scholarly journals Ultrasonic pretreatment for anaerobic digestion of suspended and attached growth sludges

2019 ◽  
Vol 54 (4) ◽  
pp. 265-277 ◽  
Author(s):  
Peter Roebuck ◽  
Kevin Kennedy ◽  
Robert Delatolla
Keyword(s):  
Anaerobic Digestion ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Biogas Production ◽  
Biofilm Reactor ◽  
Municipal Wastewater Treatment ◽  
Ultrasonic Pretreatment ◽  
Conventional Activated Sludge ◽  
Digestion Kinetics ◽  
The Impact

Abstract Anaerobic digestion (AD) is a proven technology for energy production from the stabilization and reduction of sewage waste. The AD and impact of ultrasonic pretreatment of four waste activated sludges (WASs) from conventional and three non-conventional municipal wastewater treatment plants were investigated. WAS from a conventional activated sludge (CAS) system, a rotating biological contactor (RBC), a lagoon, and a nitrifying moving-bed biofilm reactor (MBBR) were pretreated with ultrasonic energies of 800–6,550 kJ/kg total solids to illustrate the impact of sludge type and ultrasonic pretreatment on biogas production (BGP), solubilization, and digestion kinetics. The greatest increase in BGP over the control of pretreated sludge did not coincide consistently with greater sonication energy but occurred within a solubilization range of 2.9–7.4% degree of disintegration and are as follows: 5% ± 3 biogas increase for CAS, 12% ± 9 for lagoon, 15% ± 2 for nitrifying MBBR, and 20% ± 2 for RBC. The effect of sonication on digestion kinetics was inconclusive with the application of modified Gompertz, reaction curve, and first-order models to biogas production. These results illustrate the unique response of differing sludges to the same levels of sonication energies. This article has been made Open Access thanks to the kind support of CAWQ/ACQE (https://www.cawq.ca).

scholarly journals Modification of municipal wastewater for improved biogas recovery

2020 ◽  
Vol 15 (3) ◽  
pp. 683-696
Author(s):  
Vaileth Hance ◽  
Thomas Kivevele ◽  
Karoli Nicholas Njau
Keyword(s):  
Anaerobic Digestion ◽  
Energy Demand ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Organic Content ◽  
Municipal Wastewater Treatment ◽  
Naoh Solution ◽  
Municipal Wastewater Treatment Plants

Abstract The energy demand, which is expected to increase more worldwide, has sparked the interest of researchers to find sustainable and inexpensive sources of energy. This study aims to integrate an energy recovering step into municipal wastewater treatment plants (MWWTPS) through anaerobic digestion. The anaerobic digestion of municipal wastewater (MWW), and then co-digestion with sugar cane molasses (SCM) to improve its organic content, was conducted at 25 °C and 37 °C. The results showed a substrate mixture containing 6% of SCM and total solids (TS) of 7.52% yielded a higher amount of biogas (9.73 L/L of modified substrate). However, chemical oxygen demand (COD) of the resulting digestate was high (10.1 g/L) and pH was not stable, and hence needed careful adjustment using 2 M of NaOH solution. This study recommends a substrate mixture containing SCM (2%) and TS (4.34%) having biogas production (4.97 L/L of modified substrate) for energy recovery from MWWTPS, since it was found to have more stable pH and low COD residue (1.8 g/L), which will not hold back the MWW treatment process. The annual generation of modified substrate (662,973 m3) is anticipated to generate about 16,241 m3 of methane, which produces up to 1.8 GWh and 8,193 GJ per annum.

scholarly journals Improving and upgrading an existing activated sludge with a compact MBBR – disc filters parallel line for municipal wastewater treatment in touristic alpine areas

2020 ◽  
Vol 15 (2) ◽  
pp. 515-527
Author(s):  
L. Desa ◽  
P. Kängsepp ◽  
L. Quadri ◽  
G. Bellotti ◽  
K. Sørensen ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Oxygen Demand ◽  
Parallel Line ◽  
Ammonium Nitrogen ◽  
Biofilm Reactor ◽  
Municipal Wastewater Treatment ◽  
Yearly Average

Abstract Many wastewater treatment plants (WWTP) in touristic areas struggle to achieve the effluent requirements due to seasonal variations in population. In alpine areas, the climate also determines a low wastewater temperature, which implies long sludge retention time (SRT) needed for the growth of nitrifying biomass in conventional activated sludge (CAS). Moreover, combined sewers generate high flow and dilution. The present study shows how the treatment efficiency of an existing CAS plant with tertiary treatment can be upgraded by adding a compact line in parallel, consisting of a Moving Bed Biofilm Reactor (MBBR)-coagulation-flocculation-disc filtration. This allows the treatment of influent variations in the MBBR and a constant flow supply to the activated sludge. The performance of the new 2-step process was comparable to that of the improved existing one. Regardless significant variations in flow (10,000–25,000 m3/d) and total suspended solids (TSS) (50–300 mg/L after primary treatment) the effluent quality fulfilled the discharge requirements. Based on yearly average effluent data, TSS were 11 mg/L, chemical oxygen demand (COD) 27 mg/L and total phosphorus (TP) 0.8 mg/L. After the upgrade, ammonium nitrogen (NH4-N) dropped from 4.9 mg/L to 1.3 mg/L and the chemical consumption for phosphorus removal was reduced.

Occurrence and fate of relevant substances in wastewater treatment plants regarding Water Framework Directive and future legislations

2012 ◽  
Vol 65 (7) ◽  
pp. 1179-1189 ◽  
Author(s):  
S. Martin Ruel ◽  
J.-M. Choubert ◽  
H. Budzinski ◽  
C. Miège ◽  
M. Esperanza ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Water Framework Directive ◽  
Municipal Wastewater ◽  
River Flow ◽  
Wastewater Treatment Plants ◽  
Quality Standard ◽  
Treated Wastewater ◽  
Municipal Wastewater Treatment ◽  
Conventional Activated Sludge ◽  
Treatment Processes

The next challenge of wastewater treatment is to reliably remove micropollutants at the microgram per litre range. During the present work more than 100 substances were analysed through on-site mass balances over 19 municipal wastewater treatment lines. The most relevant substances according to their occurrence in raw wastewater, in treated wastewater and in sludge were identified, and their fate in wastewater treatment processes was assessed. About half of priority substances of WFD were found at concentrations higher than 0.1 μg/L in wastewater. For 26 substances, potential non-compliance with Environmental Quality Standard of Water Framework Directive has been identified in treated wastewater, depending on river flow. Main concerns are for Cd, DEHP, diuron, alkylphenols, and chloroform. Emerging substances of particular concern are by-products, organic chemicals (e.g. triclosan, benzothiazole) and pharmaceuticals (e.g. ketoprofen, diclofenac, sulfamethoxazole, carbamazepine). About 80% of the load of micropollutants was removed by conventional activated sludge plants, but about two-thirds of removed substances were mainly transferred to sludge.

The impact of influent total ammonium nitrogen concentration on nitrite-oxidizing bacteria inhibition in moving bed biofilm reactor

2013 ◽  
Vol 69 (6) ◽  
pp. 1227-1233 ◽  
Author(s):  
Vojtech Kouba ◽  
Michael Catrysse ◽  
Hana Stryjova ◽  
Ivana Jonatova ◽  
Eveline I. P. Volcke ◽  
...  
Keyword(s):  
Municipal Wastewater ◽  
Nitrogen Concentration ◽  
Ammonium Nitrogen ◽  
Biofilm Reactor ◽  
Nitrite Accumulation ◽  
Municipal Wastewater Treatment ◽  
Moving Bed ◽  
Nitrite Oxidizing Bacteria ◽  
Total Ammonium ◽  
The Impact

The application of nitrification–denitrification over nitrite (nitritation–denitritation) with municipal (i.e. diluted and cold (or low-temperature)) wastewater can substantially improve the energy balance of municipal wastewater treatment plants. For the accumulation of nitrite, it is crucial to inhibit nitrite-oxidizing bacteria (NOB) with simultaneous proliferation of ammonium-oxidizing bacteria (AOB). The present study describes the effect of the influent total ammonium nitrogen (TAN) concentration on AOB and NOB activity in two moving bed biofilm reactors operated as sequencing batch reactors (SBR) at 15 °C (SBR I) and 21 °C (SBR II). The reactors were fed with diluted reject water containing 600, 300, 150 and 75 mg TAN L−1. The only factor limiting NOB activity in these reactors was the high concentrations of free ammonia and/or free nitrous acid (FNA) during the SBR cycles. Nitrite accumulation was observed with influents containing 600, 300 and 150 mg TAN L−1 in SBR I and 600 and 300 in SBR II. Once nitrate production established in the reactors, the increase of influent TAN concentration up to the original 600 mg TAN L−1 did not limit NOB activity. This was due to the massive development of NOB clusters throughout the biofilm that were able to cope with faster formation of FNA. The results of the fluorescence in situ hybridization analysis preliminarily showed the stratification of bacteria in the biofilm.

scholarly journals LCA of a Membrane Bioreactor Compared to Activated Sludge System for Municipal Wastewater Treatment

Membranes ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 421
Author(s):  
Dimitra C. Banti ◽  
Michail Tsangas ◽  
Petros Samaras ◽  
Antonis Zorpas
Keyword(s):  
Wastewater Treatment ◽  
Life Cycle ◽  
Activated Sludge ◽  
Membrane Bioreactor ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Real Data ◽  
Municipal Wastewater Treatment ◽  
Conventional Activated Sludge

Membrane bioreactor (MBR) systems are connected to several advantages compared to the conventional activated sludge (CAS) units. This work aims to the examination of the life cycle environmental impact of an MBR against a CAS unit when treating municipal wastewater with similar influent loading (BOD = 400 mg/L) and giving similar high-quality effluent (BOD < 5 mg/L). The MBR unit contained a denitrification, an aeration and a membrane tank, whereas the CAS unit included an equalization, a denitrification, a nitrification, a sedimentation, a mixing, a flocculation tank and a drum filter. Several impact categories factors were calculated by implementing the Life Cycle Assessment (LCA) methodology, including acidification potential, eutrophication potential, global warming potential (GWP), ozone depletion potential and photochemical ozone creation potential of the plants throughout their life cycle. Real data from two wastewater treatment plants were used. The research focused on two parameters which constitute the main differences between the two treatment plants: The excess sludge removal life cycle contribution—where GWPMBR = 0.50 kg CO2-eq*FU−1 and GWPCAS = 2.67 kg CO2-eq*FU−1 without sludge removal—and the wastewater treatment plant life cycle contribution—where GWPMBR = 0.002 kg CO2-eq*FU−1 and GWPCAS = 0.14 kg CO2-eq*FU−1 without land area contribution. Finally, in all the examined cases the environmental superiority of the MBR process was found.

Carbon footprints of Scandinavian wastewater treatment plants

2013 ◽  
Vol 68 (4) ◽  
pp. 887-893 ◽  
Author(s):  
D. J. I. Gustavsson ◽  
S. Tumlin
Keyword(s):  
Wastewater Treatment ◽  
Carbon Footprint ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Biogas Production ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Municipal Wastewater Treatment ◽  
Carbon Footprints ◽  
Fossil Carbon

This study estimates the carbon footprints of 16 municipal wastewater treatment plants (WWTPs), all situated in Scandinavian countries, by using a simple model. The carbon footprint calculations were based on operational data, literature emission factors (efs) and measurements of greenhouse gas emissions at some of the studied WWTPs. No carbon neutral WWTPs were found. The carbon footprints ranged between 7 and 108 kg CO2e P.E.−1 year−1. Generally, the major positive contributors to the carbon footprint were direct emissions of nitrous oxide from wastewater treatment. Whether heat pumps for effluents have high coefficient of performance or not is extremely important for the carbon footprint. The choice of efs largely influenced the carbon footprint. Increased biogas production, efficient biogas usage, and decreased addition of external fossil carbon source for denitrification are important activities to decrease the carbon footprint of a WWTP.

Elimination of organic micro-contaminants in municipal wastewater by a combined immobilized biomass reactor and solar photo-Fenton tertiary treatment

2017 ◽  
Vol 20 (1) ◽  
Author(s):  
L. Prieto-Rodríguez ◽  
I. Oller ◽  
A. Agüera ◽  
S. Malato
Keyword(s):  
Municipal Wastewater ◽  
New Technologies ◽  
Wastewater Treatment Plants ◽  
Solid Phase ◽  
Municipal Wastewater Treatment ◽  
Tertiary Treatment ◽  
Conventional Activated Sludge ◽  
Immobilized Biomass ◽  
Municipal Wastewater Treatment Plants ◽  
Micro Pollutants

AbstractMunicipal wastewater treatment plants (MWTPs) have become one of the main sources of water for potential reuse. However, some pharmaceuticals, pesticides, hormones and others organics escape conventional wastewater treatments, and therefore, new technologies must be applied to overcome the problem. This article presents an efficient alternative that combines an aerobic immobilized biomass reactor (IBR) with a solar photo-Fenton process as a tertiary treatment. Real municipal wastewater was treated in the IBR system in batch and continuous modes. Micro-pollutants were monitored by using an advanced analytical procedure consisting of pre-concentration of samples by solid phase extraction (SPE) followed by liquid chromatography coupled to mass spectrometry. Results were compared with those observed in the MWTP secondary conventional activated sludge treatment. Effluents from the IBR, operating at the maximum treatment capacity, were treated in a previously optimized solar photo-Fenton pilot plant as a tertiary treatment to entirely eliminate remnant micro-pollutants.

scholarly journals Advanced Wastewater Treatment to Eliminate Organic Micropollutants in Wastewater Treatment Plants in Combination with Energy-Efficient Electrolysis at WWTP Mainz

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3599 ◽  
Author(s):  
Oliver Gretzschel ◽  
Michael Schäfer ◽  
Heidrun Steinmetz ◽  
Erich Pick ◽  
Kim Kanitz ◽  
...  
Keyword(s):  
Water Management ◽  
Wastewater Treatment ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Biogas Production ◽  
Automatic Frequency ◽  
Municipal Wastewater Treatment ◽  
Organic Micropollutants ◽  
Micropollutant Removal

To achieve the Paris climate protection goals there is an urgent need for action in the energy sector. Innovative concepts in the fields of short-term flexibility, long-term energy storage and energy conversion are required to defossilize all sectors by 2040. Water management is already involved in this field with biogas production and power generation and partly with using flexibility options. However, further steps are possible. Additionally, from a water management perspective, the elimination of organic micropollutants (OMP) is increasingly important. In this feasibility study a concept is presented, reacting to energy surplus and deficits from the energy grid and thus providing the needed long-term storage in combination with the elimination of OMP in municipal wastewater treatment plants (WWTPs). The concept is based on the operation of an electrolyzer, driven by local power production on the plant (photovoltaic (PV), combined heat and power plant (CHP)-units) as well as renewable energy from the grid (to offer system service: automatic frequency restoration reserve (aFRR)), to produce hydrogen and oxygen. Hydrogen is fed into the local gas grid and oxygen used for micropollutant removal via upgrading it to ozone. The feasibility of such a concept was examined for the WWTP in Mainz (Germany). It has been shown that despite partially unfavorable boundary conditions concerning renewable surplus energy in the grid, implementing electrolysis operated with regenerative energy in combination with micropollutant removal using ozonation and activated carbon filter is a reasonable and sustainable option for both, the climate and water protection.

Struvite control through process and facility design as well as operation strategy

2004 ◽  
Vol 49 (2) ◽  
pp. 191-199 ◽  
Author(s):  
J.B. Neethling ◽  
M. Benisch
Keyword(s):  
Wastewater Treatment ◽  
Anaerobic Digestion ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Secondary Treatment ◽  
Operation Strategy ◽  
Municipal Wastewater Treatment ◽  
Facility Design ◽  
Municipal Wastewater Treatment Plants

Struvite deposition is a common problem in municipal wastewater treatment plants and can be signi?cant if not anticipated, but struvite deposits are completely manageable if properly addressed. This paper summarises experiences from a number of facilities that have dealt successfully with struvite problems, elaborates on the interrelations between secondary treatment and anaerobic digestion, and outlines an approach to control struvite and available alternatives.

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