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.

Benchmarks for the energy demand of nutrient removal plants

2003 ◽  
Vol 47 (12) ◽  
pp. 125-132 ◽  
Author(s):  
O. Nowak
Keyword(s):  
Nutrient Removal ◽  
Energy Demand ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Electrical Energy ◽  
Anaerobic Sludge ◽  
Operational Experience ◽  
Municipal Wastewater Treatment ◽  
Sludge Digestion ◽  
Municipal Wastewater Treatment Plants

The energy demand of municipal wastewater treatment plants for nutrient removal equipped with primary clarifiers, activated sludge system, anaerobic sludge digestion, and CHP is evaluated theoretically, on the basis of COD balances. Operational experience from energy-efficient Austrian treatment plants confirms that the demand on external electrical energy can be kept as low as 5 to 10 kWh/(pe.a) depending on the N:COD ratio in the raw wastewater. A low N:COD ratio helps to keep not only the effluent nitrogen load low, but also the energy demand. Measures to minimise the energy demand at treatment plants and to reduce the nitrogen load are discussed.

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).

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.

Simulation of DEHP biodegradation and sorption during the anaerobic digestion of secondary sludge

2006 ◽  
Vol 54 (4) ◽  
pp. 119-128 ◽  
Author(s):  
M.S. Fountoulakis ◽  
K. Stamatelatou ◽  
D.J. Batstone ◽  
G. Lyberatos
Keyword(s):  
Anaerobic Digestion ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Solid Matrix ◽  
Continuous Stirred Tank Reactor ◽  
Municipal Wastewater Treatment ◽  
Secondary Sludge ◽  
Mass Transfer Processes ◽  
Municipal Wastewater Treatment Plants ◽  
Ethylhexyl Phthalate

Di-ethylhexyl phthalate (DEHP) has commonly been found in the sludge of municipal wastewater treatment plants especially during anaerobic processing. It is slowly biodegradable under anaerobic conditions. Due to its high hydrophobicity, sorption-desorption processes can be rate-limiting for the compound biodegradation. In this study, the anaerobic biodegradation of DEHP was investigated through batch kinetic experiments and dynamic transitions of a continuous stirred tank reactor (CSTR) fed with secondary sludge contaminated with DEHP. A widely accepted model (ADM1) was used to fit the anaerobic digestion of secondary sludge and was properly extended to account for DEHP removal, in which mass transfer processes are also involved. It was shown that DEHP removal was limited by the transfer of DEHP within the solid fraction. The criterion selected for the distinction of the two sites was whether the compound sorbed in those sites was bioavailable for biodegradation or not. Thus, the aqueous phase and the surface of the biosolids were considered as suitable sites for the compound to be bioavailable and the main bulk of the solid matrix was regarded as sites, where the compound remains “protected” against biodegradation. The model, fitted to the batch experimental data, was able to predict DEHP removal in the CSTR operated at various HRTs.

Efficiency of SBR technology in municipal wastewater treatment plants

2002 ◽  
Vol 46 (4-5) ◽  
pp. 293-299 ◽  
Author(s):  
H. Steinmetz ◽  
J. Wiese ◽  
T.G. Schmitt
Keyword(s):  
Wastewater Treatment ◽  
Energy Demand ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Batch Reactor ◽  
Good Alternative ◽  
Municipal Sewage ◽  
Municipal Wastewater Treatment ◽  
Nitrogen And Phosphorus ◽  
Municipal Wastewater Treatment Plants

Four wastewater treatment plants running with sequencing batch reactor (SBR) technology have been evaluated in view of their effluent quality, treatment efficiency and energy demand. The plants are designed for approximately 5,000, 8,000, 15,000 and 25,000 population equivalents (p.e.). Although two of the plants were overloaded during the investigation time the effluent concentrations of nitrogen, especially ammonia, and phosphorus were low. The results show, that SBR plants which are designed according to German standards have additional capacities for degradation of organic matter and removal of nitrogen and phosphorus. Furthermore SBR plants with combined sewer systems are able to treat combined sewage very well. Thus SBR technology proves to be a good alternative for municipal sewage plants and can help to save investment costs.

Removal of hazardous substances in municipal wastewater treatment plants

2020 ◽  
Vol 81 (9) ◽  
pp. 2011-2022
Author(s):  
Vallo Kõrgmaa ◽  
Mailis Laht ◽  
Riin Rebane ◽  
Erki Lember ◽  
Karin Pachel ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Aquatic Environment ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Oxygen Demand ◽  
Hazardous Substances ◽  
Chemical Pollution ◽  
P Value ◽  
Municipal Wastewater Treatment ◽  
Municipal Wastewater Treatment Plants

Abstract Chemical pollution poses a threat to the aquatic environment and to human health. Wastewater treatment plants are the last defensive line between the aquatic environment and emissions of pollutants. This study focuses on identification of most relevant hazardous substances in Estonian municipal wastewater and their fate in the treatment process. During this study, seasonal wastewater and sewage sludge samples were collected from nine municipal wastewater treatment plants and analyzed for 282 hazardous substances, including EU (n = 45) and Estonian (n = 31) priority substances. Results of this study show that several substances that are subject to international restrictions (e.g. Stockholm Convention) are still present in untreated sewage. Wastewater treatment systems that had a greater level of complexity (TEC >5) were more successful in removing hazardous substances. Statistical analyses showed that removal efficiency of organic hazardous substances had significant (p-value <0.05) linear correlation with removal efficiencies of chemical oxygen demand (COD) and total suspended solids (TSS), but a monotonic relationship with operators' competency. This study showed that operators' competency had a strong influence on the stability of the wastewater treatment efficiency and removal of organic hazardous substances.

scholarly journals A STUDY ON RENEWABLE ENERGY SOURCES AND MICROBIAL FUEL CELLS

2016 ◽  
Vol 2 (7) ◽  
Author(s):  
S Venkata Raju ◽  
K Madhusudhana
Keyword(s):  
Organic Matter ◽  
Renewable Energy ◽  
Fuel Cells ◽  
Anaerobic Digestion ◽  
Microbial Fuel Cells ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Renewable Energy Sources ◽  
Municipal Wastewater Treatment ◽  
Municipal Wastewater Treatment Plants

Renewable energy is the energy created by sources, which are naturally replenished such as sunlight, rain, wind and tides. Although there is much debate about how  to define and distinguish renewable energy from non-renewable, other energy types such as biomass, biofuel and anaerobic digestion are also widely considered as renewable energy. Microbial fuel cells(MFCs) that generate electricity by the break-down of organic matter(e.g. wastewater) have a great potential for the future energy and environmental challenges. MFCs are often compared with anaerobic digestion, which also uses microbial activity for breaking down organic matter in the absence of oxygen. Unlike anaerobic digestion, which is relatively well understood and already widely used in municipal wastewater treatment plants, MFCs have received far less attention and funding, hence the technology is still at laboratory level in its development.

Multi-stage constructed wetland systems for municipal wastewater treatment

2013 ◽  
Vol 67 (7) ◽  
pp. 1590-1598 ◽  
Author(s):  
F. Masi ◽  
S. Caffaz ◽  
A. Ghrabi
Keyword(s):  
Wastewater Treatment ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Oxygen Demand ◽  
Average Concentration ◽  
Organic Load ◽  
Municipal Wastewater Treatment ◽  
Multi Stage ◽  
Disinfection Process ◽  
Municipal Wastewater Treatment Plants

In the present paper the detailed design and performances of two municipal wastewater treatment plants, a four-stage constructed wetlands (CW) system located in the city of Dicomano (about 3,500 inhabitants) in Italy, and a three-stage CW system for the village of Chorfech (about 500 inhabitants) in Tunisia, are presented. The obtained results demonstrate that multi-stage CWs provide an excellent secondary treatment for wastewaters with variable operative conditions, reaching also an appropriate effluent quality for reuse. Dicomano CWs have shown good performances, on average 86% of removal for the Organic Load, 60% for Total Nitrogen (TN), 43% for Total Phosphorus (TP), 89% for Total Suspended Solids (TSS) and 76% for Ammonium (NH4+). Even the disinfection process has performed in a very satisfactory way, reaching up to 4–5 logs of reduction of the inlet pathogens concentration, with an Escherichia coli average concentration in the outlet often below 200 UFC/100 mL. The mean overall removal rates of the Chorfech CWs during the monitored period have been, respectively, equal to 97% for TSS and Biochemical Oxygen Demand (BOD5), 95% for Chemical Oxygen Demand (COD), 71% for TN and 82% for TP. The observed removal of E. coli by the CW system was in this case 2.5 log units.

The effect of direct addition of iron(III) on anaerobic digestion efficiency and odor causing compounds

2013 ◽  
Vol 68 (11) ◽  
pp. 2391-2396 ◽  
Author(s):  
Chang Min Park ◽  
John T. Novak
Keyword(s):  
Anaerobic Digestion ◽  
Ferric Chloride ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Positive Impact ◽  
Municipal Wastewater Treatment ◽  
Organic Sulfur Compounds ◽  
Solids Retention ◽  
Municipal Wastewater Treatment Plants ◽  
Iron Addition

The role of iron addition to sewage sludge prior to anaerobic digestion was evaluated to determine the effect of iron on digestion performance and generation of odor-causing compounds. Hydrogen sulfide (H2S) and volatile organic sulfur compounds (VOSCs) were the odorous gases evaluated in this study. Samples were obtained from seven municipal wastewater treatment plants (WWTPs), and batch anaerobic digestion tests were conducted using primary and secondary sludges at 30 day solids retention time (SRT) under mesophilic conditions. Volatile solid removal (VSR) was highly predictable with background iron concentrations measured in the combined sludge. They were likely to increase as influent iron content increased. 1.25% w/w ferric chloride (FeCl3) was added to the anaerobic digester feed in order to simulate iron addition for sulfide control in full-scale WWTPs. The results showed that it had a positive impact on digestion performance with higher VSR and odor control with reduced H2S and TVOSCs in the headspace gas of dewatered biosolids considered in the tests. Ferric chloride is considered a beneficial additive as a strategy for an odor mitigation, not to mention more efficient digestion under anaerobic conditions.

Sign in / Sign up

Export Citation Format

Share Document