2.1. Advanced oxidation processes (AOPs) and electrocoagulation processes
AOPs in general are being well known for their capacity in removing many organic contaminants. AOPs are able to convert recalcitrant pollutants into biodegradable intermediates that can be degraded in a biological process. However, it is negatively affected by suspended solids that act as scavengers toward hydroxyl radicals which are formed by ozone decomposition in water. In this view, MBR offers unique opportunities in terms of suspended solid-free effluent and thus enhance the efficiency of ozonation. AOPs can be used as pre- or post-biological treatment of wastewater. Pre-treatments have been proven useful in the case of wastewater which containing small amounts of biodegradable organics and large amount of recalcitrant compounds. In contrast, post-treatment results are preferable when biodegradable compounds are greater than that of recalcitrant compounds [18].
Mascolo et al. [19] studied the effective organic degradation from pharmaceutical wastewater by an integrated process of MBR and ozonation. The reactor was set up by placing the ozonation reactor in the recirculation stream of the MBR effluent. The organic compound (acyclovir) in the effluent was removed up to 99% from the MBR step and ozonation allowed to further remove 99% of the MBR effluent. For several organics identified in the wastewater, the efficiency of the MBR treatment improved from 20% to 60% when the ozonation was placed in the recirculation system. This study found out that MBR-ozonation system gave results comparable to those obtained by the two separated treatment systems. In contrast, López et al. [20] studied the integration of solar photo catalysis followed by MBR for pesticide degradation. The permeate obtained in the coupled system was ready-to-use high quality water, with the absence of pesticides, absence of solids, and turbidity values (NTU) below 0.5. The results demonstrated that this system is able to treat the pesticide mixture without adding carbon source. Laera et al. [18] investigated integration of MBR with either ozonation or UV/H2O2 process by placing chemical oxidation in the recirculation stream of the MBR. The study reported the removal of synthetic wastewater contained nalidixic acid which was used in treating urinary tract infections. MBR alone is not efficient in removing the degradation products of the nalidixic acid as those compounds would pass through the MBR. However, integration of ozonation completely removed the degradation products in the step of chemical oxidation. An integrated thermophilic submerged aerobic membrane bioreactor (TSAMBR) and electrochemical oxidation technology using Ti/SnO2–Sb2O5–IrO2 electrode was developed for treatment of pulp and paper effluent [21]. The integrated oxidation processes completely decolorize the effluent and further enhance the removal of COD. The high quality effluent can be produced through the integrated process and has the potential for the direct reuse in the mill. Giacobbo et al. [22] investigated the integrated MBR-photoelectrooxidation (MBR–PEO) for tannery wastewater treatment. The MBR is responsible for the remaining biochemical oxygen demand (BOD) removal, while the refractory matter (contributed to COD) is removed by PEO. The treated wastewater could be recycled for the tanning and re-tanning steps. Fouling does not penetrate in the membrane pores and can perform well after 360 h of work without membrane cleaning. Lamsal [23] examined the fouling in nanofiltration membrane and explored various pre-treatment strategy to reduce the fouling process. The author found out that AOP pre-treatments with NF membrane resulted in an improved permeate flux but not permeate quality of the NF membrane. Merayo et al. [24] stated that higher COD removal was achieved treating the pulp mill effluent from the recycled MBR followed by AOPs. The remaining recalcitrant compounds could be more efficiently ozonized when the effluent was treated with MBR.
2.1. กระบวนการออกซิเดชัน (AOPs) และกระบวนการ electrocoagulation ขั้นสูงAOPs ทั่วไปกำลังรู้จักกันดีสำหรับกำลังการผลิตในการเอาสารปนเปื้อนอินทรีย์มากขึ้น AOPs จะแปลงสารมลพิษ recalcitrant เป็น intermediates สลายที่สามารถเสื่อมโทรมในกระบวนการทางชีวภาพ อย่างไรก็ตาม มันจะส่งผลกระทบ โดยของแข็งระงับซึ่งทำหน้าที่เป็น scavengers อนุมูลไฮดรอกซิลซึ่งก่อตั้ง โดยแยกส่วนประกอบของโอโซนในน้ำต่อ ในมุมมองนี้ MBR ให้โอกาสเฉพาะในน้ำแข็งฟรีระงับ และเพิ่มประสิทธิภาพของกัมมันต์ดังนั้น สามารถใช้ AOPs เป็นก่อน หรือหลังชีวภาพบำบัดน้ำเสีย รักษาก่อนได้รับการพิสูจน์ประโยชน์ในกรณีที่น้ำเสียซึ่งประกอบด้วยเงินสลายอินทรีย์และสารประกอบ recalcitrant จำนวนมาก ในทางตรงกันข้าม ผลการรักษาหลังเป็นกว่าเมื่อสลายสารมากกว่าของสารประกอบ recalcitrant [18]Mascolo et al. [19] studied the effective organic degradation from pharmaceutical wastewater by an integrated process of MBR and ozonation. The reactor was set up by placing the ozonation reactor in the recirculation stream of the MBR effluent. The organic compound (acyclovir) in the effluent was removed up to 99% from the MBR step and ozonation allowed to further remove 99% of the MBR effluent. For several organics identified in the wastewater, the efficiency of the MBR treatment improved from 20% to 60% when the ozonation was placed in the recirculation system. This study found out that MBR-ozonation system gave results comparable to those obtained by the two separated treatment systems. In contrast, López et al. [20] studied the integration of solar photo catalysis followed by MBR for pesticide degradation. The permeate obtained in the coupled system was ready-to-use high quality water, with the absence of pesticides, absence of solids, and turbidity values (NTU) below 0.5. The results demonstrated that this system is able to treat the pesticide mixture without adding carbon source. Laera et al. [18] investigated integration of MBR with either ozonation or UV/H2O2 process by placing chemical oxidation in the recirculation stream of the MBR. The study reported the removal of synthetic wastewater contained nalidixic acid which was used in treating urinary tract infections. MBR alone is not efficient in removing the degradation products of the nalidixic acid as those compounds would pass through the MBR. However, integration of ozonation completely removed the degradation products in the step of chemical oxidation. An integrated thermophilic submerged aerobic membrane bioreactor (TSAMBR) and electrochemical oxidation technology using Ti/SnO2–Sb2O5–IrO2 electrode was developed for treatment of pulp and paper effluent [21]. The integrated oxidation processes completely decolorize the effluent and further enhance the removal of COD. The high quality effluent can be produced through the integrated process and has the potential for the direct reuse in the mill. Giacobbo et al. [22] investigated the integrated MBR-photoelectrooxidation (MBR–PEO) for tannery wastewater treatment. The MBR is responsible for the remaining biochemical oxygen demand (BOD) removal, while the refractory matter (contributed to COD) is removed by PEO. The treated wastewater could be recycled for the tanning and re-tanning steps. Fouling does not penetrate in the membrane pores and can perform well after 360 h of work without membrane cleaning. Lamsal [23] examined the fouling in nanofiltration membrane and explored various pre-treatment strategy to reduce the fouling process. The author found out that AOP pre-treatments with NF membrane resulted in an improved permeate flux but not permeate quality of the NF membrane. Merayo et al. [24] stated that higher COD removal was achieved treating the pulp mill effluent from the recycled MBR followed by AOPs. The remaining recalcitrant compounds could be more efficiently ozonized when the effluent was treated with MBR.
การแปล กรุณารอสักครู่..