Wastewater treatment method and wastewater treatment system

Abstract

This invention provides a wastewater treatment method and system. The wastewater treatment method includes: a sulfide and thiosulfate generation step, a denitrification anaerobic ammonia oxidation step, and a nitrate supply step, wherein the wastewater generated by the nitrate supply step and / or the denitrification anaerobic ammonia oxidation step is used as effluent. This invention provides an economical and effective integrated water treatment process and system that can couple anaerobic ammonia oxidation.

Description

Technical Field

[0001] This invention relates to the field of environmental protection, and in particular to a wastewater treatment method and system. Specifically, this invention provides an integrated process for sulfate reduction, autotrophic denitrification, nitrification, and anaerobic ammonia oxidation for biological wastewater treatment, as well as a method and system for treating biological wastewater using this process. Background Technology

[0002] Since the 1920s, activated sludge systems have been the most commonly used biological process for wastewater treatment (Ardern and Lockett, 1914). The cost of removing organic matter and nitrogen is high aeration energy consumption (accounting for 45-70% of the energy consumption of WWTP in wastewater treatment plants, Rosso et al., 2008) and a typical long hydraulic retention time (HRT) of 9.4-24.2 hours (Ekama et al., 2020), which results in significant land occupation. Anaerobic ammonium oxidation (anammox) processes require lower aeration energy consumption and do not require organic matter for nitrogen removal; when combined with organic matter collection processes, aeration energy consumption can be reduced by more than 60%, and 90% of organic matter (energy) can be recovered (Wan et al., 2016). Minimizing energy input and maximizing organic matter recovery can enable energy neutrality in wastewater treatment (Kartal et al., 2010). Many attempts have been made to achieve anaerobic ammonium oxidation, such as short-cut nitrification anaerobic ammonium oxidation (PN / A), short-cut denitrification anaerobic ammonium oxidation (PD / A), and sulfur-driven denitrification anaerobic ammonium oxidation (SDA).

[0003] (Deng et al., 2022). However, after more than a decade of effort, achieving anaerobic ammonium oxidation in mainstream environments remains difficult to demonstrate (Wang et al., 2022).

[0004] The known biological wastewater treatment processes include the following.

[0005] - Traditional Activated Sludge Process (CAS). Electrons flow from organic carbon to oxygen in an integrated carbon-nitrogen cycle, namely autotrophic nitrification and heterotrophic denitrification. Figure 2 The details of this biological carbon and nitrogen removal process are as follows: First, in reactor 1, organic carbon is oxidized to carbon dioxide through heterotrophic denitrification, nitrate is reduced to N2, and electrons flow from organic carbon to nitrate; then, in reactor 2, organic matter (calculated as chemical oxygen demand COD) and ammonia nitrogen are oxidized to carbon dioxide and nitrate, electrons flow from ammonia nitrogen to oxygen, and nitrate is formed through autotrophic nitrification, which is then recycled back to reactor 1.

[0006] - Short-path nitrification anaerobic ammonium oxidation process. Figure 3A short-cut nitrification anaerobic ammonium oxidation (AMO) process is illustrated. In this process, half of the ammonia nitrogen is converted to nitrite during partial nitrification, and the remaining ammonia nitrogen and nitrite are then removed simultaneously by the AMO process. This process does not require organic matter, thus saving aeration energy. However, nitrite, as a key substrate for AMO, is readily consumed by nitrite-oxidizing bacteria (NOB) even with dissolved oxygen levels as low as 1–3 mg / L, making its application difficult (Cao et al., 2017). Although short-cut AMO technology has been developed on a laboratory scale, a pH below 4.5–5.0 is required to inhibit nitrite-oxidizing bacteria, which is unsuitable for AMO (Wang et al., 2021).

[0007] Denitrification anaerobic ammonium oxidation process. Figure 4 The reaction mechanism of process A, denitrification anammox, and the flow chart of process B, denitrification anammox, are shown. In this process, half of the ammonia nitrogen in the wastewater is oxidized to nitrate, and then reduced to nitrite. The resulting nitrite, along with the remaining ammonia nitrogen, is removed through anammox. Figure 4 As shown in B, the denitrification anaerobic ammonium oxidation process includes anaerobic treatment (1), nitrification treatment (2), and denitrification treatment (3). This invention is based on the following findings: in the nitrification reactor, ammonia nitrogen is mainly oxidized to nitrate, while under denitrification conditions, nitrite can be generated from nitrate, thus resulting in anaerobic ammonium oxidation. The generation of nitrite in the denitrification reactor is best controlled and stimulated by a characteristic feed pattern based on a discontinuous substrate gradient. However, there are several problems: (1) organic matter, one of the main electron donors, may lead to the overgrowth of heterotrophic bacteria, thereby harming mass conversion and anaerobic ammonium oxidation activity (Du et al., 2016); (2) the efficiency of the entire system is low, only 0.08 g N / (Ld) (Kalyuzhnyi et al., 2006); (3) the contribution of anaerobic ammonium oxidation to denitrification is unclear; (4) no enrichment and retention of anaerobic ammonium oxidizing bacteria has been demonstrated when treating mainstream wastewater with high flow rates and low concentrations of COD and nitrogen.

[0008] Sulfur (thiosulfate or sulfide) driven denitrification anaerobic ammonia oxidation (SDA) process. Figure 5A sulfur-driven denitrifying anaerobic ammonium oxidation (SDA) process is illustrated (based on the dosage of sulfide or thiosulfate). Both processes target wastewater containing both ammonia nitrogen and nitrate. Sulfur compounds are used as electron donors for partial denitrification, providing nitrite for the anaerobic ammonium oxidation reaction. Sulfur-driven denitrifying anaerobic ammonium oxidation (SDA) achieves a nitrogen removal rate as high as 0.29 g N / (Ld) (Deng et al., 2019, 2021). Furthermore, sulfur-oxidizing bacteria (SOB) can work well in synergy with anaerobic bacteria (AnAOB) (Deng et al., 2022). However, this may not be practical for treating wastewater containing only ammonia nitrogen. More importantly, in previous reports, SDA was achieved through external addition of sulfur compounds, making its application in mainstream wastewater treatment uneconomical. Summary of the Invention

[0009] The cost of removing organic matter and nitrogen from biological wastewater is high aeration energy consumption, which accounts for 45-70% of the total energy consumption of wastewater treatment plants. Anaerobic ammonium oxidation (ANAMO) requires only lower aeration energy and does not require organic matter for nitrogen removal. When combined with organic matter collection processes, it can reduce aeration energy consumption by more than 60% and recover 90% of the organic matter (energy). However, after more than a decade of effort, the effectiveness of ANAMO in mainstream wastewater treatment remains difficult to prove.

[0010] To address the aforementioned problems, this invention provides an economical and effective integrated water treatment process coupled with anaerobic ammonia oxidation. This invention also provides an economical and effective method for generating reducing sulfur products, effectively providing sulfides and thiosulfates. Furthermore, this invention validates the feasibility of anaerobic ammonia oxidation in this process through long-term operational results, material transformation pathways, and effective microbial enrichment.

[0011] Specifically, this invention provides:

[0012] 1. A wastewater treatment method, comprising:

[0013] The sulfide and thiosulfate generation step utilizes sulfur from wastewater to produce sulfur.

[0014] compounds and thiosulfates

[0015] The denitrification anaerobic ammonium oxidation step utilizes sulfides and thiosulfates to drive the denitrification of nitrates to nitrites, and then removes nitrogen (i.e., simultaneous removal of ammonia and nitrite) through anaerobic ammonium oxidation.

[0016] The nitrate supply step supplies nitrate to the denitrification anaerobic ammonium oxidation step.

[0017] The wastewater generated from the nitrate supply step and / or the denitrification anaerobic ammonium oxidation step is used as effluent.

[0018] Optionally, the method includes operating at least a first reactor and a second reactor.

[0019] The first reactor is an anaerobic organic matter removal reactor, and the first reactor is configured to (a) induce a sulfur cycle through organic matter oxidation and sulfate reduction to produce a treated liquid containing sulfides and thiosulfates, and (b) transfer the treated liquid to the second reactor.

[0020] The second reactor is a biological denitrification reactor, and the second reactor is configured to (c) receive wastewater containing nitrates; (d) denitrify the nitrates to nitrites, and then denitrify them together with ammonium in the wastewater through anaerobic ammonia oxidation; and (e) discharge the treated wastewater.

[0021] Optionally, the method further includes operating a third reactor, which is a nitrification reactor, wherein the third reactor is configured to: (f) receive treated wastewater from the second reactor; (g) oxidize ammonium in the wastewater to nitrite / nitrate to produce nitrated wastewater; (h) recycle the nitrated wastewater back to the second reactor; and (i) the treated liquid is the final effluent.

[0022] Optionally, the feed to the first, second, and third reactors is based on a continuous flow mode.

[0023] Optionally, ammonia, sulfates, and organic matter may originate from wastewater.

[0024] Optionally, the COD / ammonia (gCOD / gN) ratio in the wastewater is greater than 0.6, and the sulfate / ammonia (gS / gN) ratio is greater than 0.3.

[0025] Optionally, the organic matter is oxidized to carbon dioxide in the anaerobic organic matter removal reactor with an efficiency of 50-80%.

[0026] Optionally, sulfates are reduced to sulfides and thiosulfates in an anaerobic organic matter removal reactor.

[0027] Optionally, the method removes 60-90% of the nitrogen through anaerobic ammonia oxidation.

[0028] Optionally, in the third reactor, 80% or more of the ammonium in the wastewater is oxidized to nitrate / nitrite.

[0029] Optionally, the recycling ratio of the nitrified wastewater is 1.5-2.0.

[0030] Optionally, the first reactor, the second reactor, and the third reactor are selected from at least one of a mobile biofilm bioreactor, a granular sludge bed reactor, an attached growth reactor, and a membrane bioreactor.

[0031] 2. A wastewater treatment system, comprising:

[0032] The first reactor is configured to receive wastewater containing sulfur components and ammonia nitrogen, and to utilize the sulfur components in the wastewater to produce sulfides and thiosulfates.

[0033] The second reactor is configured to receive wastewater containing nitrates; denitrify the nitrates to nitrites, then denitrify them together with ammonia nitrogen in the wastewater through anaerobic ammonia oxidation; and output the treated wastewater.

[0034] A nitrate supply unit is configured to supply wastewater containing nitrates to the second reactor.

[0035] Optionally, the wastewater treatment system further includes a third reactor, which is a nitrification reactor, and is configured to: receive the treated wastewater from the second reactor, oxidize the ammonia nitrogen in the wastewater to nitrite / nitrate to produce nitrified wastewater; recycle the nitrified wastewater back to the second reactor; and output the treated liquid as final effluent.

[0036] Optionally, the first reactor includes at least a first vessel for providing mixing and stirring;

[0037] The second reactor receives effluent from the first container and provides anaerobic stirring and performs partial denitrification and anaerobic ammonium oxidation reactions.

[0038] The third reactor receives effluent from the second reactor and performs nitrification; the effluent from one end of the third reactor is then returned to the second reactor.

[0039] The third reactor drains water at the other end, and this drainage is the final effluent of the system.

[0040] Optionally, the anaerobic stirring is magnetic stirring.

[0041] Preferably, the first and second reactors further include biological packing material as a biofilm carrier.

[0042] Preferably, the wastewater treatment system further includes an air pump for aerating the third reactor and an airflow meter between the air pump and the third reactor.

[0043] The first, second, and third reactors are optionally selected from at least one of biofilm reactors, granular sludge bed reactors, attached growth reactors, and membrane bioreactors.

[0044] The beneficial effects of this invention are:

[0045] 1. Compared with existing conventional activated sludge processes, this process can reduce aeration energy consumption by about 60% and reduce reliance on external carbon sources by effectively coupling anaerobic ammonium oxidation, saving more than 65% of carbon sources in the nitrogen removal process.

[0046] 2. Compared with the short-cut nitrification anaerobic ammonium oxidation process, this process does not require real-time and precise control of reaction operating conditions, and it is stable in long-term operation. Anaerobic ammonium oxidation can effectively enrich and exert its effects, so it is more promising to be applied to mainstream wastewater treatment.

[0047] 3. Compared to denitrification ammonia oxidation processes, which have strict requirements on the C / N ratio, anaerobic ammonia oxidation bacteria risk being displaced from the microbial community and leading to long-term operational instability if the C / N ratio exceeds 2.7 during water quality fluctuations. However, even with a C / N ratio between 2.7 and 4.0, the anaerobic ammonia oxidation bacteria in the process of this invention can be effectively enriched.

[0048] 4. Compared to sulfur-driven denitrification anaerobic ammonium oxidation process, this process does not require an external sulfur source and is more economical. Attached Figure Description

[0049] Figure 1 A conceptual SANIA process according to one embodiment of the present invention is shown.

[0050] Figure 2 The conventional sludge activation process is shown.

[0051] Figure 3 The short-path nitrification anaerobic ammonium oxidation process is shown.

[0052] Figure 4 The reaction mechanism of process A: denitrification ammonia oxidation and the flow chart of process B: denitrification ammonia oxidation are shown.

[0053] Figure 5 A sulfur-driven denitrification anaerobic ammonia oxidation process is shown (based on the amount of sulfide or thiosulfate used).

[0054] Figure 6 The conceptual SANIA process according to the present invention is illustrated.

[0055] Figure 7 The construction of a laboratory-scale system according to one embodiment of the present invention is shown.

[0056] Figure 8The construction of a SANIA system according to another embodiment of the present invention is shown. Detailed Implementation

[0057] In one embodiment, the present invention provides a wastewater treatment method, comprising: a sulfide and thiosulfate generation step, wherein the step utilizes sulfur from the wastewater to generate sulfides and thiosulfates; a denitrification anaerobic ammonium oxidation step, wherein the step utilizes sulfides and thiosulfates to drive the denitrification of nitrates to nitrites and removes nitrogen through anaerobic ammonium oxidation; and a nitrate supply step, wherein the nitrate is supplied to the denitrification anaerobic ammonium oxidation step. The nitrate supply step generates treated wastewater as effluent.

[0058] Preferably, the method includes operating at least a first reactor and a second reactor.

[0059] The first reactor is an anaerobic organic matter removal reactor, and the first reactor is configured to (a) induce a sulfur cycle through organic matter oxidation and sulfate reduction to produce a treated liquid containing sulfides and thiosulfates, and (b) transfer the treated liquid to the second reactor.

[0060] The second reactor is a biological denitrification reactor, and the second reactor is configured to (c) receive wastewater containing nitrates; (d) denitrify the nitrates to nitrites, and then denitrify them together with ammonia nitrogen in the wastewater through anaerobic ammonia oxidation; and (e) discharge the treated wastewater.

[0061] The wastewater treatment method of the present invention further includes operating a third reactor, which is a nitrification reactor, wherein the third reactor is configured to: (f) receive the treated wastewater from the second reactor; (g) oxidize the ammonia nitrogen in the wastewater to nitrite / nitrate to produce nitrified wastewater; (h) recycle the nitrified wastewater back to the second reactor; and (i) the treated liquid is the final effluent. Preferably, the recycling ratio of the nitrified wastewater is 1.5-2.0. In this document, the recycling ratio refers to the volume ratio of the nitrified wastewater recycled to the second reactor relative to the effluent from the third reactor. This recycling ratio is crucial for the process; in steady-state operation, the recycling ratio determines whether the effluent after nitrification treatment can provide sufficient nitrate to the second reactor to ensure adequate nitrogen removal, and also determines the upper limit of the effluent quality.

[0062] Preferably, the feed to the first reactor, the second reactor, and the third reactor is based on a continuous flow mode.

[0063] Preferably, the ammonia, sulfates, and organic matter are derived from wastewater.

[0064] Preferably, the COD / ammonia (gCOD / gN) ratio in the wastewater is higher than 0.6, and the sulfate / ammonia (gS / gN) ratio is higher than 0.3.

[0065] Preferably, the efficiency of oxidizing organic matter into carbon dioxide in the anaerobic organic matter removal reactor is 50-80%.

[0066] Preferably, sulfate is reduced to sulfides and thiosulfates in the anaerobic organic matter removal reactor.

[0067] In one embodiment, the wastewater treatment method of the present invention achieves a nitrogen removal rate of 60-90% through anaerobic ammonia oxidation.

[0068] Preferably, in the third reactor, 80% or more of the ammonia nitrogen in the wastewater is oxidized to nitrate / nitrite.

[0069] This invention proposes an innovative and compact integrated process of sulfate reduction, autotrophic denitrification, nitrification and anaerobic ammonia oxidation (SANIA) for sustainable biological wastewater treatment. Figure 1 A conceptual SANIA process according to one embodiment of the present invention is illustrated. For example... Figure 1 As shown, this process involves carbon cycling, sulfur cycling, and single cycling, and can include biological processes such as sulfate reduction, autotrophic denitrification, ammonia oxidation, and nitrification. In the SANIA process, electrons in organic matter are first transferred to sulfides and thiosulfates by sulfate-reducing bacteria, and then used for autotrophic denitrification (including NO3). - →NO2 - and NO2 - →N2), where nitrite can be effectively accumulated through the synergistic action of sulfur-oxidizing bacteria and denitrifying bacteria, and used for denitrification reaction (NH4). + +NO2 - →N2), electrons are transferred from ammonia nitrogen to nitrogen gas. Nitrates are provided by nitrification under the action of nitrifying bacteria, where electrons in ammonia nitrogen (ammonium) are transferred to oxygen. This invention can incredibly save at least 80% of organic matter consumption and over 60% of aeration energy consumption. By combining it with widely used energy-saving organic matter (energy) recovery processes, the energy recovery of organic matter (energy) can be maximized and the energy input of organic matter and denitrification can be minimized, thereby achieving energy neutralization in wastewater treatment.

[0070] Since the sulfate concentration in wastewater is typically 20-180 mg S / L (Pikaar et al., 2014; Van denBrand et al., 2015; Wu et al., 2016), one embodiment of the present invention provides a sulfate reduction, autotrophic denitrification, nitrification, and anaerobic ammonia oxidation (SANIA) process. Figure 6As shown, this process utilizes sulfate reduction to produce sulfides and thiosulfates, thereby eliminating the external supply of sulfur compounds. The sulfide and thiosulfate co-driven PD / A (MSPDA) process facilitates stable and rapid denitrification with a low risk of consumption by anaerobic ammonia-oxidizing bacteria. Furthermore, nitrates produced by anaerobic ammonia oxidation can be effectively removed by PDA. Finally, in this process, nitrates can be stably supplied through nitrification.

[0071] In a preferred embodiment, the SANIA process comprises three reactors: the first reactor is driven by sulfate-reducing bacteria for sulfate reduction, the second reactor is driven by SOB and AnAOB for MSPDA, and the third reactor is driven by ammonia-oxidizing bacteria for nitrification. Figure 6 (As shown). The main reactions are summarized below:

[0072]

[0073]

[0074]

[0075]

[0076] This invention is based on two findings: (1) the efficient generation of sulfides and thiosulfates during sulfate reduction, used to treat wastewater with sulfate content higher than 30 mg S / L; and (2) the achievement of a high anaerobic ammonia oxidation rate of 0.7 g N / (Ld) in MSPDA. The rapid anaerobic ammonia oxidation and denitrification enable this invention to be applied to mainstream wastewater treatment. The sulfur cycle-based biological wastewater treatment inherits from SANI... @ The advantages of this process include minimal sludge production and a significant reduction in sulfate demand. Most importantly, in this invention, anaerobic ammonium oxidation primarily handles denitrification, thereby reducing organic matter demand by up to 64% and denitrification aeration energy by 39%.

[0077] like Figure 6 As shown, our laboratory has established an integrated system comprising three mobile biofilm bioreactors (MBBRs). An overview of the relevant biological processes is as follows:

[0078] In the first reactor—the anaerobic organic matter removal reactor:

[0079] (a) In the first reactor, the sulfur cycle is induced by the oxidation of organic matter and the reduction of sulfate, with sulfides and thiosulfates being the products of sulfate reduction;

[0080] (b) Transfer the treated liquid to a second bioreactor.

[0081] In the second reactor – the biological denitrification reactor:

[0082] (c) Nitrified wastewater containing nitrite / nitrate is recycled back to this reactor from the third reactor;

[0083] (d) Nitrate is denitrified to nitrite, and then nitrite is removed simultaneously with ammonia nitrogen (e.g., ammonium cations) by anaerobic ammonia oxidation;

[0084] (e) The treated liquid is then transported to a third bioreactor.

[0085] In the third reactor – the bioammonia oxidation reactor:

[0086] (f) Ammonia nitrogen is oxidized to nitrite and nitrate;

[0087] (g) The treated liquid is the final effluent.

[0088] Depending on the reactor design, other types of reactor designs besides MBBR, such as granular sludge beds, attached growth reactors, and membrane bioreactors, can also be used to implement this invention.

[0089] Use other sulfur components

[0090] In the SANIA process, in addition to sulfates, other possible sulfur sources can be utilized to generate or supply sulfides and thiosulfates, such as sulfites, thiosulfates, and sulfur from industrial waste or wastewater. 0 (Ahmad et al., 2015; Jiang et al., 2013).

[0091] Example 1

[0092] System setup. A 320-day laboratory-scale study was conducted using synthetic mainstream wastewater after organic matter capture. The installed laboratory-scale system ( Figure 7 The system comprises two mobile biofilm bioreactors (MBBRs): a sulfate reduction bioreactor 1 (SR-MBBR) and a short-cut denitrification anaerobic ammonium oxidation reactor 2 (MSPDA-MBBR). Wastewater containing organic matter, sulfate, and ammonium is fed into the SR-MBBR. The wastewater also contains nitrate (simulating nitrification wastewater) (NO3). - A nitrogen content of 35±4 mgN / L was fed into the MSPDA-MBBR for denitrification. Both reactors had an inner diameter of 120 mm and a height of 120 mm, a working volume of 1 L, and a headspace of 0.35 L. 300 Mutag BioChip30 units were used in the SR-MBBR. TM The carrier has a fill rate of 40% and an effective surface area of ​​2.2 m². 256 K3 AnoxKaldnes were used in the hypoxic MSPDA-MBBR. TM The carrier has a fill rate of 50% and an effective surface area of ​​0.25 m². 2 Both reactors were mixed at a rate of 130-200 rpm. Operating conditions for both reactors, including pH, ORP, dissolved oxygen, temperature, and HRT, are shown in Table 1.

[0093] Inoculation. The vectors in SR-MBBR and MSPDA-MBBR were derived from two parent reactors that had been running in our laboratory for two years (Leung et al., 2019).

[0094] Synthetic wastewater. For example... Figure 7 As shown, the influent is the synthetic wastewater, and the synthetic wastewater contains sulfate (SO4). 2- Chemical oxygen demand (COD) and ammonia concentration (NH4+) + The concentrations of nitrogen (NO) were 54±10 mgS / L, 111±14 mg / L, and 27±4 mgN / L, respectively. During operation, the dissolved oxygen (DO) in the influent ranged from 0.5 to 3.6 mg / L. Specifically, glucose and sodium acetate trihydrate (carbon ratio 1:1) were used as organic sources. The wastewater also contains 270 mg / L sodium bicarbonate as an alkaline source, 10 mg / L yeast, 11.3 mg / L KH₂PO₄, 67 mg / L MgCl₂-2H₂O, 75 mg / L CaCl₂-2H₂O, and 1 mL / L trace element solution (0.5 g / L EDTA, 0.1 g / L FeSO₄, 8 g / L ZnSO₄-7H₂O, 4 g / L CoCl₆H₂O, 20 g / L MnCl₂-4H₂O, 5 g / L CuSO₄-5H₂O, 4 g / L NaMoO₄-2H₂O, 4 g / L NiCl₂-6H₂O, 4 g / L NaSeO₄-10H₂O, and 0.2 g / L H₃BO₄). The simulated nitrification wastewater contains only nitrate, with an initial concentration of 650-700 mgN / L. After mixing with the effluent from the first reactor, the final average concentration of the influent to the second reactor is 35 ± 4 mg N / L. The flow rates of the synthetic wastewater and the simulated nitrification wastewater are 25 mL / min and 1.3 mL / min, respectively.

[0095] Table 1 Operating conditions of the laboratory-scale system

[0096]

[0097] performance

[0098] In the SR-MBBR, electrons from organic matter are effectively transferred to sulfate, producing sulfides and thiosulfates. Detailed concentrations in the influent and effluent are shown in Table 2. Performance stabilized around day 240, and from day 241 to 319 thereafter, COD removal rate, sulfide formation rate, and thiosulfate formation rate reached 0.9 g S / (m³). 2 -d), 0.3g S / (m 2 -d) and 0.1gS / (m 2 -d). Meanwhile, in the MSPDA-MBBR, the removal rates of sulfides, thiosulfates, ammonium, and nitrates reached 2.3 g S / (m²) on days 241–319. 2 -d), 0.9g S / (m 2 -d), 2.9g S / (m 2 -d) and 1.4g S / (m 2 -d).

[0099] The system exhibits the following characteristics: (1) high nitrogen removal rate (0.88 g N / (Ld), of which 81% is achieved through anaerobic ammonia oxidation); (2) 64% of organic matter can be saved for energy recovery, and aeration energy consumption is reduced by 64% and 39% in organic matter removal and nitrogen removal, respectively; (3) the start-up time of MSPDA-MBBR is only 135 days without the addition of nitrite and anaerobic ammonia oxidation sludge inoculation; (4) sludge production is 0.22 g VSS / g COD, which is much lower than 0.4-0.6 g VSS / g COD (Ekama et al, 2020).

[0100] The sulfur balance in the MSPDA was only 71%, indicating that sulfides and thiosulfates were not fully utilized. If the oxidation of sulfides and thiosulfates were fully realized, the performance of the MSPDA could be further improved. Meanwhile, the residual ammonium and nitrite concentrations in the effluent suggest that the anaerobic reaction could be further improved to enhance denitrification performance.

[0101] Table 2 Performance of SR-MBBR and MSPDA-MBBR during 241–319 days

[0102]

[0103] Example 2

[0104] System settings.

[0105] like Figure 8As shown, a system with three bioreactors (SR-MBBR, MSPDA-MBBR, and N-MBBR) was established and operated for over 130 days. The SR-MBBR receives influent and is heated in a water bath while being stirred by an agitator. The MSPDA-MBBR is stirred by a magnetic stirrer, with the treated liquid being transferred to the N-MBBR. The N-MBBR is also heated in a water bath and aerated by an external aeration device, thereby supplying oxygen. The aeration device includes an air pump for supplying air (containing oxygen) and a flow meter for controlling the air flow rate. The N-MBBR is a biological ammonia oxidation reactor, in which ammonia nitrogen is oxidized to nitrite and nitrate, and the treated liquid is the final effluent. Additionally, a portion of the nitrite / nitrate-containing wastewater is circulated back to the MSPDA-MBBR via a peristaltic pump. In this system, the carriers in the SR-MBBR and MSPDA-MBBR were obtained from Example 1. The MSPDA-MBBR was transferred to a 1.6L reactor and supplemented with 30 K3 carriers, thus extending the HRT to 1.1 h. In this system, simulated nitrification wastewater was replaced by nitrified MBBR (N-MBBR) to supply nitrates at a recycle ratio of 2.0. ActiveCell 920 carriers with an effective surface area of ​​1.22 m² were used in the N-MBBR. 2 Aeration was achieved by purging at a flow rate of 2 L / min. The nominal HRTs of SR-MBR, MSPDA-MBR, and N-MBR were 0.7 h, 1.1 h, and 3 h, respectively; therefore, the total HRT of SANIA was 4.7 h. No sludge was intentionally wasted in the system. The synthesized wastewater was consistent with that in Example 1.

[0106] Vaccination.

[0107] The carriers used in SR-MBBR and MSPDA-MBBR were taken from Example 1. The ActiveCell 920 carrier in N-MBBR was taken from a laboratory-scale nitrifying MBBR that had been running for more than 200 days with an influent ammonia nitrogen level of 100 mg N / L and an effluent ammonia nitrogen level of less than 10 mg N / L.

[0108] Table performance.

[0109] In SANIA, ammonium and nitrate were effectively removed, with total inorganic nitrogen (TIN, including ammonium, nitrite, and nitrate) decreasing from 33.0 ± 2.1 mg N / L to 13.9 ± 1.8 mg N / L. Specifically, nitrate was reduced in the MSPDA-MBBR, with only 1.3 ± 0.9 mg N / L in the effluent, indicating a well-confirmed reduction in nitrate. In contrast, ammonia nitrogen in the effluent was 10.3 ± 1.3 mg N / L, and nitrite was 2.3 ± 0.9 mg N / L, suggesting that denitrification could be further improved through anaerobic ammonia oxidation. Based on the ammonia nitrogen removal performance of the MSPDA-MBBR, 74% of the TIN was removed by anaerobic ammonia oxidation. The anaerobic ammonia oxidation rate in the SANIA process was 0.4 g N / (Ld), which is within the typical range of 0.3–0.6 g N / (Ld) for mainstream wastewater treatment (Laureni et al., 2016).

[0110] The system demonstrates that: (1) it effectively removes TIN; (2) it achieves an actual denitrification rate of 0.54 g N / (Ld); (3) it saves 64% of organic matter for energy recovery; (4) the total aeration energy consumption for organic matter and nitrogen removal is reduced by 55%; (5) the system has a short HRT of only 4.7 hours; and (6) the sludge production is 0.19 g VSS / g COD, which is much lower than 0.4-0.6 g VSS / g COD (Ekama et al., 2020).

[0111] Table 3 shows the system's performance stability during days 60-130.

[0112]

[0113] Compared to Example 1, the improvement of Example 2 lies in that it fully verifies the feasibility of the process. In Example 1, the simulated nitrification unit had low dissolved oxygen and sufficient nitrate supply in the effluent, which is more different from the actual situation. In Example 2, the nitrification unit is coupled into the system, which further verifies the feasibility of the process of the present invention.

[0114] It is understood that, within the spirit and scope of the invention as defined by the appended claims, those skilled in the art may make many other changes to the details, materials, steps, and arrangements described herein for explaining the characteristics of the subject matter. It should also be understood that the embodiments set forth herein are for illustrative purposes and are not intended to limit the scope of the subject matter, which is defined by the appended claims.

Claims

1. A method of treating wastewater, characterized by include: The step involves the generation of sulfides and thiosulfates, which utilizes sulfur components in wastewater to produce sulfides and thiosulfates. The denitrification anaerobic ammonium oxidation step utilizes sulfides and thiosulfates to drive the denitrification of nitrates to nitrites, and then removes nitrogen through anaerobic ammonium oxidation. The nitrate supply step supplies nitrate to the denitrification anaerobic ammonium oxidation step. The wastewater generated from the nitrate supply step and / or the denitrification anaerobic ammonium oxidation step is used as effluent.

2. The method according to claim 1, characterized in that... The method includes operating at least a first reactor and a second reactor. The first reactor is an anaerobic organic matter removal reactor, and the first reactor is configured to (a) induce a sulfur cycle through organic matter oxidation and sulfate reduction to produce a treated liquid containing sulfides and thiosulfates, and (b) transfer the treated liquid to the second reactor. The second reactor is a biological denitrification reactor, and the second reactor is configured to (c) receive wastewater containing nitrates; (d) denitrify the nitrates to nitrites, and then denitrify them together with ammonium in the wastewater through anaerobic ammonia oxidation; and (e) discharge the treated wastewater.

3. The method according to claim 2, characterized in that... The method further includes operating a third reactor, which is a nitrification reactor, wherein the third reactor is configured to: (f) receive treated wastewater from the second reactor; (g) oxidize ammonium in the wastewater to nitrite / nitrate to produce nitrated wastewater; (h) recycle the nitrated wastewater back to the second reactor; and (i) the treated liquid is the final effluent.

4. The method according to claim 3, characterized in that... The feed to the first, second, and third reactors is based on a continuous flow mode.

5. The method according to claim 2, wherein the ammonia, sulfate and organic matter are derived from wastewater.

6. The method according to any one of claims 1-5, wherein the COD / ammonia (gCOD / gN) ratio in the wastewater is higher than 0.6, and the sulfate / ammonia (gS / gN) ratio is higher than 0.

3.

7. The method according to any one of claims 2-5, wherein the efficiency of oxidizing organic matter into carbon dioxide in the anaerobic organic matter removal reactor is 50-80%.

8. The method according to any one of claims 1-5, wherein the sulfate is reduced to sulfide and thiosulfate in an anaerobic organic matter removal reactor.

9. The method according to any one of claims 1-5, wherein the nitrogen removal ratio by anaerobic ammonia oxidation is 60-90%.

10. The method of claim 3, wherein in the third reactor, 80% or more of the ammonium in the wastewater is oxidized to nitrate / nitrite.

11. The method according to any one of claims 3 or 10, wherein the recycling ratio of the nitrified wastewater is 1.5-2.

0.

12. The method according to any one of claims 3 or 10, wherein the first reactor, the second reactor, and the third reactor are selected from at least one of a mobile biofilm bioreactor, a granular sludge bed reactor, an attached growth reactor, and a membrane bioreactor.

13. A wastewater treatment system, characterized in that... include: The first reactor is configured to receive wastewater containing sulfur components and ammonia nitrogen, and to utilize the sulfur components in the wastewater to produce sulfides and thiosulfates. The second reactor is configured to receive wastewater containing nitrates and treated liquid containing sulfides and thiosulfates from the first reactor. Nitrate is denitrified to nitrite, and then denitrified together with ammonia nitrogen in wastewater through anaerobic ammonia oxidation. And the output of treated wastewater; as well as A nitrate supply unit is configured to supply wastewater containing nitrates to the second reactor.

14. The wastewater treatment system according to claim 13, characterized in that... It also includes a third reactor, which is a nitrification reactor, and is configured to receive the treated wastewater from the second reactor and oxidize the ammonia nitrogen in the wastewater to nitrite / nitrate to produce nitrified wastewater; The nitrified wastewater is recycled to the second reactor, and the treated liquid is output as the final effluent.

15. The wastewater treatment system according to claim 14, characterized in that... The first reactor includes at least a first vessel for providing mixing and stirring; The second reactor receives effluent from the first container and provides anaerobic stirring and performs partial denitrification and anaerobic ammonium oxidation reactions. The third reactor receives the effluent from the second reactor and performs nitrification. The effluent from one end of the third reactor is then discharged back into the second reactor. and The third reactor drains water at the other end, and this drainage is the final effluent of the system.

16. The wastewater treatment system according to claim 15, characterized in that... The anaerobic stirring is magnetic stirring.

17. The wastewater treatment system according to claim 16, wherein the first reactor and the second reactor further include biological packing material as a biofilm carrier.

18. The wastewater treatment system of claim 16, wherein the wastewater treatment system further comprises an air pump for aerating a third reactor and an airflow meter between the air pump and the third reactor.

19. The wastewater treatment system according to any one of claims 14 to 18, characterized in that... The first reactor, the second reactor, and the third reactor are selected from at least one of a biofilm reactor, a granular sludge bed reactor, an attached growth reactor, and a membrane bioreactor.

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