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a Configuration of the sequencing batch reactor and b organic loading rate over the operational period
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Aerobic granular sludge technology has great potential for the treatment of petroleum refinery wastewater. However, strategies to shorten the granulation time and improvement the stability still need to be developed. In this work, biochar was prepared from waste petroleum activated sludge (biochar-WPS) and used in a sequencing batch reactor for the...
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... SBR reactors (R0, control; Rw, added with biochar-WPS) were employed, with a working volume of 2 L (7.0 cm of internal diameter and 58.2 cm of height). Biochar-WPS was added into Rw with a concentration of 3% (v/v) ( Chen et al. 2018). Air was supplied with an air pump (YTZ-312, Shandong, China) through the diffusers located in the reactor bottom (Fig. 1a), and the dissolved oxygen (DO) concentration was kept at 6.5-8.5 mg/L. The influent and effluent were controlled by two peristaltic pumps (BT300-2J, Baoding, China), with a volumetric exchange ratio of 50%. The overall system was controlled by a time controller (KWD-T02, Zhejiang, ...
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... experimental period consisted of four phases: start-up and acclimation (days 1-42), load shocking (days 43-62), recovery (day 63-76) and improvement (days 77-120). The operational conditions are shown in Fig. 1b. In the first phase, the influent oil concentration increased from 127.07 to 298.93 mg/L while the settling time decreased from 30 min (days 1-9) to 5 min (days 10-15 day) and to 3 min (days 16-42). The reactors were operated with a cycle of 4.8 h for the first period. During the load shocking phase, a 4-h cycle was used instead of the ...
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... for OLR to 3.8 kg COD (m 3 days) −1 decreased the COD removal efficiency in R0 (64.08%), which required 3 days to recover (90.26%). COD removal efficiency was also reduced to a much lesser degree (86.52%) in the Rw reactor and rapidly recovered (94.91%) in 1 day. Increasing the OLR [4.50 kg COD (m 3 days) −1 ] and influent COD (1500 mg/L) (Fig. 1b) resulted in a decline in COD removal for both R0 (70.83%) and Rw (71.47%). During the recovery period, the OLR reduced to below 2.0 kg COD (m 3 days) −1 , and the settling time increased to 5 min. Both R0 and Rw recovered their COD removal efficiencies up to 90%. The effects on COD removal for both R0 (93.09%) and Rw (97.44%) were ...
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... concentration of EPS in the sludge was determined (Fig. S1). EPS content significantly increased during aerobic granulation and reached a maximum for Rw [61.66 mg/ (g·VSS)] on day 15, whereas the maximum concentration for R0 [51.12 mg/(g·VSS)] was observed on day 30. These results coincided with the observed granulation. It had been reported that EPS secretion occurs mostly aerobically and has ...
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... Moreover, many kinds of small particles, such as zeolite, activated carbon, biochar, etc. have been used to accelerate microbial aggregation, acting as micro-nuclei for microbial attachment, supporting biomass retention, and facilitating faster granule development (Fernández et al., 2008;Gu et al., 2020;Ming et al., 2020;Wang et al., 2020b). ...
... Biochar has been applied as adsorbent due to its high pollutant retention such as: heavy metals, organic pollutants (dye, antibiotics, pesticides) or inorganic pollutants, such as phosphate (P), NH 4 + , nitrate (NO 3 − ) (Gai et al., 2014;Zama et al., 2017;Zeng et al., 2018) and it is usually utilized for soil improvement . Besides, biochar is a biocompatible material as its high surface area and porosity favor microbial adhesion and aggregation, respectively (Ming et al., 2020;Wang et al., 2020b). Xie et al. (2022) reported a positive correlation between these characteristics of biochar and the protection of anammox bacteria from organic carbon stress. ...
... However, it has low surface area and porosity. Conversely, biochar produced at high temperatures results in the destruction of functional groups but it exhibits a high surface area and high porosity index, providing a habitat for microbial growth (Ming et al., 2020;Wang et al., 2020b;Xie et al., 2022). However, too low pyrolysis temperature may not create sufficient electron storage capacity in the biochar (Xin et al., 2021). ...
... This opens a new method to enhance treatment efficiency of aerobic granular sludge systems. For example, Wang et al., (2020) used biochar produced from waste petroleum-activated sludge to enhance granulation and degradation of COD in petroleum refinery wastewater by aerobic granular sludge successfully [12]. As carrier media to be used for wastewater treatment by aerobic granular sludge, sludge biochar may exert both positive and negative effects on aerobic granules. ...
Sludge biochar can be used as bio-carrier to enhance aerobic granular sludge, however, its impact on the formation and especially long-term stability of aerobic granules has not been fully investigated. In this paper, aerobic granular sludge was cultivated in two parallel sequencing batch reactors (SBRs), R1 and R2, with and without sludge biochar addition in the activated sludge inoculum, respectively. The sludge characteristics, wastewater treatment performance, and microbial community structure of granular sludge were examined on a 240-day operation, during which aerobic granular sludge in the two reactors experienced dynamic changes including granule formation, maturation, breakage, filamentous proliferation, and recovery. Aerobic granules in R1 with biochar formed two weeks earlier than that in R2, presenting a larger mean size, and higher settling ability and biomass retention in the granule maturation period. Concurrently, aerobic granules in R1 showed higher denitrification ability with over 80% removal efficiency throughout the whole operation period. During the maturation period, the ratio of food to biomass (F/M) in R1 was below 0.5 gCOD/gVSS d while it ranged between 0.5 and 1.0 gCOD/gVSS d in R2 due to lower biomass retention. The elemental analysis showed more Ca and P accumulation in aerobic granular sludge from R1, with 3% Ca and 2.75% P in sludge from R1 and 0.91% Ca and 0.75% P in sludge from R2, respectively. The microbial community in R1 had higher richness, diversity, excretion of extracellular polymer substances (EPSs) and abundance of denitrifying genera than that in R2, supporting its higher stability and denitrification performance. These results demonstrated that aerobic granular sludge formed by using sludge biochar as a carrier for granulation can speed up granule formation, improve denitrification performance, and enhance the long-term stability of aerobic granules. The findings disclosed the enhancing effects of biochar for wastewater treatment by aerobic granular sludge, suggesting the potential of practical application of biochar in aerobic granular sludge-based reactors.
... Within the produced granules, enhanced microbial abundance and variety were detected, as well as a higher percentage of denitrifying bacteria (4%). These findings suggest that employing biochar-WPS for rapid granulation in SBR is a viable alternative that can provide an efficient, environmentally friendly, and cost-effective approach for the treatment of petroleum refinery wastewater ( Wang et al., 2020 ). ...
... The produced granules showed greater microbial variety and richness, and a higher (4%) proportion of denitrifying bacteria. ( Wang et al., 2020 ) Petroleum refinery activated sludge Real refinery wastewater Treatment by biological process ...
The petroleum industry activities unavoidably generate a large quantity of sludge named Petroleum industry sludge (PIS). The generation rate has been increasing because of the ascending energy demand. It is a potential energy resource. PIS has been shown to contain hazardous constituents that may have negative consequences on the environment and public health. Thus, the treatment and disposal of this waste is a global issue. Numerous treatment methods have been demonstrated to reduce sludge volume and toxicity and recover petroleum components. The sludge qualities affect how effective they are. These treatment strategies can reduce the toxic substances in sludge and reduce their detrimental effects on human health and the environment. However, because of the sludge's tenacious character, only a few technologies can meet strict environmental laws while using a sizable amount of water, electricity, and chemicals. PIS treatment methods that are both waste-free and cost-effective are currently unavailable. In terms of environmental engineering significance, this study adopted the systematic review to discuss the waste to resource potential applications of PIS for reusability in sustainable construction, wastewater treatment applications, and gas generation. PIS application ineffective microorganism biofertilizer production, levan production, rubber tires manufacturing, metal catalysts synthesis, carbon–clay composites for use in sensors and electronic devices were also discussed. That is not enough, this review also found that the adoption of the circular economy that represents a new direction to create value and prosperity by elongating product lifespan and moving the waste from the end of the supply chain to the outset is very important. Thus, the circular economy potential of PIS to achieve self-cycle operation through the concept of “wastes-treat-wastes” in the petroleum industry was extensively discussed.
... Maintaining stable and efficient sludge granulation is one of the main challenges for the broad adoption of aerobic granular sludge. This could be addressed by the well-developed porous structure and high hydrophilicity of engineered biochar, which can aid sludge aggregation, microbial colonization and adhesion 56 . Applying biochar as a nucleating carrier can promote sludge granulation for a successful aerobic granular sludge start-up process 57 . ...
Biochar, a carbon-rich material made from the partial combustion of biomass wastes, is an emerging material of interest as it can remediate pollutants and serve as a negative carbon emission technology. In this Review, we discuss the application of biochar in municipal wastewater treatment, industrial wastewater decontamination and stormwater management in the context of sustainable development. By customizing the biomass feedstock type and pyrolysis conditions, biochar can be engineered to have distinct surface physicochemical properties to make it more efficient at targeting priority contaminants in industrial wastewater treatment via adsorption, precipitation, surface redox reactions and catalytic degradation processes. Biochar enhances flocculation, dewatering, adsorption and oxidation processes during municipal wastewater treatment, which in turn aids sludge management, odour mitigation and nutrient recovery. The addition of biochar to sustainable drainage systems decreases potential stormwater impact by improving the structure, erosion resistance, water retention capacity and hydraulic conductivity of soils as well as removing pollutants. The feasibility of scaling up engineered biochar production with versatile, application-oriented functionalities must be investigated in collaboration with multidisciplinary stakeholders to maximize the environmental, societal and economic benefits.
... The reduction of turbidity, SS, hydrocarbons, COD, and BOD5 reached 91%, 87%, 97%, 85%, and 92%, respectively. Wang et al. [6] prepared biochar from activated sludge of residual petroleum and used it in a batch reactor for the treatment of liquid effluent from the petroleum refinery. Synthesized biochar exhibited interesting properties. ...
Hydrocarbons, aldehydes, sulfides, heavy metals, and other contaminants from petroleum treatment processes have been discovered in the oil and gas industry liquid discharge. Hydrocarbons primarily cause the pollution shared by all units. The purpose of this study is to assess the performance of the coagulation-flocculation process in the primary treatment stage for the removal of hydrocarbons and turbidity from the effluent of the Algerian oil refinery RA1/Z. Using 1 g/L of calcium hydroxide coagulant and operating at a stirring speed of 100 rpm for 3 minutes, an excellent elimination of 95.1 % and 90.4 %, respectively, of turbidity and hydrocarbons, was achieved.
... The reduction of turbidity, SS, hydrocarbons, COD, and BOD5 reached 91%, 87%, 97%, 85%, and 92%, respectively. Wang et al. [6] prepared biochar from activated sludge of residual petroleum and used it in a batch reactor for the treatment of liquid effluent from the petroleum refinery. Synthesized biochar exhibited interesting properties. ...
Hydrocarbons, aldehydes, sulfides, heavy metals, and other contaminants from petroleum treatment processes have been discovered in the oil and gas industry liquid discharge. Hydrocarbons primarily cause the pollution shared by all units. The purpose of this study is to assess the performance of the coagulation-flocculation process in the primary treatment stage for the removal of hydrocarbons and turbidity from the effluent of the Algerian oil refinery RA1/Z. Using 1 g/L of calcium hydroxide coagulant and operating at a stirring speed of 100 rpm for 3 minutes, an excellent elimination of 95.1 % and 90.4 %, respectively, of turbidity and hydrocarbons, was achieved.
... The reduction of turbidity, SS, hydrocarbons, COD, and BOD5 reached 91%, 87%, 97%, 85%, and 92%, respectively. Wang et al. [6] prepared biochar from activated sludge of residual petroleum and used it in a batch reactor for the treatment of liquid effluent from the petroleum refinery. Synthesized biochar exhibited interesting properties. ...
Hydrocarbons, aldehydes, sulfides, heavy metals, and other contaminants from petroleum treatment processes have been discovered in the oil and gas industry liquid discharge. Hydrocarbons primarily cause the pollution shared by all units. The purpose of this study is to assess the performance of the coagulation-flocculation process in the primary treatment stage for the removal of hydrocarbons and turbidity from the effluent of the Algerian oil refinery RA1/Z. Using 1 g/L of calcium hydroxide coagulant and operating at a stirring speed of 100 rpm for 3 minutes, an excellent elimination of 95.1 % and 90.4 %, respectively, of turbidity and hydrocarbons, was achieved.
... Underneath the assumption that the elimination was mostly due to aerobic dilapidation, universal parameters such as chemical oxygen demand, biochemical oxygen demand and ammonia-nitrogen were employed as a substrate for study. The first order substrate removal model, as well as the modified Stover and Kincannon and Monod models, are wellknown kinetics models used to estimate reactor performance and design [25,26]. ...
The wastewater generated from the petroleum industry is incredibly recalcitrant and requires a lot of energy to clean. As a result, managing the treatment of petroleum industry wastewater (PIWW) in underdeveloped nations is problematic. Co-treatment with domestic wastewater (DWW) is a viable solution to the problem. The study was conducted for co-treatment of PIWW with DWW, in a lab scale extended aeration (EAS) reactor. The outcome identifies that the maximum ammonia removal was achieved at 20% PIWW, which was 88.3%. Among the studied kinetic model of nutrient removal, modified Stover-Kincannon model and Monod model was found fit with experimental data with the coefficient of correlation (R2) greater than 0.99 and 0.98 respectively, evidently postulate that these models can be used to predict the reactor’s effectiveness for nutrient removal. Thus, EAS treatment plant can be build for the treatment of PIWW together with DWW.
Keywords—extended aeration activated sludge (EAS) reactor, petroleum industry wastewater (PIWW), domestic wastewater (DWW), nutrient removal, first-order substrate removal model; Stover–Kincannon model; Monod model.
... Inert carrier particles generally have a porous structure, large specific surface area and good adsorption performance. By adding powdered zeolite [12], granular activated carbon (GAC) [13] and biochar [14] as carriers in SBR, the sludge could be granulated faster than treatment without carrier, with granulating time of 8, 20 and 15 days, respectively, while no obvious particle is observed in the control group without carrier addition. ...
... Studies suggest that granulation was completed within 15 days after the addition of biochar, compared to 30 days for reactors without a carrier. Moreover, in reactors with and without biochar, particles larger than 460 μm accounted for 79.6% and 53.8%, respectively [14]. ...
Recently, hydrocyclone separator is introduced into the field of aerobic granular sludge (AGS), and applied in wastewater treatment plant to recover the dense sludge. However, the function of hydrocyclone separator for AGS cultivation is still unclear. Thus, the granulating and granular separation efficiencies of hydrocyclone separator were investigated from perspectives of experiment and hydrodynamic modelling. By comparing traditional sequencing batch reactor, the introduction of hydrocyclone separator greatly decreased the mixed liquid suspended sludge by maximum 61%, although it could improve the sludge settling performance and reduce SVI, no matter operational time of separator high or low. The reason might be attributed to strong shear force and centrifugal force provided by hydrocyclone separator. Therefore, the inlet water velocity, a factor of shear stress, was studied. The medium water velocity of 0.3 m/s contributed to appropriate tangential velocity and static pressure, reaching the optimal granular separation efficiency that was larger than 97% for the particle diameter over 400 μm. Besides, carrier particles in previous studies were summarized and found to enhance AGS formation in short time (15 to 54 days). When they were combined with hydrocyclone separator for continuous AGS cultivation, the carrier particles with large particle size (GAC, ceramsite, etc) were proposed to be used, instead of biochar or graphite oxide nanoparticle. This study explored the feasibility of hydrocyclone separator to culture AGS, which is helpful to realize the continuous AGS cultivation.
... Low SVI implied a lower footprint and could save the construction land space. This result was also consistent with many studies on the sludge system that was published previously, SVI in the sludge system was stable in the range of 30-50 mL/g [28,29,31,32]. Recently, much research paid attention on minimizing the formation time of aerobic granulation system. ...
In this study, coffee husk was used as input raw material to produce biochar by slow pyrolysis process at 350 °C for 60 min. Coffee husk biochar with the size from 0.2 to 1.0 mm was introduced into sequencing batch reactor (SBR) system to evaluate the granulation process of activated sludge together with chemical oxygen demand (COD) and ammonium removal efficiency. Coffee husk biochar in the experiment acted as a bio carrier to promote the formation of the granular sludge in the system. Synthetic wastewater used in this study had COD/total nitrogen (C/N) ratio was adjusted gradually reduced from the optimal ratio of 20/1 to low C/N ratio of 3/1. In about 3 weeks of continuous operation, the granular sludge was initially formed with small size (less than 1 mm) and then gradually increased in bigger size and was stable in the size of 2–3 mm for long operation time (over 90 days). The treatment efficiency of COD and ammonium in the system was maintained (COD treatment efficiency was 90% and ammonium was nearly 70%). The results indicated that granular sludge formation process also possessed sludge volume index (SVI) reduction dramatically, sludge settled quickly and reduced the amount of sludge discharged. Therefore, using biochar could be a potential effective method to enhance granulation of activated sludge in SBR system for treating low C/N ratio wastewater.
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