Isolation of two salt-tolerant strains from activated sludge and its COD degradation characteristics from saline organic wastewater

Abstract

The efficient biological treatment of saline wastewater has been limited by the low activities of microorganisms under saline conditions. High salinity poses unbalance osmotic stress across the cell wall and even leads to cell plasmolysis. In this work, we aim to isolate salt-tolerant bacterial strains from activated sludge, and apply them for degrading chemical oxygen demand (COD) of saline organic wastewater. Two salt-tolerant strains were screened and isolated from activated sludge, which was domesticated with salty water for over 300 days. The two strains were identified as Bacillus cereus (strain A) and Bacillus anthracis (strain B) through 16S rRNA sequencing. The degradation characteristics of strain A were explored. The results showed the relative membrane permeability of strain A remained stable under high salt stress, which glycine and proline play an important role to maintain cell osmotic. The protein and soluble sugar amounts of strain were increased by higher salt concentrations. In simulating saline wastewater, the optimum culture temperature, pH, salinity, influent COD concentration and inoculation amount of strain A were 35 °C, 9, 4%, 8000 mg L−1, 6%, respectively. Optimal conditions could provide guidance for the treatment of practical saline wastewater. The linear regression model of each impact factor built based on the result PB experiment revealed that cross-linking time has the most significant influence on COD removal for salt-tolerant strains. It will provide theoretical basis for biological treatment of saline organic wastewater.

Current available treatment technologies for saline wastewater and land‐based treatment as an emerging environment‐friendly technology: A review

“…Also, some of them are insufficient for the diffusion of pollutants (Shatat & Riffat, 2012; M. Wu, Tang, et al, 2013; X. Wu, Du, et al, 2013). Likewise, treatment technologies such as the biological treatment (Cui et al, 2021; Eom et al, 2018; Tomei et al, 2017; Zhou et al, 2020), physicochemical treatments (Liu et al, 2020; Mosquera Corral et al, 2021; Q. Wang et al, 2021) and combined (hybrid) treatments (Song et al, 2018; Panagopoulos, 2021; Xu et al, 2021; H. Zhang, Zhou, et al, 2021), constructed wetlands (CWs) (Lv et al, 2021; Sepúlveda et al, 2020; W. Wang, Wang, et al, 2020; Zhou et al, 2020), zeolite‐based treatments (Alsayed & Ashraf, 2021; Cao et al, 2021), aerobic and anaerobic treatments (Oliveira et al, 2021; Val del Río et al, 2021), and halophilic microorganisms‐assisted treatments (Capodici et al, 2018; Cui et al, 2021; Maharaja et al, 2020) are also adopted for saline wastewater treatment. Treatment and reuse of saline wastewater by CWs has become a common practice in the recent years, because of its low costs, aesthetic values, efficiency, and ecofriendly characteristics over other conventional wastewater treatment methods (Liang, Zhu, Bañuelos, Yan, Shutes, et al, 2017; X. Wang, Zhu, et al, 2020).…”

Optimized Artificial Intelligent Model to Boost the Efficiency of Saline Wastewater Treatment Based on Hunger Games Search Algorithm and ANFIS

“…The proper treatment of such wastewater can secure a considerable portion of fresh water requirements. High salts can be found in various industrial wastewaters, including textiles, medicines, leather goods, fish, meat processing, and marine products [6,7]. Along with contaminated groundwater and wastewater from mining operations and recycling units in the gas and oil industries, salt can also be discovered in significant amounts in the leachate of urban dumpsites [8,9].…”