removal of corresponding pollutants in aerobic sludge leading to detoxification of CWW (Zhang et al 2013). The high abundances of NHC-degrading bacteria Brevundimonas, Sphingopyxis, Sphingosinicella Stolz 2009;Baik et al 2013), and Comamonas (Felföldi et al 2010;Zhang et al 2015) also tallied with the complete disappearance of NHCs in the final effluent in this study.…”

“…Coking wastewater (CWW) generated during coke production has garnered wide attention due to its mixture of diverse organic contaminants that are hazardous to ecosystems and human health (Song et al 2013;Zhang et al 2013;Felföldi et al 2010;Zhao et al 2014;Hou et al 2015). CWW is generally treated by biological methods such as conventional activated sludge processes (Vazquez et al 2006;Maranon et al 2008).…”

“…Despite the toxicity of contaminants like cyanides (CN − ) and phenols (Kim et al 2008;Sharma et al 2012), aerobic activated sludge processes can effectively remove phenol Electronic supplementary material The online version of this article (doi:10.1007/s00253-016-7591-8) contains supplementary material, which is available to authorized users. derivatives, polyaromatic hydrocarbons (PAH), nitrogenous heterocyclic compounds (NHCs), thiocyanate (SCN − ), thiosulfate (Felföldi et al 2010;Vazquez et al 2006;Zhang et al 2013;Bai et al 2009;Sharma and Philip 2015;Shoji et al 2014), releasing sulfate (SO 4 2− ), and ammonia (NH 4 + ) into treated effluent (Staib and Lant 2007). However, aerobic processes require high energy input, generate large volumes of sludge, and do not adapt well to influent fluctuations .…”

Acute toxicity and chemical evaluation of coking wastewater under biological and advanced physicochemical treatment processes

“…China contributed to most of the hard coke production in the world and the discharge of coking wastewater in China was over 1.8 × 10 8 t in 2005 (Wei et al 2007;Zhang et al 1998). Hazardous materials, both the inorganic and organic compounds, especially refractory and inhibitory organics, e.g., phenols, polycyclic aromatic hydrocarbons, pyridine, and indole, are found at high concentrations in coking wastewater (Zhang et al 2013). The pollutants in the coking wastewater may affect all aspects of the environment including water, air, and land and exert significant adverse effects on the ecological environment (Han et al 2011), as such the Chinese government has adopted a series of measures to treat and manage coking wastewater, this includes establishing stricter discharge standards of pollutants for coking chemical industry in 2012 (GB16171-2012).…”