Full-Scale Odor Abatement Technologies in Wastewater Treatment Plants (WWTPs): A Review

The release of air pollutants from the operation of wastewater treatment plants (WWTPs) is often a cause of odor annoyance for the people living in the surrounding area. Odors have been indeed recently classified as atmospheric pollutants and are the main cause of complaints to local authorities. In this context, the implementation of effective treatment solutions is of key importance for urban water cycle management. This work presents a critical review of the state of the art of odor treatment technologies (OTTs) applied in full-scale WWTPs to address this issue. An overview of these technologies is given by discussing their strengths and weaknesses. A sensitivity analysis is presented, by considering land requirements, operational parameters and efficiencies, based on data of full-scale applications. The investment and operating costs have been reviewed with reference to the different OTTs. Biofilters and biotrickling filters represent the two most applied technologies for odor abatement at full-scale plants, due to lower costs and high removal efficiencies. An analysis of the odors emitted by the different wastewater treatment units is reported, with the aim of identifying the principal odor sources. Innovative and sustainable technologies are also presented and discussed, evaluating their potential for full-scale applicability.

Elimination of volatile organic compounds by biofiltration: a review

Volatile organic compounds (VOCs) are pollutants that are responsible for the formation of the tropospheric ozone, one of the precursors of smog. VOCs are emitted by various industries including chemical plants, pulp and paper mills, pharmaceuticals, cosmetics, electronics and agri-food industries. Some VOCs cause odor pollution while many of them are harmful to environment and human or animal health. For the removal of VOCs, biofiltration, a biological process, has proved to be reliable when properly operated. This process has therefore been widely applied in Europe and North America. The main advantages associated with the use of biofiltration are related to its set-up, maintenance, and operating costs which are usually lower than those related to other VOCs control technologies and because it is less harmful for the environment than conventional processes like incineration. In the present paper, the main parameters (type, moisture, pH, and temperature of filter bed, microbial population, nutrients concentrations, and VOCs' inlet load) to be controlled during the biofiltration are identified and described in detail. The main phenomena involved in biofiltration are also discussed. For improving the efficiency of VOC control biotechnology, new techniques are now proposed that include the use of membranes, biphasic reactors, UV photolysis, and many others.