Removal of pollutants and accumulation of high-value cell inclusions in a batch reactor containing Rhodopseudomonas for treating real heavy oil refinery wastewater

Genomic Insights and Comparative Analysis of Novel Rhodopseudomonas Species: A Purple Non-Sulfur Bacterium Isolated from Latex Rubber Sheet Wastewater

Rhodopseudomonas is recognized for its versatile metabolic capabilities that enable it to effectively degrade pollutants and survive various environmental stresses. In this study, we conducted a genome analysis of Rhodopseudomonas sp. P1 to investigate its genetic potential for wastewater treatment processes. Phylogenetic and genome-relatedness analyses confirmed that strain P1 is genetically distinct from other species within the Rhodopseudomonas genus, establishing it as a novel species. The genome sequences obtained and analyzed focused on genes related to carbon and nutrient removal, photosynthetic capabilities, nitrate and nitrite reduction, and the biodegradation of common wastewater pollutants. The identification of wastewater treatment-related genes followed an extensive review of the existing literature that helped in selecting genes involved in various wastewater treatment mechanisms. The genome of Rhodopseudomonas sp. P1 contains a diverse array of genes involved in carbon and nutrient cycling, pollutant biodegradation, and metal resistance, all of which are crucial for its survival in the complex wastewater environment. Specifically, the strain contains genes responsible for the denitrification, nitrogen fixation, sulfur cycling, and detoxification of toxic metals such as copper and arsenic. These findings highlight the potential application of Rhodopseudomonas sp. P1 in wastewater treatment, particularly in environments contaminated with organic pollutants and heavy metals. However, while the genomic features indicate significant promise, the practical implementation of Rhodopseudomonas sp. P1 in real-world wastewater treatment systems will require further investigation, optimization, and validation to fully harness its potential for sustainable and efficient wastewater treatment.

Application of R. Palustris in simulated wastewater purification and the degradation mechanism of crystal violet

Azo dyes and triphenylmethane dyes poses a large threat to human health, There are many ways to degrade dyes while biodegraded are considered simpler, environmentally friendly, and economical. This study have researched the ability of Rhodopseudomonas palustris (R. palustris) to degrade multiple dyes. In this study, the ability of R. palustris to degrade multiple dyes was investigated. Specifically, the degradation efficiency of R. palustris for crystal violet (CV), malachite green (MG), congo red (CR), as well as COD, inorganic phosphorus, nitro, and nitroso compounds in simulated wastewater was evaluated using colorimetric methods. CV was selected for further analysis, and its intermediate metabolites were characterized using UV-vis spectroscopy, GC-MS, and HPLC-MS. Additionally, the gene expression levels of key enzymes involved in CV degradation were analyzed by RT-PCR, and a potential degradation pathway for CV was proposed. The results demonstrated that the degradation rates of CV, MG, and CR in simulated wastewater reached 97%, 92%, and 58%, respectively. Meanwhile, the degradation rates of COD, inorganic phosphorus, nitro, and nitroso compounds were up to 89.51%, 92.83%, 86.49%, and 85.91%, respectively. The intermediate metabolites of CV degradation by R. palustris included leucocrystal violet, triphenylmethane, and phenol. Notably, the gene expression levels of NADH-QO, NADH-FO, P450, Mett, and Nir were upregulated in the presence of CV. Based on these findings, a potential degradation pathway for CV by R. palustris was proposed: CV undergoes deamination via nitroreductase, followed by triphenylmethane cleavage into benzene and methylbenzene through oxidoreductases. Methylbenzene is then converted to phenol by methyltransferase. Although a potential degradation pathway for CV by R. palustris has been proposed, it remains a hypothesis. It still need to comprehensively investigate the genes associated with dye degradation in R. palustris through transcriptomics and to further validate the crystal violet degradation pathway proposed in this study.

Removal and recovery of nitrogen from anaerobically treated leachate based on a neglected HNAD nitrogen removal pathway: NH3 stripping

The heterotrophic nitrification aerobic denitrification (HNAD) process can withstand the environment with high NH4+-N concentration and complex components, and has the potential to be an effective scheme for nitrogen removal of anaerobically treated leachate from municipal solid waste incineration plant. But its mechanism is still unclear and the NH3 stripping process has received little attention. At the same time, the high concentration of NH4+-N in the anaerobically treated leachate also has great recycling potential. In this study, typical HNAD microorganisms were enriched and used for nitrogen removal from anaerobically treated leachate. A one-step system with a total nitrogen removal ratio of more than 98 % was constructed. Isotopic labeling experiments showed that nitrogen was not the main product. The important role of NH3 stripping in the HNAD system was defined, and 46.63 % nitrogen was recovered on this basis.

A novel physical-biochemical treatment of refinery wastewater

As of 2022, China has achieved a crude oil processing capacity of 918 million tons, leading to a notable escalation in the production of refinery wastewater. The composition of refinery wastewater is intricate and diverse, posing a substantial challenge to its treatment. In order to facilitate appropriate discharge or reuse, an exhaustive separation process is imperative for refinery wastewater. Conventional pre-treatment processes typically employ inclined plate separators and dissolved air flotation (DAF) for the removal of oil and suspended solids (SS), while sequencing batch reactor (SBR), oxidation ditch, or biological aerated filter (BAF) are employed for the biological treatment process. However, these approaches encounter challenges such as a large spatial footprint, suboptimal treatment efficiency, and high energy consumption. In response to these challenges, this study introduces a novel integrated apparatus consisting of a high-efficiency oil remover (HEOR), coalescence oil remover (COR), and an airlift-enhanced loop bioreactor (AELR). A pilot-scale test was conducted to evaluate the performance of this integrated system in practical field applications. The pilot-scale tests reveal that, without the addition of chemical agents, the petroleum removal efficiency of "HEOR + COR" system was 1.2 times that of DAF. Compared with the SBR system, AELR's volume loading was increased by 1.56 times. The effluent quality achieved in the pilot-scale tests attained parity with that the original process. The "HEOR + COR + AELR" system exhibited energy and carbon emissions reduction of 28% and 30% compared to the "DAF + SBR" system, respectively. Therefore, the operating costs was reduced by approximate 1 Chinese Yuan (CNY) per ton of treated water. This technological advancement serves as a valuable reference for the implementation of low-carbon treatment of refinery wastewater.