Anaerobic-aerobic Wastewater Treatment Research Articles

An Application of Anaerobic-Aerobic Combined Bioreactor Efficiency in COD Removal

Over the past few decades, anaerobic-aerobic wastewater treatment systems have been widely used in industrial and municipal wastewater treatment. This study was conducted to examine the effects of combined anaerobic-aerobic bioreactors in the removal of chemical oxygen demands (COD) while reducing phosphate concentrations in synthetic wastewater. In this project, a bioreactor with the dimensions of 10 cm × 10 cm × 80 cm with respective Kaldnes packing ratios of 90 and 30% for the anaerobic and aerobic sections was designed. A combined anaerobic-aerobic reactor’s structure made changing hydraulic retention times only possible by adjusting the volume of its aerobic and anaerobic sections. In the first case, the anaerobic and aerobic sections of the reactor occupied 30 and 50 cm of its height, respectively. The height of the anaerobic section decreases to 12.5 cm in the second case. In aerobic and anaerobic sections, pH was within a neutral range, temperature was 37°C. MLSS (mixed liquor suspended solids) was 1220 and 1030 mg/L, and attached growth was 743 and1190 mg/L respectively. In order to evaluate COD in the wastewater, three different initial phosphorus concentrations were tested: 12.8, 32.0 and 44.8 mg/L, as well as four COD: 500, 1000, 1200 and 1400 mg/L. Considering the results, COD removal is greater than 80% when the valve 2 is in the anaerobic section outlet regardless of the concentration of phosphate. In this case, the best result is for inlet COD of 500, where the reactor can eliminate more than 90%. When the COD concentration reaches 1000 to 1400 ppm, the reactor’s COD removal efficiency declines to 60%.

Design of a High-Rate Wastewater Treatment Process for Energy and Water Recovery at Biorefineries

Industrial wastewaters rich in organic carbon have potential for value generation, but conventional, low-rate, anaerobic–aerobic wastewater treatment (WWT) processes often incur significant capital expenses and energy consumption. In this study, we leveraged experimental data for biorefinery-derived wastewaters to characterize the implications of transitioning from a conventional, low-rate process to a high-rate, multistage anaerobic process. We designed and simulated these WWT processes across seven first- and second-generation (1G/2G) biorefineries and evaluated the implications for biorefinery sustainability through techno-economic analysis (TEA) and life cycle assessment (LCA). Compared to the conventional design, the new process can substantially reduce capital costs and electricity usage. These improvements were particularly evident for 2G biorefineries, translating to 5%–13% lower minimum product selling prices (MPSPs) and 7%–135% lower 100-year global warming potentials (GWPs; the 135% reduction is due to the transition of one biorefinery from net emission [0.87 kg of CO2e·gal–1] to net sequestration [−0.31 kg of CO2e·gal–1]). Biorefineries could further reduce the MPSP through the renewable identification number (RIN) credits by upgrading and selling the biogas as renewable natural gas, but at the expense of increasing GWP. When normalized, the COD management cost ranged from $–56 to $465 per tonne of COD, indicating that wastewater could be a net source of revenue for some biorefineries.

ОЦЕНКА ЭКОЛОГИЧЕСКОЙ ЭФФЕКТИВНОСТИ ВНЕДРЕНИЯ ТЕХНОЛОГИИ АНАЭРОБНО-АЭРОБНОЙ ОЧИСТКИ СТОЧНЫХ ВОД МОЛОКОПЕРЕРАБАТЫВАЮЩЕГО ПРЕДПРИЯТИЯ

Russia The article describes the results of calculations of the environmental efficiency of the implementation of the developed biotechnology for anaerobic-aerobic wastewater treatment for a milk processing enterprise operating on the territory of the Republic of Tatarstan. With the treatment of wastewater generated at the enterprise in the amount of 200 m3 /day using the developed technology, the annual economic effect will be 147208,80 rubles. The results of calculating the energy efficiency of the operation of an anaerobic-aerobic wastewater treatment plant with the production of climate-neutral fuel - biogas are presented. Keywords: Wastewater, dairy industry, anaerobic-aerobic wastewater treatment, economic and environmental efficiency.

New Approaches in Biological Wastewater Treatment Aimed at Removal of Organic Matter and Nutrients

Abstract The article presents the developed anaerobic-aerobic wastewater treatment technologies. These technologies aimed at removing the organic matter, nitrogen and phosphorus by means of microorganisms immobilized on fibrous carrier surfaces. The results of the laboratory research show the high efficiency of milk wastewater treatment. The following degrees of reduction were achieved for the pollutant indicators: COD -86.7-93 %, total nitrogen - 96.9-97.9 %. Compared to the traditional treatment technologies applied in Ukraine, these values are high. The concentration of organic matters and biomass of not attached bacteria decreased in bioreactor chambers. When the purification process ends, a small amount of excess biomass remains; therefore, its self-oxidation and self-regulation occurs as a result of consumption by the organisms occupying higher levels of trophic chains. The use of anaerobic-aerobic bioreactors system for the treatment of wastewater enables achieving high outflow quality and prevents the suspended substances from slipping. Immobilization of microorganisms on the first stage of the technology prevents the formation of big amount of excessive sludge and removes biomass from the bioreactor, which allows the technology even for the heavily polluted wastewater. In reactors containing immobilized microorganisms, the organic matter compounds used in subsequent reactors for phosphate accumulation are split. The presented biotechnology saves electric energy, provides sufficient quality of treatment, and ensure the compliance of treated wastewater with the effluent standards.

Impact of tetracycline on the performance and abundance of functional bacteria of a lab-scale anaerobic-aerobic wastewater treatment system

The occurrence of various antibiotics in wastewater treatment systems continues to arouse extensive attention. However, the effects of low concentration of antibiotics on wastewater treatment performance and the related functional bacteria, especially under long-term operation, remain largely unknown. In this study, a lab-scale anaerobic-aerobic system was established to evaluate the impacts of 5 mg l−1 tetracycline on the performance of a lab-scale wastewater treatment system and the abundance of the related functional bacteria. The results indicated that Tc exposure had little effect (p > 0.05) on the efficiency of COD removal during the whole period of 200 days, but significantly decreased ammonia removal (p < 0.05) and accelerated sludge bulking deterioration. Although the core bacterial communities and the abundance of amoA genes in the activated sludge were not affected, the growth of Nitrospira was inhibited (p < 0.05), and Sphaerotilus was promoted by tetracycline exposure. The results of this study provide important references for the maintenance of wastewater treatment systems.

Possibilities of joint treatment of spent sugar beet pulp and waste water from a sugar factory

The possibility of joint treatment of spent sugar beet pulp and wastewater from a sugar factory was studied in this work. Works focused on processing of spent sugar beet pulp separately or together with other substrates can be found in the literature. In the case of some sugar factories, which have spare capacity in the anaerobic reactor on an anaerobic-aerobic wastewater treatment plant, joint processing of spent sugar beet pulp and wastewater from the sugar factory might be an interesting option. The results of the operation of a pilot plant of an anaerobic reactor with a capacity of 3.5 m3 are discussed. Operation of the pilot plant confirmed the possibility of cofermentation of these materials. The organic loading rate achieved in the anaerobic reactor was higher than 6 kg/(m3·d) (COD), while more than half of the load was provided by spent sugar beet pulp. The addition of sugar beet pulp decreased the concentration of ammonia nitrogen in the anaerobic reactor and it was even necessary to add nitrogen. However, the nitrogen content in sludge water depends on the C:N ratio in the processed sugar beet pulp, therefore this knowledge cannot be generalized. About 1.5 to 2-fold biogas production can be expected from the cofermentation of wastewater with sugar beet pulp in an anaerobic reactor, compared with the biogas production from just wastewater treatment.

Effects of High Circulation Ratio on Biological Nitrogen Removal in Anaerobic-aerobic Wastewater Treatment System

Effects of High Circulation Ratio on Biological Nitrogen Removal in Anaerobic-aerobic Wastewater Treatment System

Control Strategies for a Combined Anaerobic (UASB) – Aerobic (Activated Sludge) Wastewater Treatment System

This paper presents a comparative analysis among four control strategies for the control of a combined anaerobic-aerobic wastewater treatment configuration. The anaerobic stage is an Upflow Anaerobic Sludge Blanket (UASB) reactor, whereas the aerobic stage consists of the Activated Sludge (AS) process. The control variables are solids concentration in the effluent and sludge wastage rate. The proposed control strategy is considered the most reliable among them. It is based on two cascaded PI-controllers for the solids concentration in the effluent and a look-up table for the sludge wastage rate control. Experimental and simulated results are presented.

Large-Scale Anaerobic/Aerobic Treatment Plants for Wastewaters from a Molasses Distillery, a Pectin Factory, and Starch Factories

The operating data and problems of four large-scale anaerobic-aerobic wastewater treatment plants are described. Three of these plants, treating wastewaters from a molasses distillery, a wheat-starch factory, and a potato-starch factory, use fixed-film methane reactors as the anaerobic stage. Two of these reactors are filled with packed blocks of plastic material (well known from aerobic trickling filters) with a specific surface area of 150 m2/m3. The fixed-film methane reactors in the potato-starch factory use lava slag as the support media. The companies concerned produced wastewaters which fluctuate greatly in quality and quantity. To guarantee stable degradation and high COD removal, equalizing tanks and low design rates are very important. Some of the wastewaters need additional dosing of trace elements to achieve satisfactory COD removal. All full-scale experience has shown that external anaerobic sludge retention, even when using the fixed-film reactors, is important for the anaerobic system.