Pig Slurry Concentration by Vacuum Evaporation: Influence of Previous Mesophilic Anaerobic Digestion Process

Abstract

Water can be removed from pig slurry by evaporation, through the application of wasted heat from a power plant or from other processes. Apart from obtaining a concentrate with an obviously higher nutrient concentration than the original slurry, another objective of water removal is to obtain water as condensate, which could be reused. The objective of this work was to study the vacuum evaporation of pig slurry liquid fraction and to evaluate condensate composition as a function of both pH (4, 5, and 6) and pig slurry type (fresh slurry and anaerobically digested slurry). Batch experiments showed that condensate characteristics, total ammonia nitrogen (NH 3 -N), volatile fatty acids (VFA), and chemical oxygen demand were strongly dependent on initial slurry pH. In addition to producing part of the required thermal energy, previous anaerobic digestion presented several other clear advantages. The consumption of VFA and other volatile organic compounds during anaerobic digestion reduced the volatilization of organic matter in the evaporation treatment and, consequently, provided a higher quality condensate.

Understanding nitrogen recovery from wastewater with a high nitrogen concentration using microbial electrolysis cells

“…In contrast, the catholyte seems to have some impact on nitrogen recovery, with lower recovery rates obtained when the NaCl solution was used. Ammonia loss through volatilisation might explain the lower recovery rate with NaCl, as the ammonia fraction begins to be significant at pH above 8 (30ºC) [20] ; however, in this study the catholyte pH reached 9 when using NaCl and did not rise above 7.5 when using PBS (Fig. 3).…”

Different approaches to assess the environmental performance of a cow manure biogas plant

“…Even emission values showed high differences among the different approaches used, anaerobic digestion, such as evaporation (Bonmatí et al, 2003;Bonmatí and Flotats, 2003b) or ammonia removal by air stripping (Bonmatí and Flotats, 2003a). Moreover, anaerobic digestion can be integrated with struvite precipitation in order to remove ammonia and phosphates from manure, producing a valuable fertilizer in the meantime (Cerrillo et al, 2015), and also combined with a composting process of the solid fraction of the digestate (Bustamante et al, 2014;Bustamante et al, 2013).…”

Simultaneous removal of NH4+-N and refractory organics through sequential heterogeneous Fenton oxidation process and struvite precipitation: kinetic study

“…The available processes which possess practical importance can be broadly classified into two main categories such as biological processes and physico-chemical processes. [7][8][9][10] The major limitations of these physico-chemical processes are high capital and operating costs and also the fact that the ammonia stripped out from ANWW contribute to air pollution. 4,5 The excess addition of methanol to the system, the pH maintenance and high hydraulic retention time for the treatment of wastewater containing nitrogen were considered to be the major limitations of the biological treatment process.…”