Rotating Biological Contactor Research Articles

Modification and Performance of a Rotating Biological Contactor for the Rectification of Synthetic Auramine O dye Wastewater

The disposal of domestic and industrial wastewater into the drainage/atmosphere without treatment is a major source of pollution that endangers the health of the population and needs to be controlled. Despite long been used as a secondary treatment strategy for wastewater, conventional rotating biological contactor (RBC) suffers from the drawbacks of limited surface area for the growth of biofilms. There are persistent problems of less oxygenation capacity, and inefficient mixing resulting in inadequate mass transfer. To address these issues conventional RBC has been modified in the present study by replacing a bank of discs using a rotating drum. The use of a rotating drum in RBC enhanced the biofilm attachment surface area up to 2.29 m2 (?108.2% higher than conventional RBC), thereby improving the working performance. To prevent the dissolved oxygen as a limiting factor, four small aerators were placed as supplement aeration system in the wastewater collection tank of modified RBC. To prevent the influence of atmospheric temperature on biological process, a blast-proof aquarium glass heater was placed in the tank. For experimental work, a 700 ppm pretreated synthetic solution of Auramine-O dye as wastewater was utilized. A constant level of percentage variation in biological oxygen demand (BOD) removal efficiency was observed after 15 days of the experiment. After day-15, the MLSS concentration increased to 2960 mg/L, and the BOD concentration reduced to 12.85 mg/L, resulting in a reduction of 89.86% in BOD, indicating the meeting of effluent discharge standards.

Optimization of operational parameters using RSM, ANN, and SVM in membrane integrated with rotating biological contactor

Membrane fouling is a critical bottleneck to the widespread adoption of membrane separation processes. It diminishes the membrane permeability and results in high operational energy costs. The current study presents optimizing the operating parameters of a novel rotating biological contactor (RBC) integrated with an external membrane (RBC + ME) that combines membrane technology with an RBC. In the RBC + ME, the membrane panel is placed external to the bioreactor. Response surface methodology (RSM) is applied to optimize the membrane permeability through three operating parameters (hydraulic retention time (HRT), rotational disk speed, and sludge retention time (SRT)). The artificial neural networks (ANN) and support vector machine (SVM) are implemented to depict the statistical modelling approach using experimental data sets. The results showed that all three operating parameters contribute significantly to the performance of the bioreactor. RSM revealed an optimum value of 40.7 rpm disk rotational speed, 18 h HRT and 12.4 d SRT, respectively. An ANN model with ten hidden layers provides the highest R2 value, while the SVM model with the Bayesian optimizer provides the highest R2. RSM, ANN, and SVM models reveal the highest R-square values of 0.97, 0.99, and 0.99, respectively. Machine learning techniques help predict the model based on the experimental results and training data sets.

Biological Treatment of Industrial Wastewater

The objective of this study is to explore in depth the biological treatment technologies for industrial wastewater and to analyze their application and development with the aim of improving the efficiency of industrial wastewater treatment, reducing costs, and minimizing the adverse effects on the environment. Specifically, it includes: systematically summarizing and comparing the current common biological treatment technologies for industrial wastewater, analyzing their advantages and disadvantages, scope of application, and effectiveness, in order to improve the understanding and control of the biological treatment process. Biofilm treatment technologies include fluidized bed biofilm reactor (FBBR), membrane biofilm reactor (MBfR), moving bed biofilm reactor (MBBR), and rotating biological contactor (RBC). Further research and innovation are needed to improve treatment efficiency, reduce energy consumption and anaerobic treatment, control membrane pollution and degrade difficult-to-biodegrade substances.

Treatment of palm oil mill effluent using modified rotating biological contactor with organic loading rate variations

Indonesia is the world’s largest producer of palm oil or Crude Palm Oil (CPO). Palm oil production generates Palm Oil Mill Effluent (POME), which can harm the environment, if not properly treated. Untreated POME, with high Chemical Oxygen Demand (COD) levels, can lead to environmental degradations. Its high organic content and low acidity levels can also cause water pollution. This study modified the Rotating Biological Contactor (RBC) unit to treat POME, increasing the contact surface area between POME and microorganisms. It aimed to analyse the performance of the modified RBC unit, based on variations in organic loading rate (OLR). The study was conducted at a laboratory scale, with 2, 5, and 7 kgCOD/L/day organic loads. The results of this study revealed the highest percentage of removal obtained at an OLR variation of 7 kgCOD/L/day, with a removal rate of 70% for chemical oxygen demand (COD) concentration and 57% for ammonia concentration. Based on the research, the COD removal for organic loads of 7 kgCOD/L/day and 5 kgCOD/L/day decreased to 1900 mg/L and 2600 mg/L, respectively. Thus, the modified RBC unit would be more efficient with an organic load of 7 kgCOD/L/day. However, the COD concentration still did not comply with the water quality standards. Therefore, integrating the modified RBC unit with pre-treatment units, such as coagulation-flocculation, is necessary to achieve optimal effluent concentrations.

Peningkatan Produktivitas Dengan Metode Green Productivity Pada PT. Bangun Tenera Riau Desa Pantai Raja Kabupaten Kampar

PT Bangun Tenera Riau is a company engaged in the processing of oil palm fresh fruit bunches, located in Pantai Raja Village, Perhentian Raja District, Kampar Regency, Riau Province. The problem faced by PT Bangun Tenera Riau is that the company has not maximally utilized the by-products produced in the form of waste. This research aims to improve the production process by selecting alternative solutions to increase and enhance the initial green productivity index value so that productivity can increase and the impact on the environment can be reduced. The method used in this research is the green productivity method. Based on the environmental performance indicator (EPI) calculation, it is known that the value of biological oxygen demand (BOD) liquid waste has a deviation of -0.63% and an EPI value of -0.16 which exceeds the waste quality standard based on Kep-51 / MENLH / 1995 so that it is necessary to improve the quality of waste through alternative solutions. The alternative solution chosen is an anaerobic biogas reactor and rotating biological contactor (RBC) used to improve waste quality and company productivity. The study's results using the green productivity method obtained an average final total productivity of 1.31 with the initial value of the average productivity in each month being 1.17. The productivity value of the company increased by 0.21 with the efficiency of improving the quality of waste by BOD by 96.81% and converting liquid waste into biogas which is beneficial to the community

Microbial interactions and nitrogen removal performance in an intermittently rotating biological contactor treating mature landfill leachate

Developing efficient landfill leachate treatment is still necessary to reduce environmental risks. However, nitrogen removal in biological treatment systems is often poor or costly. Studying biofilms in anoxic/aerobic zones of rotating biological contactors (RBC) can elucidate how microbial interactions confer resistance to shock loads and toxic substances in leachate treatment. This study assessed the nitritation-anammox performance in an intermittent-rotating bench-scale RBC treating mature leachate (diluted). Despite the leachate toxicity, the system achieved nitritation with an efficiency of up to 34 % under DO values between 0.8 and 1.8 mg.L−1. The highest average ammoniacal nitrogen removal was 45.3 % with 10 h of HRT. The 16S rRNA sequencing confirmed the presence of Nitrosonomas, Aquamicrobium, Gemmata, and Plantomyces. The coexistence of these bacteria corroborated the selective pressure exerted by leachate in the community structure. The microbial interactions found here highlight the potential application of RBC to remove nitrogen in landfill leachate treatment.

Mathematical modeling and simulation of oxygen mass transfer in rotating biological contactor (RBC) for bacterial cellulose production

The Rotary Biological Contact (RBC) reactor has a unique aeration system that provides a moving bed for easy and efficient oxygen transfer within the system to overcome the limitations of stationary culture in bacterial cellulose (BC) production. In most cases, oxygen mass transfer is the limiting factor of an aerobic process, hence the changes in the oxygen mass transfer coefficient within the system have been given special attention. In this study, the RBC bioreactor producing BC was modeled based on one-dimensional oxygen mass transfer in the direction perpendicular to the surface of the discs. The Monod kinetic model has been used to express cell growth. Simulation of the mathematical model was done based on the numerical solution with finite difference method in MATLAB software. Sensitivity analysis was performed to investigate the effect of changing different system parameters in RBC modeling. The simulation results showed that with the increase in angular velocity, the oxygen transfer coefficient and subsequently the mass transfer rate increase. Also, at a certain angular velocity, the oxygen mass transfer coefficient increases with the increase of immersion depth. The best disk rotation speed considering other parameters as well as the laboratory results was 13 rpm with a 45% indentation percentage and the optimal distance between the disks was 1.5 cm.

Comparison of typical nitrite oxidizing bacteria suppression strategies and the effect on nitrous oxide emissions in a biofilm reactor

In mainstream partial nitritation/anammox (PN/A), suppression of nitrite oxidizing bacteria (NOB) and mitigation of N2O emissions are two essential operational goals. The N2O emissions linked to three typical NOB suppression strategies were tested in a covered rotating biological contactor (RBC) biofilm system at 21 °C: (i) low dissolved oxygen (DO) concentrations, and treatments with (ii) free ammonia (FA), and (iii) free nitrous acids (FNA). Low emerged DO levels effectively minimized NOB activity and decreased N2O emissions, but NOB adaptation appeared after 200 days of operation. Further NOB suppression was successfully achieved by periodic (3 h per week) treatments with FA (29.3 ± 2.6 mg NH3-N L−1) or FNA (3.1 ± 0.3 mg HNO2-N L−1). FA treatment, however, promoted N2O emissions, while FNA did not affect these. Hence, biofilm PN/A should be operated at relatively low DO levels with periodic FNA treatment to maximize nitrogen removal efficiency while avoiding high greenhouse gas emissions.

Remoción de materia orgánica presente en aguas residuales de una planta farmacéutica mediante un RBC (contactor biológico rotatorio)

A RBC (Rotating Biological Contactor) system is a technology using a biological process by which microorganisms present in wastewater arefixed to partially-submerged parallel rotating discs forming a biofilm through bioaugmentation processes. This technology allows for the removal of contaminating organic matter from the water improving treatment processes. In this research work, a laboratory-scale RBC composed of four discs submerged approximately 40 % in a volume of 1 l (0.001 m3) was used for the purpose of reducing high levels of COD and BOD contained in the wastewater of a pharmaceutical plant with the aid of two different microbial consortiums. An initial characterization of COD and BOD of the wastewater sample was carried out in order to compare with six samples obtained from the reactor in operation. A maximum COD removal of 2 560 mg O2/l was obtained which, although very high, is beyond of the permissible limits allowed by Colombian law ( ordinance 0631 of 2015) but is significant because it represents an efficient removal percentage of 99.67 % with respect to the values obtained at the initial characterization

A Review of Rotating Biological Contactors for Wastewater Treatment

A rotating biological contactor (RBC) is a type of attached-growth biological wastewater treatment system and a widely used biological wastewater treatment technology. It employs a series of rotating discs to support microbial growth and promote the removal of pollutants from wastewater. RBC is widely recognized for its simplicity of design, high reliability, and low energy consumption. It has been used in various applications, from small-scale decentralized systems to large municipal wastewater treatment plants. The current review provides an overview of RBC bioreactors, design parameters, and the factors that influence biological performance, such as hydraulic retention time, sludge retention time, organic loading rate, disc rotational speed, and temperature. The review also highlights the advantages and disadvantages of RBCs compared with other wastewater treatment technologies and discusses their role in sustainable environmental performance. The future prospects of RBC are also discussed, including integration with other technologies, such as membrane filtration and potential use in resource recovery. The review explores the application of RBC in decentralized wastewater treatment and the potential to provide sustainable solutions for wastewater management in rural and remote areas. Overall, RBC remains a promising option for effective and efficient wastewater treatment, particularly in situations where simplicity, reliability, and low energy consumption are desired.

Performance of rotating cage biological contactors based on the partial nitrification of immobilized bioactive fillers

The rotating cage biological contactors (RCBC) is based on the partial nitrification immobilization of bioactive fillers, incorporating the advantages of traditional the rotating biological contactor (RBC). The RCBC is more energy-efficient, with higher ammonia oxidation rate (AOR) and nitrite accumulation rate (NAR) levels compared to the RBC Under the conditions of different rotational speeds and immersion rates of an RCBC, the volumetric oxygen transfer coefficient (KLa) was measured. The experimental results show that these two factors significantly affected the KLa of the reactor, which ranged from 1.08 to 42.02 h−1. Regarding long-term ammonia oxidation performance, the RCBC can successfully start partial nitrification in only 5 days. After stable operation, the AOR was 23.34 ± 0.55 mg (L·h)−1, with an NAR of 93.42 ± 0.84 %. This indicates a good adaptability to variations in influent ammonia nitrogen (NH4+-N) in the range of 95.92–403.14 mg·L−1 and good resistance to free nitrous acids (FNA). In addition, high-throughput sequencing analysis showed that the operation mode of the RCBC could effectively inhibit the growth of nitrite-oxidizing bacteria (NOB) in immobilized bioactive fillers, and the internal oxygen-limited environment provided favorable conditions for reducing the relative abundance and activity of NOB. In this study, a partial nitrification device was established by immobilized bioactive fillers in the form of an RCBC for the first time, providing a partial nitrification technology without aeration.

Biofilm-based technology for industrial wastewater treatment: current technology, applications and future perspectives.

The microbial community in biofilm is safeguarded from the action of toxic chemicals, antimicrobial compounds, and harsh/stressful environmental circumstances. Therefore, biofilm-based technology has nowadays become a successful alternative for treating industrial wastewater as compared to suspended growth-based technologies. In biofilm reactors, microbial cells are attached to static or free-moving materials to form a biofilm which facilitates the process of liquid and solid separation in biofilm-mediated operations. This paper aims to review the state-of-the-art of recent research on bacterial biofilm in industrial wastewater treatment including biofilm fundamentals, possible applications and problems, and factors to regulate biofilm formation. We discussed in detail the treatment efficiencies of fluidized bed biofilm reactor (FBBR), trickling filter reactor (TFR), rotating biological contactor (RBC), membrane biofilm reactor (MBfR), and moving bed biofilm reactor (MBBR) for different types of industrial wastewater treatment. Besides, biofilms have many applications in food and agriculture, biofuel and bioenergy production, power generation, and plastic degradation. Furthermore, key factors for regulating biofilm formation were also emphasized. In conclusion, industrial applications make evident that biofilm-based treatment technology is impactful for pollutant removal. Future research to address and improve the limitations of biofilm-based technology in wastewater treatment is also discussed.

Dairy Wastewater Treatment with Rotating Biological Contactor as Secondary unit and use of Treated Effluent for Agriculture

Rotating Biological Contactor (RBC) is a biological fixed film treatment method that can be applied as part of secondary treatment for wastewater treatment. The present investigation was conducted on dairy wastewater treated by employing RBC as a secondary biological unit, which demonstrated encouraging results. Wastewater 3-day BOD was reduced to 85 mg/L from the influent BOD of 995 mg/L and COD from 1220 mg/L to 130 mg/L. Overall efficiency accomplished by RBC was 91.5% for BOD removal and 89.3% for COD reduction. The treated waste was then used for irrigation of soy and corn crops. Results exhibited an increase in organic matter from 0.262% to 0.395% for corn and 0.416 for soya, whereas available total nitrogen, phosphorus, and potassium as nutrients also increased compared to the regular groundwater application for irrigating the crop. Further, crop yield was also higher than normal, exhibiting advantages drawn from the application of treated wastewater for irrigation.

Enhanced treatment effect and universality of novel ARAO coupling process on municipal sewage: A pilot study

Under the impending demand of wastewater treatment plants (WWTPs) upgrading and reconstruction, it is feasible to propose a new process with low cost and high efficiency based on traditional process. Novel anaerobic-RBC-anoxic-oxic (ARAO) process was obtained after coupling traditional anaerobic-anoxic-oxic (A2/O) process with rotating biological contactor (RBC). Compared to traditional A2/O process, ARAO process has more efficient municipal wastewater treatment effect. Within 40 days of continuous operation, the average removal rates of COD, NH4+-N, TN and TP of sewage by ARAO process are 87%, 87%, 75% and 87%, respectively. The optimal operating conditions of ARAO process are the mixed liquor reflux ratio (MLRR) of 200%, the mixed liquor suspended solids (MLSS) of 3500–4500 mg/L, the dissolved oxygen (DO) concentration of 2–3 mg/L and the hydraulic retention time (HRT) of 6 h. The enhanced enzyme activity of ARAO process compared with A2O was determined through extracellular enzyme activity (EEA) and extracellular polymeric substances (EPS), and the microbial abundance and dominant species were further analyzed through high-throughput sequencing. The three-dimensional fluorescence measurement results showed a significant improvement in wastewater treatment efficiency. In addition, ARAO process has good adaptability to low temperature wastewater, low concentration wastewater and high concentration wastewater, which provides a good reference for the upgrading and reconstruction of WWTPs in the future.

Performance Effectiveness of Communal Wastewater Treatment Plant as an Effort to Control Pollution of the Gajah Wong River, Yogyakarta

The Gajah Wong River receives wastewater from the high population of Sleman Regency, including agricultural activities and home industries that contain organic pollutants. High organic pollutants cause dissolved oxygen depletion in waters that can threaten the lives of various aquatic biota. The construction of a communal wastewater treatment plant (WWTP) for handling domestic wastewater is an effort to control river pollution. The effectiveness of WWTP performance based on key parameters is continuously monitored, which is the purpose of this research. Surveys on 4 (four) communal WWTPs (Ngudi Mulyo, Wahana Bina Lingkungan, Tirto Mili, and Karya Asri Ambarukmo) were conducted in February – April 2021 with the key parameters observed were pH, BOD5, COD, and NH3. Sampling wastewater by grab sampling at each inlet and outlet of the WWTP using ABR (Anaerobic Baffled Reactor) and RBC (Rotating Biological Contactor) technology 6 times. The results provide an overview of the quality characteristics of wastewater that has been treated (outlet) at the Ngundi Mulyo WWTP (NH3 16.55 mg/L, BOD5 32.53 mg/L, COD 213.52 mg/L, pH 5) Wahana Bina Lingkungan (NH3 29.85 mg/L, BOD5 262.36 mg/L, pH 6-7), Tirto Mulyo (NH3 20.42 mg/L, BOD5 66.67 mg/L, COD 248.7 mg/L, pH 6-7) and Karya Asri Ambarukmo (NH3 21.60 mg/L, BOD5 252.64 mg/L, pH 6-7). These results reveal that the performance of the four WWTPs is still low and has not been effective in reducing COD and NH3 parameters, except that BOD5 reaches the required quality standard, and the processed wastewater still has the potential to reduce the water quality of the Gajah Wong River. This result is also a signal for WWTP managers to improve the processing process in each of these WWTPs.

Waste Water Treatment Installation Planning Industrial Know in Aerobic Using Rotating Biological Contactors (RBC) (Study Case at “Sari Murni” Tofu Factory, Krajan Village, Mojosongo Village, Surakarta City)

The planned advanced processing technology is aerobically using Rotating Biological Contactors (RBC). The research method used was la iterature study, in-depth interviews, and direct observation to the Sari Murni tofu factory to determine the existing conditions of the existing Wastewater Treatment Plant (IPAL), as well as to determine the discharge and characteristics of the tofu wastewater. From the results of observations in the field, it is known that the maximum discharge of tofu wastewater produced every day is 25 m3 with an average BOD parameter value of 200 mg/L. Furthermore, the researchers calculated the required RBC dimensions so that the BOD parameter value could be below standard (<150 mg/L). Based on the calculation results, it can be seen that the surface area of ​​the Rotating Biological Contractors (RBC) required is 450 m2, the number of disks required is 131 pieces, and the length of the Rotating Biological Contractors (RBC) rotor required is 2.5 meters.

Removal of N and P in a Rotating Biological Contactor Plant: Case Study Agnita, Romania

The wastewater treatment plant of Agnita, Romania was designed with a rotational biological contactor system for a population of approximately 9500, but for environmental protection reasons it must comply with regulations concerning nitrogen and phosphorus designed for larger communities. In order to achieve the prescribed limits for these pollutants, we have used a 40% FeCl3 solution, continuously added to the distributor, without changes in flow or equipment. Its use boosts the removal of ammonia nitrogen, and phosphorus, bringing them within the limits and with reasonable cost. To determine the ferric chloride to be used we considered, aside from the pollutant load, the water temperature, and introduced a new parameter: specific removal power that enabled us to optimize the volume of FeCl3. A major contribution to nitrogen removal was achieved by the denitrification bacteria favored by the presence of ferric ions, which also precipitate phosphorus. The results of this study, performed since September 2021, enable us to continue to use this method and enlarge its application to other plants owned by the local operator.

New insight for purifying polluted river water using the combination of large-scale rotating biological contactors and integrated constructed wetlands in the cold season

Ecological treatment technologies, applied to deal with polluted river water in the low temperature season, remain limited. In this study, a new insight was put forward for purifying polluted river water using a combination system (CS) of large-scale rotating biological contactors (RBCs) and integrated constructed wetlands in autumn and winter. The treatment performance, average removal contribution (RC), nitrification and denitrification rates, microbial community structure, and ecosystem service value were considered to estimate the combination system. Results revealed that the average removal efficiencies of ammonium (NH4+–N), total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD) reached 93.9%, 20.8%, 36.5%, and 37.1%, respectively. The combination system showed excellent removal efficiency of NH4+–N regardless of the effect of low temperature. The maximum values of nitrification and denitrification rates were 59.57 g N/(m3·d) and 0.78 g N/(m2·d), respectively. Considerable differences in bacterial community diversity, richness and relative abundance of functional microbes were observed in the main treatment units, resulting in different average RC to pollutants. The unit capital cost of CS purifying polluted river water was 260 USD/m3 and the operation and maintenance cost was 0.144 million USD/yr. Meanwhile, the ecosystem service value of the CS was 0.334 million USD in autumn and winter. CS not only possessed excellent pollutant purifying efficiencies, but also achieved high ecological service value in the cold season.

Ecological restoration for the Liangtan river by Rotating biological contactors combined with hybrid constructed wetlands

Rotating biological contactors (RBCs) were first used as pretreatment units for hybrid constructed wetlands (HCWs) in practical engineering to treat polluted river water. The experimental results during 2019–2021, except the period of global COVID-19 pandemic (January to April, November and December in 2020), indicated the average removal efficiencies of ammonia nitrogen (NH4+–N), total phosphorous (TP), and chemical oxygen demand (COD) were 95.06%, 41.03%, and 45.46%, which met the Chinese Environmental Quality Standards Ⅰ, Ⅲ, Ⅳ (CEQS Ⅰ, Ⅲ, Ⅳ), respectively. RBCs and HCWs had synergistic and complementary effects on purification efficiency, especially on nitrogen removal. The remarkable nitrification efficiency of RBCs was not influenced by temperature and influent loads. The relative abundances of microorganisms at HCWs in cold seasons were comparable to that in warm seasons, which promoted the recovery of decontamination efficiency after overwintering. These results support RBCs combined with HCWs (R-HCWs) is an effective polluted river purification process, providing a new perspective on water ecological restoration.

Niche differentiation and symbiotic association among ammonia/nitrite oxidizers in a full-scale rotating biological contactor

Although the distribution of ammonia/nitrite oxidizers had been profiled in different habitats, current understanding is still limited regarding their niche differentiation in the integrated biofilm reactors, the symbiotic associations of ammonia/nitrite oxidizers, as well as the parasitic interaction between viruses and those functional organisms involved in the nitrogen cycle. Here, the integrated metagenomics and metatranscriptomics are applied to profile the ammonia/nitrite oxidizers communities and transcriptional activities changes along the flowpath of a concatenated full-scale rotating biological contactor (RBC) (frontend Stage-A and backend Stage-B). 19 metagenome-assembled genomes (MAGs) of ammonia/nitrite oxidizers were recovered by using a hybrid assembly approach, including four ammonia-oxidizing bacteria (AOB), two ammonia-oxidizing archaea (AOA), two complete ammonia oxidation bacteria (comammox), eight nitrite-oxidizing bacteria (NOB), and three anaerobic ammonium oxidation bacteria (anammox). Diverse AOB and anammox dominated Stage-A and collectively contributed to nitrogen conversion. With the decline of ammonia concentration along the flowpath, comammox and AOA appeared and increased in relative abundance in Stage-B, accounting for 8.8% of the entire community at the end of this reactor, and their dominating role in nitrogen turnover was indicated by the high transcription activity of their corresponding function genes. Moreover, the variation in the abundance of viruses infecting ammonia and nitrite oxidizers suggests that viruses likely act as a biotic factor mediating ammonia/nitrite oxidizer populations. This study demonstrates that complex factors shaped niche differentiation and symbiotic associations of ammonia/nitrite oxidizers in the RBC and highlights the importance of RBCs as model systems for the investigation of biotic and abiotic factors affecting the composition of microbiomes.