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Quantifying Cyanide Inhibition of Nitrification and Developing Cost-Effective Treatment Processes.

機(jī)譯：量化氰化物對硝化的抑制作用并開發(fā)具有成本效益的處理方法。

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All wastewater treatment plants that operate multiple hearth furnaces (MHF) and are required to nitrify must manage the inhibitory effects of free cyanide (HCN, CN--) in the scrubber return flows due to inhibitory impacts on nitrifying bacteria.;HRSD Boat Harbor Treatment Plant (BHTP) a 25 MGD facility consisting of primary and secondary treatment, employs an anoxic selector process for nitrification and partial denitrification and operates a MHF. There is a desire to improve TN removal performance at BHTP due to an annual mass-based bubble permit limit on a combined discharge from seven HRSD plants, and there are no discharge limitations for ammonia or TKN at BHTP.;Due to a limited footprint, management made the decision of dedicating one aeration tank for sidestream treatment of incinerator scrubber water (SW) for biological oxidation of cyanide, an approach which has been used effectively in several plants around the US and HRSD (Daigger et al., 1998). However when this aeration tank, used as a mainstream biological cyanide treatment process (MBCNTP), was put into service for first time, nitrification was not achieved.;Three 22 L sequencing batch reactors (SBR's) with different configurations were used to investigate the feasibility of sending SW to the head of the plant, dosing with potassium cyanide (KCN) to find the maximum cyanide concentration before inhibition of nitrifying bacteria, determining the dosage rate of ferrous sulfate to form soluble Fe-CN complexes and/or insoluble Fe-CN precipitates, and to investigate if it is feasible to use one aeration tank from the BNR process as a MBCNTP.;After approximately 8 months of operation using SBRs and after performing several jar tests, it was determined that cyanide in the SW was the primary inhibitor, additionally, concentrations above 0.08 mg/L at 20 °C and concentrations above 0.26 mg/L at 28 °C were observed to have a negative impact on nitrification, when operating at 15 days total SRT, 10 days aerobic SRT.;Chemical precipitation of cyanide using ferrous sulfate could be an alternative, however trying to maintain the ideal conditions can be expensive since enough ferrous sulfate must be added to maintain the right Fe-CN ratio and enough sodium hydroxide to increase the pH to optimal conditions.;Additionally, temperatures in the MBCNTP system should be maintained below or at 40 °C to successfully degrade cyanide. Nonetheless, this parameter could be difficult to control with the new MACT 129 regulation, which basically changed the way the incinerators are operated.
機(jī)譯：由于對硝化細(xì)菌的抑制作用，所有使用多個(gè)爐膛爐（MHF）并需要硝化的廢水處理廠都必須控制洗滌塔回流中游離氰化物（HCN，CN--）的抑制作用。工廠（BHTP）是由一級和二級處理組成的25 MGD工廠，采用缺氧選擇器工藝進(jìn)行硝化和部分反硝化，并運(yùn)行MHF。由于對七家HRSD工廠的聯(lián)合排放進(jìn)行了基于質(zhì)量的年度氣泡許可限制，因此希望提高BHTP的TN去除性能，并且對BHTP的氨或TKN沒有排放限制。管理層決定將一個(gè)曝氣池專用于焚化器洗滌器水（SW）的側(cè)流處理，以進(jìn)行氰化物的生物氧化，該方法已在美國和HRSD的多家工廠中得到有效使用（Daigger等，1998）。然而，當(dāng)該曝氣池作為主流生物氰化物處理工藝（MBCNTP）首次投入使用時(shí)，卻無法實(shí)現(xiàn)硝化作用。;使用三個(gè)具有不同配置的22 L順序批處理反應(yīng)器（SBR）來研究可行性將SW送到植物頭部的步驟，在抑制硝化細(xì)菌之前，先加氰化鉀（KCN）以找出最大氰化物濃度，確定硫酸亞鐵形成可溶性Fe-CN絡(luò)合物和/或不溶性Fe-CN的劑量比率沉淀，并研究使用BNR工藝中的一個(gè)曝氣池作為MBCNTP是否可行。;在使用SBR運(yùn)轉(zhuǎn)約8個(gè)月并進(jìn)行幾次罐式測試后，確定SW中的氰化物是主要的抑制劑此外，在15天的操作溫度下，在20°C時(shí)高于0.08 mg / L的濃度和在28°C時(shí)高于0.26 mg / L的濃度對硝化有負(fù)面影響總的SRT，需氧的SRT為10天；使用硫酸亞鐵化學(xué)沉淀氰化物可能是一種替代方法，但是試圖維持理想的條件可能是昂貴的，因?yàn)楸仨毺砑幼銐虻牧蛩醽嗚F來維持正確的Fe-CN比和足夠的氫氧化鈉以將pH值增加到最佳條件。此外，MBCNTP系統(tǒng)中的溫度應(yīng)保持在40°C以下或40°C以成功降解氰化物。盡管如此，使用新的MACT 129法規(guī)可能很難控制該參數(shù)，該法規(guī)從根本上改變了焚燒爐的運(yùn)行方式。

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  • 作者

    Salazar-Benites, Germano M.;

  • 作者單位

    Old Dominion University.;

  • 授予單位 Old Dominion University.;
  • 學(xué)科 Environmental engineering.;Chemical engineering.;Biochemistry.
  • 學(xué)位 M.S.
  • 年度 2017
  • 頁碼 122 p.
  • 總頁數(shù) 122
  • 原文格式 PDF
  • 正文語種 eng
  • 中圖分類 古生物學(xué);
  • 關(guān)鍵詞

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