9 Nov 2020

Efficiency of construction is one of the most important factors in wastewater management projects. The minimum of disruption and time spent onsite during the construction process will be appreciated, not only by the contractors carrying out the work, but by the operators running the plant, and also by the population living in the vicinity of the plant. Time and cost savings in this area are always being explored and implemented. One of the most significant development in this area is the use of Design for Manufacturing and Assembly or DfMA. This is an advanced engineering method that reduces the time spent carrying out onsite construction, whilst also focusing on simplicity of design.

A safer solution

The DfMA method has been applied to the construction of Nereda Package Plants, which provide a small works solution for the wastewater treatment process. By combining these two driving factors – manufacturing and assembly – and streamlining the processes of both, Package Plants can be assembled offsite and then lowered into position, preassembled. Less time spent carrying out onsite construction means less impact on the environment and negative impact on habitats. There are also the additional benefits of reduced dust and noise onsite and reduced construction traffic. Ultimately, DfMA provides certainty of outturn, both to programme and financially.

The Nereda Package Plant is a new way to treat wastewater and a smaller, more compact addition to Royal HaskoningDHV’s successful Nereda wastewater technology product line. Offsite manufacture and construction also mitigates against many health and safety issues onsite – from working at height to confined spaces – with construction operatives kept to the minimum and their time working in potentially hazardous situations reduced. The majority of the construction happens in the factory and the plant is shipped to site and installed on a precast concrete plinth. The time spent onsite in comparison to traditional construction methods is hugely decreased, whilst the speed of installation is increased, and the cost of construction is reduced as a result.

High performance, low cost

Nereda Package Plants have been specifically designed to serve populations of up to 1,600 people. They are ideal for smaller settlements, such as villages, or as an add-on to existing plants, which require periodically increased capacity. They are an attractive option, as they are a factory-built, sustainable solution, which is reflected in their low whole-life cost, enabling a significant reduction in chemical usage required for phosphorus removal. In addition to meeting the stringent current phosphorus removal requirements, Package Plants have also been designed to meet high standards of nitrogen removal. Nereda technology has proven success in achieving treated water ammonia consents down to 1 mg/l and total Nitrogen consents well below 10 mg/l. These elements add up to an attractive ‘package’ for water companies that are looking to address small works wastewater treatment challenges.

The structured approach of ‘design one, build many’ results in lower design costs. It also means safe and efficient manufacture, construction, pre-testing, site assembly and operational start-up. The whole process is much more easily controlled and tracked, and consequently easier to manage. Further savings can be made when water companies commit to a programme of Nereda Package Plants, where each site installs the same treatment plant, allowing for efficiencies in manufacture, operation and maintenance. Package Plants have been designed to be flexible and capable of continuing to achieve consent regulations, even if one of the reactors is taken out of service for maintenance. The plants are also extendable, to meet population growth, or to adhere to tighter future consent standards.

A package that delivers

In addition to their innovative construction, Nereda Package Plants are provided with operational support by MyNereda. This includes the fully-automatic monitoring of performance and optimisation of the plants’ capabilities. Package Plants benefit from having a Nereda Aquasuite controller, a ‘virtual operator’ that never sleeps, which uses learning and optimising software to ensure that the plant automatically adjusts to the wide range of variable operating conditions, temperature changes and wastewater flow and load.

For larger wastewater plant projects of 1,600 to 10,000 population equivalent, Nereda Mini Plants share some of the characteristics with Package, including the DfMA of all MEICA plant and equipment. Due to their larger capacity, prefabricated concrete structures are constructed onsite prior to the MEICA assembly and process start-up.

Nereda Package Plants are an exciting addition to the Nereda family. Essentially, the design and build methods used to construct Nereda Package Plants make them easy, fast, environmentally-friendly and very safe. With the need for increased treatment capacities within stringent water regulation consents, the more cost-savings that can be made at every stage of construction, then the better value that can be realised in delivering improved water service. Sustainable wastewater solutions delivered for small communities through the principles of design one, build many, and DfMA for safe, efficient and optimised water service – enhancing society together.