Optimise Anaerobic Digestion with Low Energy Mixing

Anaerobic sludge mixers

Anaerobic digestion is highly dependent upon effective sludge mixing. Ovivo sludge mixers are designed to provide thorough and complete mixing, which maximises solids destruction and as a result, increases gas production.

Ovivo offers several systems, including the innovative LM™ (Linear Motion) Mixer and the EIMIX® Sludge Mixer. Highly efficient, and with low maintenance requirements, these systems can be used with existing and new digesters, and with customised configuration to suit specific tank designs and applications.

Digester mixing plays a key role in maintaining an active digester volume – a critical factor in reliable operations and anaerobic digestion performance. The primary function of the sludge mixing process is to maintain stable digestion by producing uninterrupted contact between the active biology and incoming feed sludge. Upsets to a digester, requiring downtime and maintenance, can be operationally demanding, resulting in significant cost, downtime, and unwanted odour.

Ovivo sludge mixers are designed to provide thorough and complete mixing, through uniform temperature, solids distribution and microorganisms contact with the incoming sludge. Our low energy anaerobic sludge mixers combine proven technology that offers significant cost savings. Our most innovative and popular systems include the LM Mixer and the EIMIX® Sludge Mixer, the features and benefits of which are detailed below.

LM Mixer

Ovivo’s LM Mixer efficiently mixes various municipal sludge types in anaerobic digestion applications, while using significantly less power than conventional mixers. When the tank content is inadequately mixed, stratification occurs and the tank volume is not properly utilised. The LM Mixer achieves a unique and efficient mixing pattern throughout the tank while keeping energy requirements at a fraction of the cost of traditional mixers. Greater than 90 percent active volume mixing is achieved and has been validated through third party LiCl testing for various projects.

Other key features and benefits include:

  • Significant energy savings
  • Complete and thorough mixing
  • Ragless design and low-cost maintenance
  • Lower capital and installation costs than conventional mixers
  • Capable of mixing viscous fats, oils and greases (FOGs)
  • Installation of a single mixer can be completed in a day or less
  • No additional piping or core drilling required
  • Suitable for both new or existing tanks/covers with little to no changes needed on existing structures

EIMIX Sludge Mixer

Ovivo’s Eimix Mixers offer a variety of configuration options, guaranteed to meet any digester mixing requirement. Our mixers use ragless impellers, which are designed to run clean, without the accumulation of stringy or fibrous matter, and to eliminate fouling while retaining high efficiency with low maintenance requirements. The reversible operation enables pumping with equivalent capacity in both directions, maximising system flexibility by altering mixing dynamics.

Other features and benefits include:

  • Stable and highly effective sludge mixing
  • Ragless propellers, designed for improved uptime and long, continuous operating periods
  • Ease of operation and minimal maintenance
  • De-gassing or dewatering the digester for maintenance is not required with our removable mixers
  • Heat exchanger jacket compatibility for uniform heating
  • Internal roof mounted (RDT) or external mounted (EDT) draft tube design
  • Compatible for installation on existing or new, primary or secondary digesters
  • One or more units can be installed across a tank to suit specific mixing needs

LM Mixer

Unlike traditional mixer systems, the LM Mixer is unique in that it produces isotropic (uniform) mixing due to the combined effect of oscillating velocity coupled with pulsating pressure waves. This motion is created by the controlled up and down movement of a ring-shaped hydro-disk (inside the tank) driven by an innovative cam-scotch-yoke operating system (above the tank). This concurrent action couples the oscillating pressure wave and velocity to enhance mass transfer and produce a uniform mixture of the tank’s contents. Plants with a well-mixed digester experience many performance and operational benefits and will achieve a higher degree of volatile solids reduction (VSR) and biogas production. Furthermore, the use of our hydro-disk prevents the build-up of rags and associated failures found in conventional systems.

EIMIX Sludge Mixer

Eimix mechanical sludge mixers utilise axial flow propellers that are symmetrical about both axes and can pump sludge in both directions. The reversible direction of flow (up and down) allows adjustments in the mixing dynamics of the digester. These versatile mixers can be mounted on top of the cover (RDT) or through the side of the digester tank (EDT).