Search

Browse

• Communities
• Authors
• Year
• Titles
• Subjects

My Space

• Login

Application of primary filtration systems for the reduction of energy requirements and for the management of increased loading in activated sludge plants

Tsamoutsoglou Konstantinos

Full record

---

Summary

In recent years, energy use in Wastewater Treatment Plants (WWTPs) has increased due to the application of advanced wastewater and sludge treatment methods as well as the management of higher volumes of waste. Many WWTPs operate with increased hydraulic flows or increased inlet load, resulting in incomplete wastewater treatment. The phenomenon is intense during the summer months, in WWTPs serving tourist areas. Innovative primary filtration systems for the treatment of urban wastewater with low cost and energy could be a solution to the above-mentioned problems. The innovation of primary filtration systems lies in the early removal of suspended solids from raw wastewater, before their entry into the aeration tank. In this way, existing and new WWTPs can be upgraded, without the need for conventional expansion. Two such pilot plants with maximum hydraulic capacity of 2,500 and 1,800 m3/d have been designed and installed in the WWTP of Marpissa (Greece) and Kyperounda (Cyprus), respectively. The pilot units consist in series of: microsieves and Continuous Backwash Upflow Media Fitlers (CBUMFs), while the condensate of the CBUMFs is treated in a lamella clarifier. In this way, the two WWTPs were upgraded so that they can accept an increased entry load, while also reducing their energy expenditure. However, both WWTPs plan to expand the sewerage network resulting in an increase in the inlet flow rate. Specifically, the main objectives of the doctoral thesis are: i) the design and construction of primary filtration systems with the processes of microsieving, sand filtration and lamellar sedimentation, ii) the investigation and evaluation of the efficiency of microsieving, sand filtration and lamellar sedimentation in raw wastewater, iii) the modeling and creation of software for microsieving and sand filtration technologies, iv) the economic evaluation of the pilot systems in the WWTPs of Marpissa and Kyperounda and v) the investigation of the adoption of primary filtration systems by WWTPs in Greece and Cyprus and vi) the quantification of the estimated benefits in the downstream biological process of overloaded WWTPs using microsieving and sand filtration technologies. The average percentage removals of Total Suspended Solids (TSS), Biochemical Oxygen Demand (BOD5), and Chemical Oxygen Demand (COD) with combined treatment, microsieving (pore opening 250 μm) followed by sand filtration, were calculated to be 52 ± 2 %, 46 ± 7 %, 43 ± 3 % in the WWTP of Kyperounda, respectively. By adding coagulants ((Polyaluminum Chloride (PAC))) to the CBUMF the mean percentage removals of TSS, BOD5 and COD with combined treatment (microsieving followed by sand filtration) were calculated to 72 ± 1 %, 52 ± 5% και 60 ± 5 %. Primary filtration systems can remove 10% to 23% of the total Kjeldahl nitrogen from raw wastewaster. However, the range of total phosphorus removal achieved by treating wastewater using microsieving (with a pore opening of 250 μm) and sand filtration technologies was 5% to 18% in the Kyperounda WWTP. The microsieve installed at WWTP Marpissa accomplished a removal of suspended solids of 40-58% without the usage of coagulants. In addition, microsieves produce Primary Sieved Solids (PSS) with a solids content over 30%. Additionally, the experimental data and model predictions exhibited a high degree of concordance (R2> 98). In addition to evaluating of the innovative technologies, the experimental data was used to develop a wastewater process simulation software. The software can provide a preliminary design of the primary filtration systems the and models the process, allowing for the implementation of innovative solutions on a larger scale. The software offers additional data regarding the estimated reduction in the energy needs of WWTPs through the use of primary filtration systems.The estimated cost for the complete treatment of wastewater with the implementation of primary filtration in the existing WWTP of Marpissa was estimated at 0.32 €/m3. However, the cost for upgrading the Marpissa WWTP with a conventional expansion (expansion of the existing biological treatment) was estimated at 0.48 €/m3. For the upgrading of the Kyperounda WWTP, the cost for the complete treatment of wastewater by primary filtration was estimated at 0.88 €/m3. On the other hand, the cost of conventional expansion (expansion of the existing biological treatment) was determined equal to 1.64 €/m3 for WWTP Kyperounda. Regarding the adoption of primary filtration systems by greek and cypriot WWTPs, the sample displayed a specific interest in implementing these systems. Investigating the effect of primary filtration systems on downstream biological treatment of overloaded WWTPs can result in significant reductions in the volume (m3) of aeration tanks (15-55%), the required oxygen demand (kg O2/h) for BOD5 removal and nitrification (14-52%), the amount (t/d) of secondary sludge (19-66%), and the energy consumption (kWh/m3) of aeration tanks (9-54%). Primary filtration systems can offer a sustainable technological approach to more efficient wastewater treatment, effectively addressing the problems of overload, while reducing the operating costs of small and large scale WWTPs.

Available Files

Services