Performance characterization of influent and effluent treatment systems: A case study at Craig Brook National Fish Hatchery

AbstractThis study characterizes the performance of influent and effluent disinfection systems at Craig Brook National Fish Hatchery, a U.S. Fish and Wildlife Service (USFWS) Atlantic salmon Salmo salar restoration facility in East Orland, ME. Influent treatment of the hatchery's water supply limits fish exposure to pathogens and protects the hatchery's goal to recover endangered Atlantic salmon. Disinfection treatment of effluent from the hatchery's wild fish receiving building ensures containment of pathogens that could be transferred to the facility with young fish captured from native rivers and protects the downstream hatchery watershed area. Evaluation of the influent treatment system consisted of assessing the effectiveness of the sand filtration and ultraviolet (UV) disinfection equipment, which are used to treat the water supply for the entire hatchery. Evaluation of the effluent treatment system examined the effectiveness of microscreen filtration and UV equipment that are used to disinfect effluent from the hatchery's wild fish-receiving building. Water samples were collected every 2 weeks for a 6-month period. The evaluation of both treatment systems indicates effective solids removal and total heterotrophic bacteria inactivation (2–4log10 reductions). No disease issues attributable to the hatchery's water supply have occurred during operation of its influent disinfection system, enabling the USFWS continued success with its restoration programs

Bed expansion behavior and sensitivity analysis for super-high-rate anaerobic bioreactor*

Bed expansion behavior and sensitivity analysis for super-high-rate anaerobic bioreactor (SAB) were performed based on bed expansion ratio (E), maximum bed sludge content (V pmax), and maximum bed contact time between sludge and liquid (τ max). Bed expansion behavior models were established under bed unfluidization, fluidization, and transportation states. Under unfluidization state, E was 0, V pmax was 4 867 ml, and τ max was 844–3 800 s. Under fluidization state, E, V pmax, and τ max were 5.28%–255.69%, 1 368–4 559 ml, and 104–732 s, respectively. Under transportation state, washout of granular sludge occurred and destabilized the SAB. During stable running of SAB under fluidization state, E correlated positively with superficial gas and liquid velocities (u g and u l), while V pmax and τ max correlated negatively. For E and V pmax, the sensitivities of u g and u l were close to each other, while for τ max, the sensitivity of u l was greater than that of u g. The prediction from these models was a close match to the experimental data

Processo da retrolavagem em filtros de areia usados na irrigação localizada Backwash process in sand filters used in localized irrigation

O processo da retrolavagem consiste na passagem da água através do filtro em sentido contrário ao fluxo de filtragem com o objetivo de remover partículas orgânicas e inorgânicas retidas no meio filtrante. O projeto de filtros de areia com configurações ineficientes e a ocorrência de condições operacionais inadequadas contribuem para limitar o desempenho desse processo, causando deficiências na limpeza dos meios filtrantes e comprometendo o funcionamento dos sistemas de irrigação localizada. O objetivo do presente trabalho é proporcionar uma revisão sobre os conceitos associados ao processo da retrolavagem nos filtros de areia, relacionando informações existentes na literatura com experiências de laboratório. Foi gerado um texto básico com informações técnico-científicas sobre o tema, visando a criar um momento de reflexão sobre o processo de retrolavagem e a contribuir para a melhoria do desempenho desses equipamentos na irrigação localizada.<br>The backwash process consists of water passing through the filter in the opposite direction of the filtering flow to remove organic and inorganic particles of media filter. Inefficient sand filters designs and the occurrence of inadequate operating conditions contribute to restrict the process performance, causing deficiencies in the filter cleaning and compromise the operation of localized irrigation systems. The objective of this study is to provide a review about concepts associated with the backwash process in sand filters, relating literature information with laboratory experiments. A basic documentation was produced with technical and scientific information on this subject to create a reflection about the backwash process and contribute to the improvement of the equipment performance in the localized irrigation