Bulk decay in TOXIC module

Dear EFDC users,Good day!I’m currently using the TOXIC module in EFEC_Exploler8.4, and have a question of bulk decay. I would like to know the clear definition of bulk decay. Is it different to hydrolysis? If it is, how can model consider the loss of chemicals due to hydrolysis? Additionally, where do you usually find the data (e.g., diffusion rates, particle mixing, and water column decay rate) for running TOXIC modules? It’s difficult for me to find the information, especially diffusion rates and bed surface particle mixing. Thank you ! Sincerely,Minjeong

Hi Minjeong,The best place to look for this documentation is in our knowledge base: https://dynamicsolutions-intl.atlassian.net/wiki/spaces/ETG/overviewHere are the specific sections relevant to your question:https://dynamicsolutions-intl.atlassian.net/wiki/spaces/ETG/pages/101908496/6.3.1+Bulk+Degradationhttps://dynamicsolutions-intl.atlassian.net/wiki/spaces/ETG/pages/101908510/6.3.2+Biodegradationhttps://dynamicsolutions-intl.atlassian.net/wiki/spaces/ETG/pages/101908518/6.3.3+VolatilizationLet me know if that information answers your question or not.Thank you,Tom

Dear Tom, Hi Tom, thanks for your replying. I have checked links you provided but it’s not exactly relevant to my question. The first link mentions that EFDC considers the first order decay, called bulk density. My questions are: What is a definition of bulk density? Does it mean or include hydrolysis? Otherwise, EFDC doesn’t consider hydrolysis? In case that hydrolysis is experimentally second order reaction, how can it be considered in EFDC? Additionally, I would like to ask where you usually find the references for diffusion rates and bed surface particle mixing parameters. Thank you very much. Sincerely,Minjeong

Hi Minjeong,Sorry those articles did not answer your original question.Regarding the process of hydrolysis specifically, you would need pH in order to simulate those reactions, is that correct? I can say that at this stage, EFDC+ is not capable of simulating pH but that is something we are working towards.Tom