ADVERTISEMENT

Temperature Has A Significant Influence On The Production Of SMP-Based Dissolved Organic Nitrogen (DON) During Biological Processes

Traditionally, activated sludge has been the most commonly used biological process for municipal wastewater treatment. Soluble microbial products (SMPs) formed by microorganisms constitute a wide range of residual organic matter in biological wastewater treatment systems. Their presence is related to the removal performance of treatment systems and safe wastewater reuse. Among a variety of process parameters, temperature shows the most significant effect on SMP formation in activated sludge systems.

Most of the previous studies focused on the characterization of SMP-based dissolved organic carbon (SDOC) at different temperatures, and there are few reports on SMP-based dissolved organic nitrogen (SDON). Additionally, some nitrogenous organics have been identified as important parts of SMPs. Moreover, DON in wastewater is responsible for membrane fouling, leads to cultural eutrophication, and serves as a precursor to several disinfection byproducts. Accordingly, the need for a better understanding of the effect of temperature on SMPs characterization in an activated sludge system with special emphasis on SDON has become increasingly apparent.

ADVERTISEMENT

Recently, a team of researchers led by Professor Hongqiang Ren from the State Key Laboratory of Pollution Control and Resource Reuse at Nanjing University evaluated the effect of different temperatures (8 °C, 15 °C, and 25 °C) on the chemical characterization of SDON in an activated sludge system. It emphasized the importance of SDON control during biological treatment processes at a low temperature with the purpose of reducing the potential effects of SMPs induced to the aquatic environment.

Figure courtesy Haidong Hu

Results showed that effluent SDON concentration ranged from 0.91 mg/L to 1.30 mg/L, and the low-temperature conditions (8 °C and 15 °C) resulted in the increase of SDON concentration in the activated sludge system. Fluorescence excitation-emission matrices coupled with parallel factor analysis (EEM-PARAFAC) and Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) were used to analyze the fluorescent components and molecular characteristics of SDON at different temperatures.

The results showed that the production of SDON at 8 °C and 15 °C exhibited more labile than that at 25 °C. This was also confirmed by the algal bioassay experiment. The SDON bioavailability at 25 °C, 15 °C, and 8 °C were 55.3 ± 4.1%, 61.5 ± 6.6%, and 65.8 ± 3.0%, respectively, indicating that SDON produced at low temperatures is more bioavailable and more susceptible to promote microorganism growth. Interestingly, the principal component analysis (PCA) results showed that the chemical characterization of SDON was different from SDOC at different temperatures. In these cases, the mere measurement of the DOC is not sufficient for understanding the effect of temperature on SMP production in activated sludge systems.

Overall, this study focused on the effect of temperature on SMPs characterization in an activated sludge system with special emphasis on SDON. The results of this study provided an important theoretical basis for SDON control during biological processes at a low temperature, and it is of practical significance to improve the water quality of municipal wastewater treatment plants. The work is currently published in the research journal Water Research.

ADVERTISEMENT

These findings are described in the article entitled Effect of temperature on the characterization of soluble microbial products in activated sludge system with special emphasis on dissolved organic nitrogen, recently published in the journal Water Research (Water Research 162 (2019) 87-94). This work was conducted by Haidong Hu, Yuanji Shi, Kewei Liao, Haijun Ma, Ke Xu, and Hongqiang Ren from Nanjing University.

Comments

READ THIS NEXT

Climate Change Causes Molecular-Level Stress Responses

Anemones are abundant in an acidified ocean. But are they thriving? New genomics research shows that ocean acidification puts these […]

The Rise Of Hand Injuries In Low- And Middle-Income Countries

The hand is the visible part of the brain. – Immanuel Kant The hands are an essential part of human […]

Annihilation And Creation Of Relative Equilibria Around Minor Celestial Bodies

Relative equilibria of asteroids, comets, and satellites of planets are important dynamical characteristic around these minor celestial bodies. Most minor celestial […]

Researchers Use Gene Editing To Remove Fatal Blood Disorder From Embryo

It would be an understatement to say that there are many diseases that humans are facing every day. Some of […]

Evidence For Glaciation Found In Alba Mons Region Of Mars

Climatic conditions and accompanying glacial/periglacial processes have been suggested to vary on Mars during the Late Amazonian epoch (~1.0 Ga […]

World Health Officials Stunned By US Resistance To Breast Feeding

At the World Health Assembly which took place this spring, a resolution intended to encourage the use of breast feeding […]

Typology, Machine Learning, And The Study Of Archaeological Artifacts

Published by Norman MacLeod The Natural History Museum, Cromwell Road, London, SW7 5BD, UK These findings are described in the […]

Science Trends is a popular source of science news and education around the world. We cover everything from solar power cell technology to climate change to cancer research. We help hundreds of thousands of people every month learn about the world we live in and the latest scientific breakthroughs. Want to know more?