Sludge Reduction Process Research Articles

The Comparison of Biological Sludge Reduction Processes

The Comparison of Biological Sludge Reduction Processes

The Comparison of Biological Sludge Reduction Processes

The Comparison of Biological Sludge Reduction Processes

Performance Verification of Biological Sludge Reduction Process Modeling Using ASM-Based Models

Performance Verification of Biological Sludge Reduction Process Modeling Using ASM-Based Models

Techno-economic evaluation of thermal treatment, ozonation and sonication for the reduction of wastewater biomass volume before aerobic or anaerobic digestion

Aerobic and anaerobic digestions were compared with different sludge reduction processes such as ultrasonic, ozone, and thermal treatments. Each treatment was tested under the following conditions to improve batch aerobic or anaerobic digestion: ultrasound ( 200,000 kJ kgT S 0 − 1 ) , thermal (40 °C, 60 °C, 90 °C for 90 min, 120 °C 15 min, 1 bar), and ozonation ( 0.1 g O 3 gT S 0 − 1 ) . The different pretreatments induced organic matter solubilisation and intrinsic sludge reduction (total suspended solids): ultrasound (47%), thermal 90 °C (16%), ozone (15%), thermal 60 °C (9%), thermal 40 °C (5%), autoclave (120 °C) (4.2%). TSS (and also VSS) solubilisation were found to be highly correlated to the pretreatment ability to break the flocs rather than to specific energy input. The total values of TSS reduction ranged from 57% to 71% under aerobic conditions and from 66% to 86% under anaerobic conditions. TSS solubilisation after pretreatment can be considered as a predictive parameter of sludge volume reduction enhancement after aerobic or anaerobic digestion while specific energy input did not show anything or negligible impact. In our experimental conditions, ultrasound and ozone led to the best TSS removal improvement after both aerobic (30% and 20%) and anaerobic digestion (20%). Ultrasonic and ozone pretreatments prior to aerobic or anaerobic digestion led to the best reduction of the specific energy required for removing 1 kg of TSS compared to the control. Anaerobic digestion was globally more effective (compare to aerobic digestion) in enhancing sludge production reduction.

The Use of ASM based Models for the Simulation of Biological Sludge Reduction Processes

The advent of sludge reduction technologies that are capable of significantly reducing sludge production from wastewater treatment facilities has garnered much interest from the wastewater treatment profession. As part of CH2M HILL's effort to better understand the mechanisms behind these processes, a research effort was completed that was focused on developing an ASM based model which adequately reflects the performance of the Cannibal® Sludge Reduction process by Siemens. A modification is proposed of the standard ASM 2d model to capture the effects of biological sludge reduction used in the Cannibal Solids Reduction process. This model is able to capture the essential aspects of this system and provides a more quantitative method for the sizing and performance of these types of systems. The primary components of this modification include separation of the microbiological decay products from the traditional particulate inert fraction, and into a separate particulate decay product for aerobic/anoxic microbes (XDAA). A new process rate is included in the model for anaerobic “hydrolysis” of XDAA to XS. The results were compared against the experience of Siemens on a wide range conditions. The results indicate that this model predicts operating characteristics of the Cannibal process with a reasonable level of accuracy.

Assessment of physiological state of microorganisms in activated sludge with flow cytometry: application for monitoring sludge production minimization

Many sludge reduction processes have been studied for the minimization of sludge production in biological wastewater treatment. The investigations on most of these processes have monitored the increase of the soluble chemical oxygen demand, the sludge mass reduction, or the decrease of the floc size, but little information has been obtained on cell lysis and the change of the biological cell activity. However, employing any strategy for reducing sludge production may have an impact of microbial community in biological wastewater treatment process. This impact may influence the sludge characteristics and the quality of effluent. The objective of this study concerns the determination of the physiological state of activated sludge microorganisms during a sludge minimization process. A thermal treatment at 80 degrees C for 5, 20, 40 and 60 min was chosen in this study. Staining bacteria with CTC and SYTOX green was used to evaluate biological cell activity and viability of cell types contained in activated sludge, respectively. The monitoring of cell activity and viability was performed using flow cytometry (FCM) analysis before and after thermal treatment of activated sludge. Results indicated an increase in the number of permeabilized cells and a decrease in the number of active cells, subsequent to the thermal treatment. The study also confirms the potential of FCM to successfully evaluate the physiological heterogeneity of an activated sludge bacterial population. Moreover, the experimentally observed correlations between the FCM results and the organic matter solubilization in activated sludge samples during thermal treatment revealed that the increase in the soluble organic matter concentration was predominantly due to an intracellular material release. Identifying the increase in activated sludge hydrolysis requires a precise knowledge of the involved mechanisms, and this study indicated that the FCM, used in conjunction with specific probes, could be a useful tool.

Advanced sludge reduction and phosphorous removal process

An advanced sludge reduction process, i. e. sludge reduction and phosphorous removal process, was developed. The results show that excellent sludge reduction and biological phosphorous removal can be achieved perfectly in this system. When chemical oxygen demand ρ (COD) is 332 – 420 mg/L, concentration of ammonia ρ(NH3-N) is 30 – 40 mg/L and concentration of total phosphorous ρ(TP) is 6.0 – 9.0 mg/L in influent, the system still ensures ρ(COD)<23 mg/L, ρ(NH3-N)<3.2 mg/L and ρ(TP)<0.72 mg/L in effluent. Besides, when the concentration of dissolved oxygen ρ(DO) is around 1.0 mg/L, sludge production is less than 0.140 g with the consumption of 1 g COD, and the phosphorous removal exceeds 91%. Also, 48.4% of total nitrogen is removed by simultaneous nitrification and denitrification.

Operation of a new sewage treatment process with technologies of excess sludge reduction and phosphorus recovery

This paper shows the potential application of a new sewage treatment process with technologies of excess sludge reduction and phosphorus recovery. The process incorporated ozonation for excess sludge reduction and crystallisation process for phosphorus recovery to a conventional anaerobic/oxic (A/O) phosphorus removal process. A lab-scale continuous operation experiment was conducted with the ratio of sludge flow rate to ozonation tank of 1.1% of sewage inflow under 30 to 40 mgO3/gSS of ozone consumption and with sludge wasting ratio of 0.34% (one-fifth of a conventional A/O process). Throughout the operational experiment, a 60% reduction of excess sludge production was achieved in the new process. A biomass concentration of 2300 mg/L was maintained, and the accumulation of inactive biomass was not observed. The new process was estimated to give a phosphorus recovery degree of more than 70% as an advantage of excess sludge reduction. The slight increase in effluent COD was observed, but the process performance was maintained at a satisfactory level. These facts demonstrate an effectiveness of the new process for excess sludge reduction as well as for phosphorus recovery.

Hydroxyapatite crystallization from a highly concentrated phosphate solution using powdered converter slag as a seed material

A system for recovering phosphorus from membrane-filtrate from a sludge reduction process containing high phosphorus concentrations was developed. In this system, referred to as the completely mixed phosphorus crystallization reactor, powdered converter slag was used as a seed material. In a preliminary experiment, the optimal pH range for metastable crystallization of phosphorus from membrane-filtrate containing about 100 mg/L PO 4-P was found to be 6.6–7.0. The laboratory scale completely mixed phosphorus crystallization reactor, actually operated in pH range of 6.8–7.6 for influent 72.9 mg/L PO 4-P, achieved an average efficiency of phosphorus removal from the membrane-filtrate of 52.4% during a 30-day experiment. Mixed-liquor suspended solids (MLSS) measurements revealed that, out of 0.24 kg PO 4-P in the original membrane-filtrate fed into the reactor, 0.12 kg PO 4-P was recovered on the seed particles after 30 days. X-ray diffraction (XRD) pattern and Fourier transform infrared (FT-IR) spectra of the crystalline material deposited on the seed particles showed peaks consistent with hydroxyapatite. Scanning electron micrograph (SEM) images exhibited that finely distributed crystalline material was formed on the surfaces of seed particles. Energy dispersive X-ray spectroscopy (EDS) mapping analysis revealed that the molar composition ratio of Ca/P of the crystalline material was 1.84. The Ca/P molar ratio > 1.67 for crystalline substance might result from the presence of CaCO 3 on the crystalline surfaces. A particle size distribution analysis showed that the average particle size increased from 22 μm for the original converter slag seed particles, to 94 μm after 30 days of phosphorus crystallization. Collectively, the present results suggest that the proposed phosphorus crystallization recovery system is an effective tool for recycling phosphorus from phosphate solution.

Chemically reduced excess sludge production in the activated sludge process.

Excess sludge production from wastewater biological treatment process is highly, and the disposal of excess sludge will be forbidden in a near future, thus increased attention has been turned to look into potential technology for sludge reduction. Recently, some novel sludge reduction techniques have been developed based on chemical oxidation and metabolic uncoupling. This paper attempts to review those chemical-assisted sludge reduction processes, including sludge alkaline-thermal treatment, activated sludge-ozonation process, chlorination-combined activated sludge process, sludge reduction by metabolic uncouplers and high dissolved oxygen activated sludge process. In these combined activated sludge processes, excess sludge production can be reduced up to 100% without significant effect on process efficiency and stability. This paper would be useful when one is looking for appropriate environmentally and economically acceptable solutions for reducing or minimizing excess sludge production from wastewater biological treatment process.

Minimization of sludge production in biological processes: an alternative solution for the problem of sludge disposal

A combined system associating activated sludge and ozonation was evaluated for the treatment of urban wastewater. Experiments have shown that 70% reduction in sludge production can be reached (compared to a reference system running in low loaded conditions Y(obs) = 0.28 g VSS.g COD(-1)) by applying an ozone dosage of 0.05 g O3/g VSS(treated) Recycling of the ozonated sludge to the aeration tank induces a slight increase in effluent COD, but the biological treatment performance is maintained. Nitrification capabilities are not altered by the sludge reduction process and active biomass measurements revealed that autotrophic biomass seems to be less affected than the heterotrophs. Significant improvements in sludge settling characteristics are observed.

Process for sludge reduction in an aerobic sludge generating waste treatment system

Process for sludge reduction in an aerobic sludge generating waste treatment system

4915840 Process for sludge reduction in an aerobic sludge generating waste treatment system: Alan Rozich assigned to Bioprocess Engineering Inc

4915840 Process for sludge reduction in an aerobic sludge generating waste treatment system: Alan Rozich assigned to Bioprocess Engineering Inc