ORP-based膨脹顆粒污泥床處理含硫酸鹽有機廢水之性能及動力

Performance and kinetics of ORP-based EGSB reactor treating sulfate-laden organic wastewater

陳信逸(Hsin-Yi Chen)

指導教授 ： 黃汝賢 ； 周信賢

崑山科技大學/工程學院/環境工程研究所/碩士(2009年)

摘要

本研究除了建立涵蓋有H2S對厭氣菌產生抑制效應之膨脹顆粒污泥床(EGSB)反應器動力模式/經驗模式及實驗驗證模式之適用性外，亦以一組ORP-based EGSB反應器(內部純氧曝氣；操作溫度 = 35C，表面流速us = 4.0 m/h)操控在COD/SO42-進流比0.5及ORP -410 mV及一組傳統EGSB反應器(未進流SO42-，操作溫度 = 35C，us = 4.0 m/h，ORP = -400 mV)分別強化培養硫酸鹽還原菌(SRB)及甲烷菌(MB)並藉以探求SRB及MB之intrinsic及apparent動力參數，另以兩組ORP-based EGSB反應器分別操控在COD/SO42-進流比1.1(反應器A)及3.0(反應器B)處理含硫酸鹽有機廢水，有機負荷率由4.0陸續提高至6.0及9.0 kg COD/m3-d，探討其效能、生物顆粒特性、 SRB與MB之生物分率及動力學。
ORP-based EGSB反應器A及反應器B (有機負荷率4.0、6.0及9.0 kg COD/m3-d)之ORP分別操控在-410、-420、-450 mV(相對於未內部純氧曝氣之-432、-446及-478 mV)及-390、-400、-425 mV(相對於未內部純氧曝氣之-411、-425及-450 mV)下，出流水H2S濃度皆隨著有機負荷之提高而增加，反應器A出流水H2S濃度(148~408 mg S/L)則明顯高於反應器B者(33~132 mg S/L)，雖有機負荷率已高達9.0 kg COD/m3-d，乙酸去除率仍在98.6%以上，顯示ORP-based EGSB反應器可降低H2S濃度，並有利於高負荷之操作。此外，生物顆粒之比重、粒徑及生物密度皆隨著有機負荷率之提高而增加；在相同有機負荷率操作下，反應器A (COD/SO42-進流比1.1)之生物顆粒粒徑大於反應器B (COD/SO42-進流比3.0)者，但反應器A之顆粒比重、生物密度則小於反應器B者。SRB及MB之生物分率不受有機負荷率之影響，但反應器A之SRB分率為0.73~0.75，顯示SRB為優勢菌群，而反應器B之MB分率0.75~0.77，顯示MB為優勢菌群，而由系統操作所得之水質數據，以硫酸鹽還原反應之化學計量式所得反應器A之SRB對乙酸去除之貢獻度為0.56~0.60明顯高於反應器B之0.20~0.21。
由求得之SRB與MB intrinsic及apparent動力參數發現，kSR (2.1 mg acetate/mg VSS-d)和kSR’(1.79 mg acetate/mg VSS-d)皆大於kM (1.58 mg acetate/mg VSS-d)和kM’(1.38 mg acetate/mg VSS-d)；Ks,M (10 mg acetate/L)和Ks,M’ (15 mg acetate/L)皆小於Ks,a (32 mg acetate/L)和Ks,a’ (35 mg acetate/L)，意謂著MB對有機物之親和性較SRB者大；KI,M (266 mg H2S/L)和KI,M’ (476 mg H2S/L)皆小於KI,SR (305 mg H2S/L)和KI,SR’ (591 mg H2S/L)，故可知MB較SRB更容易受H2S之抑制。由於Intact granules 之內質傳阻抗，致使apparent kSR’及kM’小於intrinsic kSR及kM。將本研究ORP-based EGSB反應器各試程之操作條件、物理參數及生物動力參數代入動力模式及經驗模式求得之乙酸去除率及硫酸鹽還原率之模擬值與實驗值之誤差分別在±1.0及±10.3%內，且動力模式與經驗模式模擬值之間的差異百分比亦僅2.3%，故動力模式及經驗模式皆可適用於EGSB反應器之功能設計。

關鍵字

ORP-based膨脹顆粒污泥床 ； 內部純氧曝氣 ； COD/SO42-進流比；硫酸鹽還原菌；甲烷菌；H2S之抑制效應 ； 污泥顆粒特性 ； 動力及經驗模式 ； 模式實驗驗證

並列摘要

A kinetic model and empirical model for the EGSB reactor that take into account the inhibiting effect of free hydrogen sulfide (H2S) on bacterial groups is formulated and validated by experiments. Meanwhile, One ORP-based EGSB reactor (with internal oxygenation; operating temperature = 35C, superficial velocity us = 4.0 m/h) maintained at the influent COD/SO42- ratio of 0.5 and ORP of -410 mV as well as one conventional EGSB reactor (without adding SO42-; operating temperature = 35C, us = 4.0 m/h, ORP = -400 mV) were respectively used for the enrichment of sulfate-reducing bacteria (SRB) and methanogenic bacteria (MB) and thereby used for the determination of their intrinsic and apparent kinetic parameters. To investigate the treatment performance, granule characteristics, mass fractions of SRB and MB and reaction kinetics, two ORP-based EGSB reactors treating sulfate-laden organic wastewater were respectively maintained at the influent COD/SO42- ratios of 1.1 (reactor A) and 3.0 (reactor B) but with successive increasing organic loading rate from 4.0 to 6.0 and 9.0 kg COD/m3-d.
When the reactors A and B (organic loading rates of 4.0, 6.0, and 9.0 kg COD/m3-d) were respectively maintained at the operating ORP levels of -410, -420, -450 mV (corresponding to ORP values without internal oxygenation: -432, -446, -478 mV) and -390, -400, -425 mV (corresponding to ORP values without internal oxygenation: -411, -425, -450 mV), the H2S effluent concentration increased with increasing organic loading rate; the H2S effluent concentration in the reactor A (148–408 mg S/L) was remarkably higher than that in the reactor B (33–132 mg S/L); the COD removal efficiency still reached to 98.6% even at the organic loading rate of as high as 9.0 kg COD/m3-d, indicating that the ORP-based EGSB reactor can decrease H2S concentration and thereby benefit its operation at a high organic loading rate. In addition, the granule’s specific gravity, granule diameter, and microbial density increased with increasing organic loading rate; at the same organic loading rate, the granule diameter at the reactor A (influent COD/SO42- ratios of 1.1) was larger than that at the reactor B (influent COD/SO42- ratios of 3.0) whereas the granule’s specific gravity and microbial density at the reactor A were smaller than those at the reactor B. The organic loading rate did not affect the mass fractions of SRB and MB. The mass fraction of SRB determined from the reactor A ranged from 0.73 to 0.75, indicating that SRB out-competed MB for bacterial growth; the mass fraction of MB determined from the reactor B ranged from 0.75 to 0.77, indicating that MB out-competed SRB for bacterial growth.
The estimated intrinsic and apparent kinetic parameters kSR (2.1 mg acetate/mg VSS-d) and kSR’(1.79 mg acetate/mg VSS-d) were greater than kM (1.58 mg acetate/mg VSS-d) and kM’(1.38 mg acetate/mg VSS-d); Ks,M (10 mg acetate/L) and Ks,M’ (15 mg acetate/L) were smaller than Ks,a (32 mg acetate/L) and Ks,a’ (35 mg acetate/L), implying that the affinity of organics to MB was higher, compared with SRB; KI,M (266 mg H2S/L) and KI,M’ (476 mg H2S/L) were smaller than KI,SR (305 mg H2S/L) and KI,SR’ (591 mg H2S/L), indicating that H2S imposed a greater inhibiting effect on MB; apparent kSR’ and kM’ were smaller than intrinsic kSR and kM, showing that internal mass transfer resistance occurred in intact granules. By inserting operating conditions and physical and biological parameter values into the kinetic and empirical models, the calculated acetate removal efficiency and sulfate removal efficiency were ±1.0 and ±10.3% deviated from the experimental acetate removal efficiency and sulfate removal efficiency, respectively. The simulated removal efficiency by using the kinetic model was only 2.3% deviated from that by using the empirical model. Accordingly, the proposed kinetic and empirical models can be properly used for function design of the ORP-based EGSB reactor.

並列關鍵字

ORP-based EGSB reactor ； internal oxygenation ； influent COD/SO42- ratio ； sulfate-reducing bacteria ； methanogenic bacteria ； H2S-inhibiting effect ； granule characteristics ； kinetic and empirical models ； model validation

參考文獻

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