A comprehensive biosolids management solution

DigestivorePAD Process

The DigestivorePAD system reduces the impact of side stream flows that can contain high levels of total nitrogen and ammonia, allowing plants to meet their effluent limits.

DigestivorePAD also provides enhanced volatile solids reduction (VSR) by 10 to 30 percent, which can result in improved dewatering of biosolids and increased capacity.

The DigestivorePAD helps wastewater treatment facilities meet their effluent limits. By providing additional VSR the DigestivorePAD process, they can also reduce their disposal costs significantly. The DigestivorePAD process can be retrofitted into existing sludge storage tanks, which saves in capital and installation project costs. This system also provides O&M cost savings by reducing ammonia in the side stream and stabilising struvite.

A simple biosolids management solution that offers a comprehensive range of benefits

Benefits of the DigestivorePAD process include:

  • Ammonia reduction by approximately 80 percent in the side stream
  • 10 to 30 percent additional VSR
  • Struvite stabilisation
  • Potential improved dewatering
  • Ideal for retrofitting in existing tanks

The DigestivorePAD process consists of anaerobic digestion followed by aerobic digestion step with an internal recycle. By adding an aerobic digestion step after anaerobic digestion additional VSR is accomplished.

Prior studies have shown that during sludge digestion, certain organic compounds can be degraded only under anaerobic or only under aerobic conditions. By combining both in the DigestivorePAD process, we provide an additional mechanism to achieve additional VSR of up to 30 percent compared to that achieved by either anaerobic digestion or anaerobic digestion. The additional organic reduction will also improve the dewaterability of biosolids.

DigestivorePAD has built-in aerobic and anoxic zones, which facilitate nitrification and denitrification processes. This Nit/Denit process results in total nitrogen removal. Since up to 95 percent of the ammonia is removed with aerobic treatment, odours are also reduced significantly.

DigestivorePAD reduces the chance of struvite scaling in process piping and on dewatering equipment. This is achieved by removing ammonium which is a key component required for struvite formation. Furthermore, the post aerobic digestion step (also called PAD) strips CO2 out of sludge and stabilises pH so that any possible struvite formed remains in the sludge (solid phase). This also results in significantly reduced phosphorus levels in the side stream (liquid phase).