Treating more wastewater for less money

Developments and challenges in municipal wastewater treatment

Germany began targeted investments in wastewater treatment plants in the 1970s to respond to growing public pressure and increasing pollution. The Water Management Act (WHG) of 1976 created a binding framework for the first time, requiring industry and municipalities to treat wastewater before discharging it into the environment. From the 1980s onwards, the federal government and states made substantial investments in the expansion and modernization of wastewater infrastructure. The EU Municipal Wastewater Directive of 1991 further strengthened this expansion with its strict requirements. Recently, the EU Council of Ministers approved a revised version of the Municipal Wastewater Directive.

In Germany, wastewater is treated to the highest EU purification standards almost everywhere. Since 1995, the connection rate has increased from 85% to 97% by 2021. During the same period, the number of plants dropped from over 10,000 to just under 9,000. This shows the trend towards centralization and the large number of aging plants. Expiring permits, new water laws, and the outdated infrastructure of wastewater treatment plants create huge challenges for local authorities.

The German water management sector needs to continuously modernize to maintain established standards and comply with new requirements. The high costs of maintaining and upgrading wastewater technology make it hard for local authorities to avoid charging fees.

Conventional solutions

Municipalities often rely on complex construction measures for the upgrading, new construction, or pumping of wastewater. The planning and execution of these conventional construction sites are both time-consuming and expensive. While these methods are familiar, they are no longer the only options available.

Innovative alternatives are rare and often struggle to enter the municipal sector. There are several reasons for this, with rigid processes and conflicts of interest between stakeholders being major factors. As a result, the optimal solution is often overlooked.

The potential for municipal wastewater treatment – ClearFox® Wastewater treatment plants

For almost 20 years, PPU Umwelttechnik GmbH in Upper Franconia has been developing a promising alternative solution for efficient and sustainable municipal wastewater treatment: a cascaded, submerged fixed-bed process installed in standardized ISO sea containers.

These containerized wastewater treatment plants are widely used across various industries, including pharmaceuticals, oil and gas, food production, and domestic wastewater treatment. Today, ClearFox® wastewater treatment plants treat over 35,000 m³ of wastewater every day in over 50 countries around the world.

The plants consistently treat both highly complex and municipal wastewater, as confirmed by an independent test report from PIA GmbH on the fixed bed reactor (FBR). In the report, a 20-foot FBR container demonstrates a certified purification performance of 100 kg COD and 40 kg BOD5 per day.

The ClearFox® fixed-bed reactor is the biological purification module and can be scaled as required and individually integrated into existing plants. PPU Umwelttechnik GmbH specializes in the installation of the submerged fixed-bed process. This process is highly efficient and resistant to load changes due to its large surface area per unit volume, making it “especially suitable for wastewater treatment in rural areas”. This was confirmed by the ATV working report in 1996.

The modular installation and simple design make ClearFox® container systems an ideal solution for municipal wastewater treatment.

PPU Umwelttechnik GmbH either installs new complete systems or integrates containers into existing wastewater treatment plants. With the turnkey delivery of the system, the customer only needs to prepare an appropriate installation area. In some cases, only minimal on-site installation work is required.

Additional cleaning capacity, extra treatment stages such as nutrient and phosphorus removal, or a new complete system can be quickly set up with little time and cost involved. These systems offer great flexibility and are available for lease or with a “lease-to-buy” option. A trial period can be provided upon request.

In addition to versatile and complex industrial projects, PPU Umwelttechnik GmbH also handles municipal projects. From modernizing existing pond, rotating biological contactors, or aeration systems to constructing completely new wastewater treatment plants for 20,000 people. With an in-house laboratory and a team of experienced engineers, each plant is not only designed according to DWA guidelines but also customized to meet specific needs.

Individual purification stages can easily be integrated into an overall system plan, including mechanical pre-treatment, sedimentation tanks, SBR systems, as well as secondary clarification and filtration systems. PPU Umwelttechnik GmbH does not limit itself to container solutions, as concrete plants are also possible.

ClearFox® Case study – The container system upgrades a biodisk system

The existing biodisk system in southern Germany had reached its capacity limit of 800 PE but was still functioning effectively. The municipality initially considered two alternatives. Building a pumping station to transfer wastewater to the next larger treatment plant was very expensive, and the maintenance and operating cost estimates were unconvincing.

Replacing the existing plant also did not make sense to the customer, as the existing plant was still functional.

While searching for other solutions, the municipality came across the ClearFox® container systems. This solution was selected because of its low investment costs and seamless integration with the existing infrastructure.

PPU Umwelttechnik GmbH installed a 20-foot fixed-bed container following the rotary biological reactor. Integrating the container into the treatment process only required a discharge pipe for the pumping station and a basic concrete foundation. This solution allows the existing system to remain in operation. When the old system needs replacing or additional treatment stages are necessary, extra modules can be easily added.

The customer, a municipal organization, wanted to evaluate the solution firsthand and chose a “lease-to-buy” option. After a successful leasing phase, they decided to purchase option earlier than planned. With the ClearFox® fixed-bed reactor, the wastewater treatment plant now has a total capacity of 1500 PE for the required carbon removal.

ClearFox® Case study – Nitrogen removal and phosphorus elimination

The modernization of a pond treatment plant in Hesse is another example of the application of modular technology. The factory was unable to consistently meet the necessary nitrogen limit values of 18 mg/l, even after retrofitting pond aeration. Furthermore, the local authorities required additional phosphorus removal.

After the engineering firm presented various options, the wastewater operator decided to handle it himself. During his research, he came across the modular wastewater treatment systems from PPU Umwelttechnik GmbH. After an inspection, the local authority decided to upgrade the pond treatment plant with two ClearFox® containers: one and a half containers function as fixed-bed reactors, while the remaining half serves as a lamella separator.

The containers were integrated into the existing treatment plant with minimal effort. The customer only needed to build a strip foundation, and only a few piping works were required.

The wastewater is transferred from the existing pump chamber from the first pond to the containers. It passes through the fixed-bed reactor, where denitrification occurs. Part of the denitrified wastewater is returned to the primary clarification via the existing recirculation pipe, while the rest flows through the existing system. The coagulant is dosed directly in the container, and the lamella clarifier efficiently removes the resulting sludge particles.

Overview

The modernization of municipal wastewater treatment is essential to ensure high environmental standards in the long term. With the Clearfox® systems, PPU Umwelttechnik GmbH offers a modern solution that is not only cost-efficient, but also flexible and sustainable. Given the constraints of tight budgets and increasingly stringent environmental regulations, such innovative approaches are essential for safeguarding the environment and alleviating the burden on future generations.

From wastewater to resource