Wastewater treatment plant contaminant profiles affect macroinvertebrate sludge degradation

Meer, Tom V. van der; Verdonschot, P.F.M.; Eck, Lisa van; Narain-Ford, Dominique M.; Kraak, Michiel H.S.

doi:10.1016/j.watres.2022.118863

Cited by 3 publications

(3 citation statements)

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“…Chironomus larvae almost doubled the sludge degradation compared to the control systems, which is in line with previous work on sludge degradation by Chironomus larvae [ 13 ]. Chironomus larvae could enhance sludge degradation even up to five times, when using higher densities of third instar larvae [ 15 ]. Furthermore, uptake of C and N by Chironomus larvae did not explain all C and N removed from the sludge.…”

Section: Discussionmentioning

confidence: 99%

“…The proposed treatment does not require high-tech nor expensive equipment and may therefore be suitable to complement conventional wastewater treatment, especially at locations lacking the infrastructure to apply such high-tech wastewater treatment techniques. Depending on climate, water quality and sludge composition, other species combinations may be more, or less efficient in sludge degradation [ 15 ], assimilation of nutrients or GHG emission reduction [ 17 ]. The processes described here with Chironomus and Azolla may therefore be replicated in other climates using local species.…”

Section: Discussionmentioning

confidence: 99%

“…A similar effect of benthic invertebrate bioturbation on WWTP sludge may be expected, because redox conditions in WWTP sludge are similar to those in organically enriched sediments. Chironomus riparius is a macroinvertebrate with a high sludge degradation capacity [ 15 ] occurring in high densities in organically enriched sediments [ 16 ], which makes it a suitable candidate for the treatment of wastewater. Macrophytes, including floating plants, can effectively remove nutrients from WWTP effluent [ 17 , 18 ], and can affect GHG emissions positively or negatively by altering oxygen concentrations in the water column [ 19 , 20 ].…”

Section: Introductionmentioning

confidence: 99%

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Sludge degradation, nutrient removal and reduction of greenhouse gas emission by a Chironomus-Azolla wastewater treatment cascade

Hendriks,

van der Meer,

Kraak

et al. 2024

PLoS ONE

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Wastewater treatment plants (WWTPs) are a point source of nutrients, emit greenhouse gases (GHGs), and produce large volumes of excess sludge. The use of aquatic organisms may be an alternative to the technical post-treatment of WWTP effluent, as they play an important role in nutrient dynamics and carbon balance in natural ecosystems. The aim of this study was therefore to assess the performance of an experimental wastewater-treatment cascade of bioturbating macroinvertebrates and floating plants in terms of sludge degradation, nutrient removal and lowering GHG emission. To this end, a full-factorial experiment was designed, using a recirculating cascade with a WWTP sludge compartment with or without bioturbating Chironomus riparius larvae, and an effluent container with or without the floating plant Azolla filiculoides, resulting in four treatments. To calculate the nitrogen (N), phosphorus (P) and carbon (C) mass balance of this system, the N, P and C concentrations in the effluent, biomass production, and sludge degradation, as well as the N, P and C content of all compartments in the cascade were measured during the 26-day experiment. The presence of Chironomus led to an increased sludge degradation of 44% compared to 25% in the control, a 1.4 times decreased transport of P from the sludge and a 2.4 times increased transport of N out of the sludge, either into Chironomus biomass or into the water column. Furthermore, Chironomus activity decreased methane emissions by 92%. The presence of Azolla resulted in a 15% lower P concentration in the effluent than in the control treatment, and a CO2 uptake of 1.13 kg ha-1 day-1. These additive effects of Chironomus and Azolla resulted in an almost two times higher sludge degradation, and an almost two times lower P concentration in the effluent. This is the first study that shows that a bio-based cascade can strongly reduce GHG and P emissions simultaneously during the combined polishing of wastewater sludge and effluent, benefitting from the additive effects of the presence of both macrophytes and invertebrates. In addition to the microbial based treatment steps already employed on WWTPs, the integration of higher organisms in the treatment process expands the WWTP based ecosystem and allows for the inclusion of macroinvertebrate and macrophyte mediated processes. Applying macroinvertebrate-plant cascades may therefore be a promising tool to tackle the present and future challenges of WWTPs.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%