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The microalgae-based activated sludge (MAAS) process was evaluated regarding the removal efficiency of organic matter and nitrogen from physiochemically pretreated municipal wastewater at different hydraulic retention time (HRT) on pilot scale. Additionally, the interplay between the algal and bacterial consortium was evaluated regarding the ability of the algal consortium to provide oxygen for bacterial oxidation processes. The results showed in general high organic matter (COD removal 75-90%) and total nitrogen (40-50%) removal at all HRTs (6, 4 and 2 days). The dissolved oxygen (DO) concentration was maintained stable at 6 days (6.04±0.47 mg L-1) and 4 days (4.24±0.62 mg L-1) HRT. However, the DO significantly declined at 2 days HRT due to loss of biomass at the high influent flow in the sedimentation unit. Nevertheless, the MAAS process functioned as a symbiotic algal-bacterial system with bacterial organic matter oxidation and nitrification and algal nutrient removal.

Entering the papermaking machine, the raw material that goes into a single A4 sheet of paper would look like a bucket of slightly dirty water. In fact, the stock furnished to a paper machine contains over 99 percent water and less than 1 percent actual paper fiber. Although most of the dewatering in papermaking is performed mechanically, a significant amount is done thermally – resulting in colossal energy usage and making paper production one of the most energy-hungry processes in industry. But where such large consumptions are in play, there also exist opportunities for significant savings. This is why ABB offers a paper machine energy fingerprint. This assessment quantifies energy flows and benchmarks energy use in the paper machine, enabling energy-saving opportunities to be identified.

There is a large value in making the Pulp & Paper mills more energy efficient. ABB has developed an energy assessment service where opportunities to save energy in the paper machine are identified. The assessment is done by both quantifying energy flows and benchmarking energy users in the paper machine. After the assessment is done an action plan is presented to the mill of what could be done to improve energy efficiency together with a return on investment.