The wastewater from the olefin cracking plant effect the nitrifying bacteria of sludge

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Dear all,

(1) In order to reclaim the wastewater (the conductivity is near 1,000 us/cm, can supply for cooling tower) from the olefin cracking plant, we test in Lab. to evaluate the COD react to CO2 and Total Kjeldahl nitrogen (TKN) react to NO3 or N2, our test is blend 10%/22% wastewater from olefin cracking plant (0% is the blank) .

(2) The COD conversion rate of 10%/22% we blend is about 85~87 %, near the blank (90 %),the TKN conversion rate of 10%/22% we blend is about 46%, much lower than the blank(74%).

(3) Could you kindly tell us the reason? we guess some impurity from the olefin cracking plant to effect the nitrifying bacteria, and lower the conversion rate of sludge. Could someone offer the references, thanks.

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2 Answers

  1. ANswer from CHAT GPT- OPEN AI: 

    The issue of olefin cracking plant wastewater affecting nitrifying bacteria in sludge, leading to a lower conversion rate of Total Kjeldahl Nitrogen (TKN) to NO3, can be complex. Let’s delve into the possible reasons and supporting references in detail.

    Possible Reasons for Lower TKN Conversion Rate

    1. Presence of Toxic Impurities:

      • Olefin cracking plant wastewater may contain various organic and inorganic impurities, such as phenols, sulfides, heavy metals, and other hydrocarbons, which can be toxic to nitrifying bacteria. These impurities may inhibit the activity of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), which are crucial for the nitrification process.

    2. Inhibition of Nitrifying Bacteria:

      • Specific compounds in the wastewater might inhibit the enzymes involved in the nitrification process. For example, phenolic compounds are known to inhibit ammonia monooxygenase (AMO), an enzyme crucial for ammonia oxidation by AOB.

    3. Competitive Inhibition and Increased Organic Load:

      • The presence of high concentrations of organic compounds in the olefin cracking plant wastewater might increase the competition between nitrifying bacteria and heterotrophic bacteria for oxygen and space within the sludge. Since heterotrophs generally grow faster than nitrifiers, this competition can lead to a lower nitrification rate.

    4. Changes in Microbial Community Structure:

      • The introduction of olefin cracking plant wastewater can alter the microbial community structure of the activated sludge. Nitrifying bacteria are sensitive to changes in environmental conditions and the presence of specific inhibitory substances, leading to a decline in their population and activity.

    References Supporting the Impact of Wastewater on Nitrifying Bacteria

    1. Impact of Wastewater Composition and Seasonal Dynamics:

      • The composition of the wastewater and seasonal changes can significantly impact the performance of nitrifying bacteria in activated sludge systems. For instance, a study highlighted the influence of wastewater characteristics and seasonal dynamics on the activated sludge microbiome, which in turn affects nitrification efficiency (source: Water Research journal).

    2. Growth Rate of Nitrifying Bacteria vs. Heterotrophs:

      • Nitrifying bacteria have slower growth rates compared to heterotrophs. In systems with high organic loads or specific inhibitory substances, heterotrophs can outcompete nitrifiers, leading to reduced nitrification performance. Research has shown that maintaining a higher growth rate of nitrifiers relative to heterotrophs is crucial for effective nitrification (source: Environmental Science & Technology journal).

    3. Inhibition by Specific Compounds:

      • Studies have documented that specific impurities, such as phenolic compounds and heavy metals, present in industrial wastewater can inhibit nitrification processes. These substances can affect enzyme activity and the overall health of nitrifying bacteria (source: Journal of Hazardous Materials ).

    Addressing the Issue

    To address the observed lower TKN conversion rate, the following steps could be taken:

    1. Comprehensive Wastewater Analysis:

      • Conduct a detailed analysis of the wastewater from the olefin cracking plant to identify specific inhibitory compounds and their concentrations.

    2. Toxicity Assessment:

      • Perform toxicity assays to determine the impact of identified impurities on nitrifying bacteria.

    3. Microbial Community Monitoring:

      • Monitor changes in the microbial community structure of the activated sludge to understand how the introduction of olefin cracking plant wastewater affects nitrifiers.

    4. Pre-treatment of Wastewater:

      • Implement pre-treatment processes to remove or reduce toxic impurities from the olefin cracking plant wastewater before it is introduced to the activated sludge system.

    5. Optimizing Operating Conditions:

      • Adjust operational parameters, such as aeration rate and sludge retention time, to favor the growth and activity of nitrifying bacteria.

    By addressing these factors, it may be possible to mitigate the negative impact of olefin cracking plant wastewater on nitrifying bacteria and improve the TKN conversion rate in the sludge.

  2. Answer from You.com : 

    Understanding the Impact of Olefin Cracking Plant Wastewater on Nitrifying Bacteria in Sludge

    Based on the information provided, it seems that the wastewater from the olefin cracking plant may be affecting the nitrifying bacteria in the sludge, leading to a lower conversion rate of Total Kjeldahl nitrogen (TKN) to NO3. Let's explore the possible reasons and references related to this issue. Possible Reasons for Lower TKN Conversion Rate: The lower TKN conversion rate of the blended wastewater from the olefin cracking plant compared to the blank (74%) could be attributed to the presence of impurities from the olefin cracking plant affecting the nitrifying bacteria and subsequently lowering the conversion rate of the sludge

    . References Supporting the Impact of Wastewater on Nitrifying Bacteria:

    • The activated sludge microbiome is influenced by various factors, including the composition of the wastewater and seasonal dynamics, which can impact nitrification performance 

       

    • Studies have shown that the growth rate of nitrifying bacteria must be higher than that of heterotrophs in the system, and the presence of impurities or specific conditions in the wastewater can affect nitrification and denitrification processes 

       

    It's important to consider the specific impurities or components present in the wastewater from the olefin cracking plant that may be inhibiting the nitrifying bacteria. Further investigation and analysis of the wastewater composition and its impact on the sludge microbiome may provide valuable insights into addressing the observed lower TKN conversion rate.