Application of experimental design method for advanced treatment of dairy wastewater by ozonation

In this study, application of experimental design method for ozonation of dairy wastewater was investigated. The Taguchi systematic method was used in the planning stage of experimental approach. The experimental design was applied using L-9 orthogonal array with three factors and three levels. The optimum experiment conditions were determined for pH, temperature and ozone contact time for ozonation process. Analysis of variance (ANOVA) analyses based on the Taguchi approach was performed both for statistical evaluation of the results and determination of the influence and relative importance of the factors on removal efficiencies. The optimal experimental condition for DFZ(436) parameter was determined as 10 for pH, 25 degrees C for temperature and 15 min for ozone contact time. Relative importance of experimental factors on DFZ(436) removal performance is evaluated by ANOVA analysis, and the order of the factors was determined as; ozone contact time > pH >> temperature. According to the confirmation experiment conducted under the optimum conditions, removal efficiency for DFZ(436) was determined as 88%, which was close to the predicted value of 85%. (c) 2018 American Institute of Chemical Engineers Environ Prog, 38:e13025, 201

Does trait‐based joint species distribution modelling reveal the signature of competition in stream macroinvertebrate communities?

1. The occupancy and abundance of species are jointly driven by local factors, such as environmental characteristics and biotic interactions, and regional‐scale factors, such as dispersal and climate. Recently, it has been shown that biotic interactions shape species occupancies and abundances beyond local extents. However, for small ectothermic animals, particularly for those occurring in freshwater environments, the importance of biotic interactions remains understudied. Species‐to‐species associations from joint species distribution models (i.e. species associations while controlling for environmental characteristics) are increasingly used to draw hypotheses of which species possibly show biotic interactions. 2. We studied whether species‐to‐species associations from joint species distribution models show signs of competition using a hypothesis testing framework in stream macroinvertebrate communities at regional extent. 3. We sampled aquatic macroinvertebrates from 105 stream sites in western Finland encompassing a latitudinal gradient of ca. 500 kilometers. We hypothesized that if competition drives these associations (H1) functionally similar species are mostly negatively associated, whereas functionally dissimilar species show random associations. We further hypothesized that the relationship between functional dissimilarity and the strength of association is more pronounced (H2) for abundances rather than occupancies, (H3) at small grain (i.e. stream site) rather than at large grain (i.e. river basin), and (H4) among species having weak dispersal ability than among species with high dispersal ability. 4. Stream macroinvertebrates showed both negative and positive species‐to‐species associations while controlling for habitat characteristics. However, the negative associations were mostly at large grain (river basin) rather than at small grain (stream site), in occupancy rather than abundance, and not related to species functional dissimilarity or to their dispersal ability. Thus, all our hypotheses considering possible competition (H1‐H4) were rejected. 5. Competition does not appear to be a major driving force of stream macroinvertebrate communities at the spatial grain sizes considered. The observed positive associations in occupancy at small grain (stream site) may be attributed to species’ similar microhabitat preferences, whereas at large grain (river basin), they may stem from metacommunity dynamics. Our results highlight that species traits were necessary to interpret whether or not species‐to‐species associations from joint species distribution models resulted from biotic interactions.peerReviewe

Pollutant footprint analysis for wastewater management in textile dye houses processing different fabrics

BACKGROUND: This study investigated the water and pollution footprints of a dye house, which processed cotton knits, polyester (PES) knits and PES-viscose woven fabrics. Experimental evaluation was carried out for each processing sequence. Variations in wastewater flow and quality were established as a function of the production program in the plant. A model evaluation of wastewater dynamics was performed and defined specifications of an appropriate treatment scheme. RESULTS: The plant was operated with a capacity of 4300 t year−1 of fabric, which generated a wastewater flow of 403 500m3 year−1 and a COD load of 675 t year−1. The overall wastewater footprint of the plant was computed as 91m3 t−1 and the COD footprint as 160 kg t−1 of fabric. Depending on the fabric type, results indicated expected changes in wastewater flow between 600 and 1750m3 day−1 in COD load between 1470 and 2260 kg day−1 and in COD concentration between 1290 and 3400mgL−1. CONCLUSION: A model simulation structured upon COD fractionation and related process kinetics revealed partial removal of slowly biodegradable COD, coupled with high residual COD, which would by-pass treatment. Resulting biodegradation characteristics necessitated an extended aeration system, which could also enable partial breakdown of residual COD. Effluent COD could be reduced to 220–320mgL−1 with this wastewater management strategy. © 2018 Society of Chemical Industr