H2Office

Customer

Engineering association RGBM Schlegel / Dr.-Ing. Steinle

Project name

Dynamic simulation of the WWTP Gut Großlappen (München I)

The problem

The WWTP of Munich I (2 million EP) will be renewed in major areas of the biological stage in the next few years . Currently, the design and detailled engineering is in process.

The WWTP is a two-stage, highly complex plant with bypass and various recirculations. This complexity makes it difficult to use standard calculation methods. On the other hand, this complexity offers a wide range of possibilities to improve the cleaning process and the energy efficiency. A dynamic simulation model was developed to assist in the planning process and to give an outlook on the effect of different operating strategies.

Our solution

The first step was to create and calibrate a model of the existing plant. For the calibration additional measurements were carried out in order to guarantee the highest possible accuracy of the simulation. At the same time, a model for the planned WWTP was developed.

Using the model of the existing plant, the simulation parameters have been calibrated and validated for a period of two years. These parameters have been used further for simulation of the new plant.

Based on that, extreme events and different incidents could be simulated, combined with various control and regulation strategies. Also the plant behaviour during the reconstruction phase was simulated.

More than 20 scenarios have been simulated, showing e.g. the COD, NH4-N and NO3-N concentrations in the effluent as well as energy requirements for pumping and aeration and the gas production.

The results will contribute to the process stability of the planned WWTP. At the same time, recommendations for the ideal operation of the biological stages have been developed, also taking the energy consumption into account.

Furthermore, the dynamic simulation provided more accurate data for the dimensioning and design of different system components, e.g. diffusers and turbo compressors.

Customer

Municipal Utilities Pfaffenhofen a.d.Ilm

Project name

WWTP Pfaffenhofen a.d.Ilm - Renewal CHP plant

The problem

3 older CHP units are currently in use on the KA Oberpfaffenhofen. Due to high operating hours and the new CHP Act a modernization of CHP units had to be assessed. The assessment also included the entire gas line.

Hence, the assessment included also storage, compressing, drying and purification of biogas.

Our solution

In a preliminary study H2Office demonstrated the economic viability of the project.

For this a simulation study was conducted, comparing the measured daily energy production over the last 2 years with the energy production by new more energy efficient CHPs.

The simulation took also into account the existing gas storage, the required amounts of heat and electricity as well as different operating times and capacity utilisation for the CHP units.

Based on this study, the plant operator has decided to renew the CHPS and the gas system. H2Office is responsible for design, detailed engineering and construction supervision.

In meantime the call for tenders for the CHPs, plant construction and electrical engineering are concluded. In November, the first two modules will be put into operation.

Customer

AZV Obere Werntalgemeinden

Project name

WWTP Geldersheim (Bavaria, Germany) - Optimization of operation, energy consumption and energy production

The problem

Since 2006 H2Office has advised the WWTP Geldersheim (50.000 EP) in almost all operational fields. Step by step the effluent quality, energy consumption and energy production should be optimized.

Our solution

Due to temporarily shortages in oxygen supply, the secondary treatment was examined. The necessary adaptation of the aeration system, including the automatic control, was planned and supervised by H2Office. Since then the NH4-N effluent concentrations have been stable and the energy consumption for aeration is very low and on benchmark level.

For the commissioning of the new precipitant dispensing unit for chemical phosphorus removal, a special concept for operation and automatic control was developed.

In 2007 a rough analysis of the energy consumption was conducted together with an economic analysis about co-fermentation with waste greases and food and kitchen waste.

Starting from 2009 until 2011 a full scale test for co-fermentation with the mentioned substrates was performed, resulting in an increase of gas and electricity production of the WWTP Geldersheim by 20 %. At the same time a detailed energy analyses of energy consumption was conducted, based on the previous rough analysis. The implementation of the recommended measures has started 2012 and is on-going.

During the installation of a new process control system the data processing system was adapted to the needs of the operator, according to the specifications of H2Office. The goal was to use the huge pile of measured data more efficiently. This is not only for the control of effluent quality, but also for economical aspects like energy efficiency.

At the beginning of 2011 H2Office performed a cost-benefit analysis concerning the installation of a new CHP. In the same year the planning process started. In spring 2012 the new CHP unit went into operation.

Customer

Siemens Bayern (Bavaria, Germany)

Project name

Energy-check for WWTPs

The problem

A fast and easy to handle tool, to estimate the energy saving potential on municipal WWTPs. The results of the Energy-Check are showing the operator if a more detailed analysis regarding the energy efficiency of the WWTP is recommendable.

Our solution

H2Office has developed a software application for assessing the energy saving potential on WWTPs on basis of their configurations and of the most important operational data. Savings potential in electricity as well as heat consumption of the overall plant and of single areas can be identified.

A package of plausibility control measures guarantees the reliability of the results.

As requested, the Energy Check is designed to be used easily also by non-experts. Since then, more than 40 waste water treatment plants have been analyzed with the E-Check.

Customer

Glass Umwelttechnik

Project name

Energy analysis and energy optimization for the WWTP Bad Wörishofen (Bavaria, Germany)

The problem

H2Office was asked to perform a detailled energy analysis, which would serve as basis for optimizing the energy consumption of the WWTP Bad Wörishofen (43.000 EP). The analysis was conducted on basis of the regulations of a funding program from the local authorities of Bavaria.

Another aim was to assess possibilities of improving the biogas production by introducing co-fermentation.

Our solution

The energy analysis was conducted following the detailed regulations of the funding program in close collaboration with the operator. Missing data were collected during a defined measuring period.

Different aspects, which influence effluent concentrations as well as operation costs, have been evaluated in respect to energy consumption as well as process efficiency. Thereby a significant energy savings potential could be determined, without deteriorating the effluent quality.

Furthermore a cost-benefit analysis was carried out regarding the modernization of the CHP units including the possibility of providing surplus heat to a district heating system.

Customer

Stadtwerke Rottweil

Project name

WWTP Rottweil - Optimization of aeration system and operation strategy (Baden-Würtemberg, Germany)

The problem

At the beginning the primary focus for the WWTP Rottweil (50.000 EP) was on the improvement of nitrification and nitrogen removal. This was especially because of difficulties to keep the nitrogen concentration in the effluent below the legal binding values. The conditions for an optimization of the nitrogen removal looked promising due to a big anoxic volume in the activated sludge tank. However there needed to be a check to see whether the existing aeration system was suitable for implementing optimized control strategies.

Besides of the operational optimization, H2Office attempted to optimize the energy efficiency of the plant at the same time.

Our solution

In a first step a dynamic simulation of the plant was conducted. Therefore the measured influent loads were checked with mass flow balances and compared with results based on estimated values for population and industry connected with the plant.

The calibrated model served to develop different optimization measures, to show their effects in detail and to select the best strategies for short, middle as well as long term application.

In the second stage the selected strategies have been realized. The most important modification was to combine the pre-denitrification with simultaneous nitrification-denitrification. To do so, the aeration system including the control and regulation strategies had to be renewed beforehand. H2Office was responsible for planning and supervision of implementation.

Customer

Research project - financially supported by the City of Vienna

Project name

MODECO – Cost-benefit analyses and Simulation of Co-Fermentation on WWTPs (Austria)

The problem

An average WWTP, possessing anaerobic sludge treatment (fermentation), normally produces electricity in a percentage between 40 and 75 % of its own electric energy consumption. Co-fermentation with regionally available bio waste is able to improve the biogas production significantly. Including co-fermentation in its system, a WWTP can produce up to 100 % of its own electricity production or even exceed its own electricity needs.

The project was part of and funded by of the framework "Vienna Environmental 2008". The aim of the project was to analyse and assess WWTPs with mass flow balances already using co-fermentation regarding their treatment performance as well as economic performance in a first step. Subsequently a simulation model for co-fermentation was developed, which included the definition of general valid parameter values.

The big advantages of simulations are to gain a deeper knowledge about the occurring processes and the possibility to estimate and forecast the resulting gas production and its composition (CH4, H2S). With this results, design and operation strategies can be improved concerning process stability, energy production and economic efficiency.

Our solution

The 3 year long project was a cooperation between H2Office and the institute for water quality, resource and waste management of the technical university of Vienna.

In a first stage, 5 municipal WWTPs which had already implemented co-fermentation, have been investigated. Periods with and without co-fermentation have been examined.

In the next step, a simulation model was developed and tested on 3 of the 5 WWTPs. In the last stage, the WWTP with the best dataset (including waste water and sludge treatment) was simulated for a period of 2 years.

A newly developed technique now helps to characterize the substrate based only on analysing techniques, which are common in wastewater treatment.

The H2S content of the gas, calculated by the model, can be especially important. Excessive H2S content in biogas can lead to fatal problems for the CHPs, in the worst case ending with a total breakdown. Therefore gas desulphurising systems can be designed on the basis of the model results.

"MODECO" is an efficient simulation tool to optimize co-fermentation facilities regarding process stability, energy production and economic output for already operating systems as well as in the design process. Furthermore the tool helps to improve the overall energy management and efficiency of a WWTP as well as to improve its combined heat power plants (CHPs).

Customer

Abwasserverband Oberes Schwarzatal

Project name

Design competition for the extension of the WWTP Stuppach (Lower Austria, Austria)

The problem

According to the Austrian law an EU-wide design competition had to be conducted to select the general contractor.

Therefore the requirements and information regarding legal, technical and environmental issues had to be prepared.

Our solution

H2Office advised the preparation of the design competition in all issues regarding the treatment processes. This involved the preparation of all necessary data for the planning process, the participation in the preparation of the documents for the design competition (including the development of an evaluation system for the offers), checking of references, the economic and technical pre-evaluation of the offers and consulting the jury.

Customer

Wasserverband Ossiacher See (Carinthia, Austria)

Project name

Extension of the WWTP Feldkirchen

The problem

For the extension of the WWTP Feldkirchen to 50.000 PE extremely strict limit values for the effluent concentrations had been set by the local authorities. According to conventional design rules (ATV A 131) a significant enlargement of the volume of the active sludge tanks would have been necessary for achieving these limit values. A previously developed concept, which was based on better utilizing existing tanks and optimizing the operation strategies, became unacceptable.

Our solution

A dynamic simulation was developed and calibrated. Different extension concepts for the WWTP were validated and partly optimized in this simulation model. In this way, an economical concept of enlargement was found. Furthermore the authorities could be convinced, that the effluent concentrations will be below the stringent limit values.

After the commissioning of the new plant, the model was used to optimize the operating and control strategy for the biological stage, considering both process stability and energy efficiency.

Customer

City of Villach (Carinthia, Austria)

Project name

Optimization of the WWTP Villach

The problem

The WWTP (200.000 PE) was suffering from a high sludge volume index for years, which led to a high costs for precipitating agents. One main reason for that was the high percentage of industrial waste water in the influent.

A further aim was to reduce energy consumption and therefore the energy costs of the biological stage.

Our solution

Step 1: Changing the aeration strategy

The sludge volume index could be reduced significantly and long term by changing the aeration strategy in the activated sludge tanks.

Step 2: Optimization of precipitants

In a second step different precipitants have been tested, based on a Europe-wide tendering procedure. Furthermore the location of the precipitant addition, of the control strategy and of the costs of the precipitant itself have been optimized

As a result the costs for the precipitants reduced notably and the sludge volume index could be stabilized under 100 ml/g. Furthermore the nitrogen removal could also be improved.

Step 3: Dynamic simulation in order to optimize the energy consumption

H2Office developed a simulation model for the secondary treatment which was calibrated with measurements on the WWTP. A simulation carried out for time period of 1.5 years showed the effects on the effluent and the energy consumption for the optimized aeration and operation strategy in comparison to the former applied strategy.

Other projects

Abfallwirtschaftverband Kitzbühel (Tyrol, Austria) - Study about co-Fermentation of organic-waste in WWTPs

Economic analysis about a treatment plant for organic waste, in order to prepare organic waste and food waste to be later used for co-fermentation in the WWTPs located in the district of Kitzbühel.

WWTP Karlstadt (Bavaria, Germany) - Invitation for tender for CHP

Preparation of documentation for the invitation for tender and advice for the awarding of contract (in cooperation with SPIEGLtec)

Sewage sludge composting or humification

Economic and technical analysis for Wasserverband Ossiacher See, Unteres Drautal and Wörthersee West about 2 different types of sewage sludge disposal: composting and humification (in cooperation with Hydrologischen Untersuchungsstelle Salzburg)

WWTP Trumerseen - 40.000 EP (Salzburg, Austria) - New aeration control system

Development of a concept and requirement documentation for an optimized oxygen- and blower control and regulation system, including support during the implementation.

WWTP Karlstadt - 30.000 EP (Bavaria, Germany) - Utilisation of biogas

Economic analysis about the production of electricity with CHP or micro gas turbine on the WWTP considering co-fermentation

WWTP Villach 200.000 EP (Carinthia, Austria) - indirect dischargers cadastre

Estimation of COD-, N and P- loads for 255 indirect dischargers, examination of the most important indirect dischargers, preparation of PE-statistics

WWTP Zellingen - 30.000 EP (Bavaria, Germany) - Anaerobic sludge digestion

Economic analysis about the switch from aerobic to anaerobic sludge digestion including utilisation of the produced biogas and concerning co-fermentation as well as humification

WWTP Feldkirchen 50.000 EP (Carinthia, Austria) - Treatment of combined wastewater in secondary settlement tanks

Development of a control and regulation system for the treatment of combined wastewater from storm water tanks in secondary settlement tanks

WWTP Bad Mergentheim 50.000 EP (Baden-Württemberg) - Dynamic Simulation

Examination on the treatment performance and the energy efficiency of the intermittent aeration with a dynamic simulation (on behalf of Messner Umwelttechnik)

WWTP Villach - 200.000 EP (Carinthia, Austria) - Invitation for tender and examination of a possible use of precipitants

Preparation and execution of a multilevel, EU-wide award procedure for precipitants including the support and evaluation of trial runs for the precipitants, as part of the award procedure

WWTP Wolkersdorf - 35.000 EP (Lower Austria, Austria) - Expert opinion on an invitation for tender

Advise on technical issues during a lawsuit concerning the invitation for tender and awarding process

WWTP Villach - 200.000 EP (Carinthia, Austria) - Modernization of the automation infrastructure

Modernization of the control and regulation system (design, invitation for tender, site supervision) in cooperation with SAG-engineers

Commercial WWTP Fischer Entsorgung- und Transport GmbH (Lower Austria, Austria)

Assessment of the biological degradability of physical and chemical pre-treated wastewaters, concerning the possible installation of a biological stage