Veolia has announced two new processes that improve the efficiency and cost-effectiveness of anaerobic wastewater treatment: Memthane (pictured) and Biobed Advanced, both developed by Biothane, the company’s anaerobic technology center.
Anaerobic technology plays a key role in using wastewater as a resource. It combines the treatment of production effluents with the generation of biogas and the potential for recovering nutrients, thus reducing the environmental impact.
Memthane is an anaerobic membrane bio-reactor (AnMBR), which treats high-strength waste streams found in industries such as distilleries and dairies, previously considered economically untreatable through traditional wastewater processes alone. The company says it can treat streams with convert organic compound (COD) of 15,000 to 250,000 ppm, stillage type streams (pot ale, spent wash, thin stillage and vinasse) as well as fat, oil and grease (FOG) containing streams.
The new Memthane process combines two technologies: Biothane’s anaerobic biological wastewater treatment and Pentair X-Flow’s ultrafiltration (UF) membrane separation process. Influent is fed to the anaerobic bioreactor where the organic components are converted into energy-rich biogas. This clean-energy source allows production plants to be energy self-sufficient, thus reducing the carbon footprint as well as the dependency on costly external fossil fuels.
Next, the anaerobic effluent is processed through the UF membrane unit, separating the “clean” permeate from the biomass. The biomass is returned to the bioreactor, while the ultra-clean filtrate is discharged as particle-free, low biochemical oxygen demand (BOD)/COD effluent.
The company says Memthane has a COD removal efficiency of greater than 98 percent, producing a high-quality effluent that can be discharged directly to the sewer or re-used. The suspended free effluent can also facilitate easy recovery of nutrients for fertilizer production.
Veolia says compared with other technologies Memthane provides a smaller footprint and reduces total operating costs, taking into account all elements, including membranes, chemicals, sludge disposal and overall energy savings.
The second process, Biobed Advanced, is an anaerobic wastewater treatment solution using granular sludge. Veolia says compared to conventional processes, Biobed Advanced reactors provide a more stable performance with a lower footprint.
In traditional wastewater treatment systems using granular-sludge the pre-treated effluent passes a dense and anaerobic granular biomass bed where the COD load present in the wastewater is converted into biogas. In these systems it is all about keeping the biomass in the reactor.
The company says the Biobed Advanced reactor combines the high COD breakdown efficiency and the ease of maintaining and producing anaerobic granular sludge of a conventional upflow anaerobic sludge blanket (UASB) reactor with the cost-effectiveness of a high-loaded system, like the Biobed expanded granular sludge bed (EGSB).
The key element of Biobed Advanced is the design of the settler placed in the reactor top to separate the treated water from the produced biogas and keep the anaerobic biomass in the system, Veolia says. The sludge retaining efficiency of a settler is determined by the available settling area for particles and the reactor turbulence, which is mainly caused by the biogas produced.
In high-rate systems the biogas production is so violent that multi-level gas separation is often used to control the turbulence. But multi-level gas separation reduces the effective reactor volume and thus the performance of the reactor. Veolia says the new Biobed Advanced settler achieves at higher reactor loading rates not only the sludge retention of a UASB system, but also similar COD removal efficiencies.
The company says the compact and standardized settler design reduces the reactor height and investment costs. Compared to other anaerobic systems, Biobed Advanced reactors have a smaller footprint and their performance results in lower operating and post-treatment costs, according to Veolia.
