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. 2016 Feb 12:6:21622.
doi: 10.1038/srep21622.

Combined Effect of Free Nitrous Acid Pretreatment and Sodium Dodecylbenzene Sulfonate on Short-Chain Fatty Acid Production from Waste Activated Sludge

Jianwei Zhao  1   2 , Yiwen Liu  3 , Bingjie Ni  3 , Qilin Wang  3 , Dongbo Wang  1   2   3 , Qi Yang  1   2 , Yingjie Sun  4 , Guangming Zeng  1   2 , Xiaoming Li  1   2
Affiliations

Combined Effect of Free Nitrous Acid Pretreatment and Sodium Dodecylbenzene Sulfonate on Short-Chain Fatty Acid Production from Waste Activated Sludge

Jianwei Zhao et al. Sci Rep. .

Abstract

Free nitrous acid (FNA) serving as a pretreatment is an effective approach to accelerate sludge disintegration. Also, sodium dodecylbenzene sulfonate (SDBS), a type of surfactants, has been determined at significant levels in sewage sludge, which thereby affects the characteristics of sludge. Both FNA pretreatment and sludge SDBS levels can affect short-chain fatty acid (SCFA) generation from sludge anaerobic fermentation. To date, however, the combined effect of FNA pretreatment and SDBS presence on SCFA production as well as the corresponding mechanisms have never been documented. This work therefore aims to provide such support. Experimental results showed that the combination of FNA and SDBS treatment not only improved SCFA accumulation but also shortened the fermentation time. The maximal SCFA accumulation of 334.5 mg chemical oxygen demand (COD)/g volatile suspended solids (VSS) was achieved at 1.54 mg FNA/L treatment and 0.02 g/g dry sludge, which was respectively 1.79-fold and 1.41-fold of that from FNA treatment and sludge containing SDBS alone. Mechanism investigations revealed that the combined FNA pretreatment and SDBS accelerated solubilization, hydrolysis, and acidification steps but inhibited the methanogenesis. All those observations were in agreement with SCFA enhancement.

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Figures

Figure 1
Figure 1
Effect of FNA concentration on SCFA generation from WAS anaerobic fermentation with the combined FNA and SDBS treatment (a) and the fraction of individual SCFA under the optimal condition (b). The dosage of SDBS was 0.02 g/g DS. Results are the averages and their standard deviations of triplicate measurements.
Figure 2
Figure 2. Effect of different treatments on BSA and dextran degradation on 3 d.
The FNA concentration and SDBS dosage were 1.54 mg FNA/L and 0.276 g SDBS/L, respectively. Results are the averages and their standard deviations of triplicate measurements.
Figure 3
Figure 3. Effect of different treatment conditions on the consumption rate of acetate with fermentation time.
The FNA concentration and SDBS dosage were 1.54 mg FNA/L and 0.276 g SDBS/L, respectively. Results are the averages and their standard deviations of triplicate measurements.
Figure 4
Figure 4
Effect of FNA concentration on the variation of NH4+-N (a) and PO43−-P (b) during WAS anaerobic fermentation. Error bars represent standard deviations of triplicate tests.
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