Elimination of aromatic surfactants from municipal wastewaters: comparison of conventional activated sludge treatment and membrane biological reactor

Abstract

Behaviour of anionic surfactants of linear alkylbenzene sulphonates (LAS) type and non-ionic surfactants of nonylphenol polyethoxylate (NPnEO) type was studied in the conventional mechanical/biological sewage treatment plant (STP) as well as using a membrane biological reactor (MBR). LAS and NPnEO were determined using high performance liquid chromatography (HPLC) equipped with spectrofluorimetric detection. Liquid chromatography/tandem mass spectrometry (LC/MS/MS) was used for identification and quantification of stable metabolites, including nonylphenol (NP), nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO) and nonylphenoxy carboxylic acids (NPnEC). The study showed that aromatic surfactants belong to the most prominent constituents in the examined municipal wastewaters with typical LAS and NPnEO concentrations of 2-10 mg/L and 0.1-0.5 mg/L, respectively. The removal of aromatic surfactants in conventional STP showed well-known features reported in the literature, including an efficient microbial transformation of the parent molecules and formation of stable metabolic products. The elimination efficiency of aromatic surfactants using the MBR unit was higher than that in the conventional STP, while the composition of recalcitrant nonylphenolic residues in the effluent seems to be ecotoxicologically more favourable due to the lower contributions of the lipophilic metabolites.

Factors affecting the removal of organic micropollutants from wastewater in conventional treatment plants (CTP) and membrane bioreactors (MBR)

“…Satisfying degradation of investigated compounds was registered at high SRT of 30 d. In the same study it was shown that no significant difference is observed between the MBR and CTP in term of degradation performances. Similar observation on the removal of NP and BPA was described by Ivashechkin et al (2004a) during the operation of MBR and CTP processes at SRTs of 12 and 25 d. The high removal efficiency (95%) associated to the operation of high SRT in MBR was confirmed as well by Terzic et al (2005) concerning the removal of NPnEO from wastewater. Joss et al (2004) studied the E1, E2, EE2 degradation in batch experiment using sludge from CTP with SRT of 11 d and MBR with 30 d. For the natural estrogens E1 and E2, degradation activity seemed to be higher in MBR than in CTP by a factor of 2-3 with the respect to the applied SRT.…”

“…The removal of NPnEO and LAS from municipal wastewater was investigated (Terzic et al 2005). The results of this study showed removal efficiency up to 95% and the efficacy was in fact improved when the temperature in the treatment system varied from 3 to 30°C.…”

“…Degradation and partitioning behaviour have also been reported to be a function of the polarto-non polar group ratio of the molecule (Rutherford et al 1992), the presence of aromatic moieties (Chiou et al 1998), and the organic carbon content (Yamamoto et al 2003) which characterize the molecule. Linear alkylbenzene sulphonates (LAS) with long alkyl chain were preferentially adsorbed to the sludge matrix, while the short homologues of this anionic surfactant were found in the effluent in a comparative study in CTP and MBR (Terzic et al 2005). The chemical structure of alkyl chain of NP and LAS is responsible for completely different biodegradation pathways.…”

Distribution and Removal of Nonylphenol Ethoxylates and Nonylphenol from Textile Wastewater—A Comparison of a Cotton and a Synthetic Fiber Factory in Vietnam

“…• Extended SRT as an Essence of Microbial Development and Biomass Quality A complete biotransformation of short-chain NPEOs, as aforementioned, may require a specialized microbial inoculum that could be enriched in an elevated SRT system [81,105,110,141]. According to Cirja et al [81], microbial communities including nitrifying bacteria are able to acclimate and develop at the SRTs of longer than 8 days.…”

Caracterização de contaminantes presentes em sistemas de tratamento de esgotos, por cromatografia líquida acoplada à espectrometria de massas tandem em alta resolução

“…Como exemplo, os alquilbenzenos sulfonados de cadeia linear, conhecidos como LAS, apresentam longas cadeias alquídicas e, por isso, são preferencialmente encontrados adsorvidos no lodo (biomassa aeróbia ou anaeróbia); ao passo que os homólogos menores deste surfactante aniônico se encontram em maior concentração no efluente. 18 Dessa forma, efluentes de estações de tratamento de esgoto podem conter uma variedade de compostos orgânicos, e como o efluente tratado é, muitas vezes, despejado em mananciais de água potável, a poluição desta com contaminantes orgânicos é de grande preocupação. 19 Há vários estudos, feitos em outros países, mostrando que sistemas de tratamento biológico de esgotos não conseguem remover completamente compostos estrogênicos (ex., estradiol, estrona, etinilestradiol) capazes de alterar as funções endócrinas de animais aquáticos.…”