Settling Pond Research Articles

Evaluation of Scabiosa ochroleuca L. vitality after introduction on post-flotation wastes1

Abstract The aim of this study was to evaluate the Scabiosa ochroleuca suitability for growth on heavy metals contaminated substrate obtained as a result of Zn–Pb ores exploitation and their processing. Three variants of cultivation were tested in vegetative hall conditions: post-flotation wastes (control), wastes enriched with either mineral fertilisation or with sewage sludge. The possibility of future direct use of the studied species on post-flotation settling pond was determined on the basis of biometric measurements and analysis efficiency of photosynthetic apparatus, that is, pigments content and chlorophyll a fluorescence. The results showed that untreated wastes negatively influenced on plants morphological and physiological status. On the contrary, the application of sewage sludge improved growth and development of cream scabious. Thus, not only the selection of proper plant material, tolerant to toxic levels of heavy metals and other hostile conditions, but also the waste treatment are crucial when metalliferous areas are to be reclaimed.

Nickel, Lead and Zinc Sorption in a Reclaimed Settling Pond Soil

The wastes used to amend soils sometimes have high concentrations of metals such as nickel (Ni), lead (Pb) and zinc (Zn). To determine the capacity of soils to retain these metals, the sorption capacities of different mine soils with and without reclamation treatments (tree vegetation and waste amendment) for Ni, Pb and Zn in individual and competitive situations were evaluated using the batch sorption technique. The untreated settling pond soil had low capacity for Ni, Pb and Zn retention. The site amended with wastes (sewage sludges and paper mill residues) increased the sorption capacity most, probably because of the higher concentrations of soil components with high retention capacity such as carbon and clay fraction. No significant competition was observed between metals in the competitive sorption experiment, indicating that the maximum of sorption was not achieved by adding 0.5 mmol L−1 of metal. We can conclude that, despite the possible additions of Ni, Pb and Zn from wastes to degraded soils, sewage sludges and paper mill residues have a high sorption capacity that would prevent the metals from being in a mobile form.

Assessing the influence of technosol and biochar amendments combined with Brassica juncea L. on the fractionation of Cu, Ni, Pb and Zn in a polluted mine soil

Soil metal pollution is a widespread problem around the world and remediation of these soils is difficult. The objective of this study was to investigate the effect of two different strategies on the chemical fractions of metals in a soil of a depleted copper mine: (1) amending with a mixture of a technosol made of wastes and biochar and (2) amending combined with planting vegetation (Brassica juncea). A 3-month greenhouse experiment was carried out to evaluate the effects of organic amendments and vegetation on the metal fractionation of Cu, Ni, Pb and Zn in a mine soil of the depleted copper mine at Touro (Spain). We compared the influence of organic amendments alone (technosol + biochar) and combined with mustard plants (Brassica juncea L.). The results showed that amending with a technosol made of wastes promoted plant growth (from 0.7 to 2.9 g of biomass produced) and reduced the CaCl2-extractable metal concentration in soil, reduced the mobility factor of Cu from 18.3 to 1.6, Ni from 47.5 to 2.3 and Pb from 17.9 to 2.1, and also reduced the concentration of metals in the mobile soil fractions. It was not possible to grow up Brassica juncea plants in the untreated settling pond soil due to the extremely degraded conditions of that soil. However, the application of the used technosol increased the Pb and Zn pseudototal concentrations in the amended soils. We conclude that the combination of amending with wastes and planting B. juncea provides little additional benefit for remediating a metal-polluted soil compared with incorporation of wastes alone.

THE SETTLEMENT POND AND TRANSBOUNDARY TRANSPORT OF POLLUTANTS BETWEEN DIFFERENT PERTS OF THE CASPIAN SEA

Aim. The settlement pond and transboundary transport of pollutants between different perts of the Caspian sea. Location. Water area of the Caspian Sea. Methods. In the study used the methods of calculating of operational wind fields, sea levels and currents. Results The technology was developed for the calculating of the reservoir and the transport of pollutants between the different parts, with operational hydrodynamic model of high-revolution, located in a mode of “constant readiness”. Mainconclusions. Transport of pollutants characterized by their entry (P) and removal (B) outside for the Russian sector of subsoil, and also of the resulting transfer (RP= P - B– and total transfer (SP= P +B). The different sectors and levels of water were markedly different from each other by the nature of the transfer of pollutants.

English

The listing of the Monongahela River as an impaired waterway prompted the Pennsylvania Department of Environmental Protection (PADEP) to adjust aqueous discharge limits to the river to no more than 250 mg/L of sulfate. In response to this, an analysis of water treatment options for a coal mining company was conducted at several non-operating mines in western Pennsylvania that discharge directly or indirectly to the Monongahela River. Given the extremely high capital and operations costs for typical sulfate reduction methods such as reverse osmosis and ion exchange, novel passive and semi-passive treatment options were explored. An ethanol-fed bioreactor system was selected, designed, and constructed in 2014 to test whether sulfate reducing bacteria could be utilized to remove sulfate in alkaline mine water to meet discharge limits. The unique design elements consist of metals removal circuit, ethanol feed circuit, and twin bioreactors bedded with large cobbles and seeded with sulfate reducing bacteria, but containing no additional carbon source. Biochemical performance has shown that sulfate reduction approaches 1500 mmol SO4 m -3/ day during warmer weather, one of the highest rates recorded in the literature. Effluent sulfate ranged from 58 to 400 mg/L at 16oC and about 1400 mg/L at 2oC compared to influent sulfate concentrations that averaged 2800 mg/L. In addition, the bioreactor produced 500-1500 mg/L of total alkalinity due to microbial metabolism supported by the ethanol, typically corresponding with sulfate decreases. Effluent metal concentrations were decreased to 1 mg/L Fe and 0.2 mg/L Mn. The recirculation loop was found to remove 90% of iron in the original settling pond prior to entering the reactors to minimize sludge accumulation. Additional

Application of Response Surface Methodology in Effective Recovery of Settling Pond Coal Fines by Froth Flotation

In this study, response surface methodology was successfully applied to investigate the operating conditions of the froth flotation process used to recover coking coal fines obtained from a settling pond. A quadratic model was developed to evaluate the variation of yield and the grade of clean-coal product with different test conditions. Thirteen experiments were carried out based on a central composite design technique. The analysis of variance was performed using design expert software to confirm the developed second-order model was statistically significant and adequate to represent the experimental observations. Using this technique, model coefficients, R2, , and F values, were determined to analyze the developed models. Surface plots showing the relationship between the responses, namely, wt % and ash %, with process parameters, and also plots between experimental versus the predicted responses from the models are presented.

Quality assessment indicators of surface waters and soils in the vicinity of the former sulfur mine in the Călimani Mountains

A native sulfur mineralization was quarried out intensively for a period of almost 30 years in Calimani Mountains, the Eastern Carpathians. The waste resulted from this exploitation activity was stored in four waste dumps, while the residues resulted from the processing were disposed in a settlement pond. Although mining operations closed in 1997, the remains of the former sulfur mining are listed among the major pollutants in Romania. The present paper intends to present a preliminary analysis and the current state of the impact of pollution of the former mining exploitation on different environmental factors, by assessing some quality indicators of surface waters and soils. Water and soil samples from different areas situated in the proximity of the former mine were collected and analyzed, performing pH, conductometric, turbidity, chemical and microbiological determinations. The results of this study demonstrate that the pollutant potential of the former sulfur mining from the Calimani Mountains is still very high, a fact proved by the acidic pH of the surface waters and soil, high turbidity and conductivity of the water respectively by the high number of impurities detectable through a simple preliminary chemical analysis.

Changes in the Phytoavailability of Nutrients in Mine Soils after Planting Trees and Amending with Wastes

The purpose of the present study was to evaluate the effect of planting trees (Pinus pinaster or Eucalyptus globulus) and amending with wastes (sewage sludges and paper mill residues) on the nutrient content of mine soils and under field conditions. The studied soils were located in a settling pond and a mine tailing within a former copper mine. The soil samples were analyzed for several physico-chemical characteristics and the concentration of nutrients. The untreated settling pond soil had levels of N and K adequate only for the growth of eucalyptuses and pines, and moreover, the concentration of Ca and P were undetectable. The untreated mine tailing soil presented the same condition, also with adequate levels of Ca and Mg for eucalyptuses and pines. Planting these trees increased the concentration of Mg in the settling pond up to adequate levels only for such trees. Amending with wastes increased the phytoavailable concentration of all nutrients up to adequate levels for most plant species. In conclusion, it is recommended to amend mine soils with wastes rich in nutrients and re-amend after some time because they raise them up to adequate levels for most plants but are depleted over time. It is possible to increase the concentration of all nutrients in mine soils by adding organic wastes, even to values adequate for most plant species.

Phytoremediating a copper mine soil with Brassica juncea L., compost and biochar.

The soils at a depleted copper mine in Touro (Galicia, Spain) are chemically degraded. In order to determine the effect of amendments and vegetation on the chemical characteristics of a mine soil and on the plant uptake of metals, a greenhouse experiment was carried out for 3 months. A settling pond soil was amended with different percentages of a compost and biochar mixture and vegetated with Brassica juncea L. The results showed that the untreated settling pond soil was polluted by Cu. Amendments and planting mustards decreased the pseudototal concentration of this metal, reduced the extreme soil acidity and increased the soil concentrations of C and TN. Both treatments also decreased the CaCl2-extractable Co, Cu and Ni concentrations. However, the amendments increased the pseudototal concentration of Zn in the soil, provided by the compost that was used. The results also showed that mustards extracted Ni efficiently from soils, suggesting that B. juncea L. is a good phytoextractor of Ni in mine soils.

The role of anthropogenic water reservoirs within the landscapes of mining areas – a case study from the western part of the Upper Silesian Coal Basin

Abstract A few thousand anthropogenic water reservoirs can be found in the area of the Upper Silesian Coal Basis (USCB) located in southern Poland. In this paper the role of such anthropogenic lakes in the landscape of the western part of the USCB was presented and illustrated with the example of Knurów, a mining city, and its immediate surrounding area. The study of landscape changes in this area was carried out on the basis of archival and contemporary cartographic materials, historical sources, and interviews with inhabitants and direct field observations. It was found that the origin of the majority of the water reservoirs is related to hard coal, clay and sand mining. They were created primarily as a result of filling subsidence basins and post-mining excavations with water, as well as being the result of the construction of various hydro-technical facilities (settling ponds, fire protection water reservoirs, etc.) In the study area the anthropogenic water reservoirs are of different sizes, shapes and durability and play different roles in the environment. Between 1884 and 2001 their number increased 25-fold, while at the same time their total surface area increased more than 8-fold. The role of the newly created water reservoirs in the landscape primarily involves the transformation of the existing terrestrial ecosystems into wetland ecosystems. The agro-forestry landscape of the late 19th century was transformed into a typically anthropogenic landscape with a dominant share of water reservoirs, settlement ponds and mining waste heaps. The most common species of plants around the water reservoirs are Phragmites australis, Typha latifolia, Ceratophyllum demersum, Elodea canadensis, Potamogeton natans, Lemna sp., Acorus calamus, Myriophyllum verticillatum, Sagittaria sagittifolia, Alisma plantago-aquatica and Glyceria aquatica. The most valuable elements of the flora include Trapa natans and Ruppia maritima, species recognized in Poland as threatened with extinction. Changes in the vegetation cover can be considered favourable since the analysed area is currently characterised by greater biodiversity. Reservoirs are in general positively perceived by residents and used for recreational purposes.

Influence of tubificid worms on nutrient fluxes across water-sediment interface in fish farm settling ponds

Key-words: tubificids, phosphorus, ammonia, nitrate, fish farming, settling ponds The influence of tubificid worms on nutrient translocation from water to fish farm sediments accumulating in settling ponds was addressed under laboratory conditions. Small microcosms of 0.5 L were filled up with 35 g of sludge from a fish farm settling pond and 0.15 L of filtered settling pond water. The experimental set up consisted of one control line (no worms added), a second experimental line with 1 mg of tubificid worms·g −1 fresh sediment (550 individuals·m −2 ) and a third experimental line with 40 mg of tubificid worms·g −1 fresh sediment (22000 individuals·m −2 ). Nutrients translocation was determined by monitoring overlaying water concentration of ammonia, nitrate and phosphate for ten days. Results showed that abundances of 550 individuals·m −2 had no significant influence on the fluxes of nutrients here considered. However, the influence of higher abundances of tubificids (22000 individuals·m −2 ) was of significant extent on the translocation of nitrate and phosphate. Accordingly, bioturbation of tubificids caused 55% lower nitrate uptake by the sediment when compared to control conditions. Phosphorus released by the sediments of the control condition was ca. 90% higher than that recorded under abundances of tubificids (22000 individuals·m −2 ). Results obtained allowed us to estimate that fish farm settling ponds highly colonized by tubificid worms (22000 individuals·m −2 ) may contribute to decrease phosphorus discharge (in terms of soluble phosphorus) in ca. 5go f P·ton −1 of fish produced.

Wastewater treatment for land-based aquaculture: improvements and value-adding alternatives in model systems from Australia

AEI Aquaculture Environment Interactions Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AEI 4:285-300 (2013) - DOI: https://doi.org/10.3354/aei00088 REVIEW Wastewater treatment for land-based aquaculture: improvements and value-adding alternatives in model systems from Australia Sarah A. Castine1,4,*, A. David McKinnon2, Nicholas A. Paul3, Lindsay A. Trott2, Rocky de Nys3 1AIMS@JCU, Australian Institute of Marine Science and School of Marine and Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia 2Australian Institute of Marine Science, Townsville MC, Queensland 4810, Australia 3School of Marine and Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia 4Present address: WorldFish, Jalan Batu Maung, 11960 Bayan Lepas, Penang, Malaysia *Email: s.castine@cgiar.org ABSTRACT: Settlement ponds are used to remove particulate and dissolved nutrients in Australian land-based aquaculture wastewater. At best, marine and brackish water settlement ponds reduce total suspended solids by 60%, but their efficiency is inconsistent. Functional improvements to nutrient removal systems are essential to provide uniform and predictable treatment of flow-through aquaculture wastewater. Furthermore, environmental regulation of discharge from intensive systems in Australia is increasing, providing the impetus to upgrade rudimentary single-step settlement pond systems. We characterise technologies used for land-based aquaculture wastewater treatment prior to discharge from shrimp systems in Australia. We identify opportunities to integrate technologies developed for the treatment of municipal wastewaters and intensive recirculating aquaculture systems, and use these to develop a model system for intensive shrimp farm wastewater. The first stage is the reduction of solids through the use of deep anaerobic ponds, which are tailored to dilute saline wastewater. Non-settled colloidal and supracolloidal solids can subsequently be removed through trapping in a sand bed filter and biological transformation to dissolved inorganic nitrogen or N2. The resulting dissolved nutrients can be treated in a 3-stage algal treatment system by assimilation into harvestable biomass, and finally constructed wetlands polish wastewater through further trapping of particulates, and transformation of dissolved nitrogen. Given that upgrading wastewater treatment facilities is costly, we highlight options that have the potential to offset nutrient treatment costs, such as the use of algal biomass for food or energy products, and the recycling of nitrogen and phosphorus via pyrolysis creating products such as biochar and biofuel. KEY WORDS: Settlement ponds · Crustaceans · Nutrients · Nitrogen · Bioremediation Full text in pdf format Supplementary material PreviousCite this article as: Castine SA, McKinnon AD, Paul NA, Trott LA, de Nys R (2013) Wastewater treatment for land-based aquaculture: improvements and value-adding alternatives in model systems from Australia. Aquacult Environ Interact 4:285-300. https://doi.org/10.3354/aei00088 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AEI Vol. 4, No. 3. Online publication date: December 19, 2013 Print ISSN: 1869-215X; Online ISSN: 1869-7534 Copyright © 2013 Inter-Research.

Microbially enhanced dissolution of HgS in an acid mine drainage system in the California Coast Range

Mercury sulfides (cinnabar and metacinnabar) are the main ores of Hg and are relatively stable under oxic conditions (Ksp = 10⁻⁵⁴ and 10⁻⁵² , respectively). However, until now their stability in the presence of micro-organisms inhabiting acid mine drainage (AMD) systems was unknown. We tested the effects of the AMD microbial community from the inoperative Hg mine at New Idria, CA, present in sediments of an AMD settling pond adjacent to the main waste pile and in a microbial biofilm on the surface of this pond, on the solubility of crystalline HgS. A 16S rRNA gene clone library revealed that the AMD microbial community was dominated by Fe-oxidizing (orders Ferritrophicales and Gallionellas) and S-oxidizing bacteria (Thiomonas sp.), with smaller amounts (≤ 6%) being comprised of the orders Xanthomondales and Rhodospirillales. Though the order Ferritrophicales dominate the 16S rRNA clones (>60%), qPCR results of the microbial community indicate that the Thiomonas sp. represents ~55% of the total micro-organisms in the top 1 cm of the AMD microbial community. Although supersaturated with respect to cinnabar and metacinnabar, microcosms inoculated with the AMD microbial community were capable of releasing significantly more Hg into solution compared to inactivated or abiotic controls. Four different Hg-containing materials were tested for bacterially enhanced HgS dissolution: pure cinnabar, pure metacinnabar, mine tailings, and calcine material (processed ore). In the microcosm with metacinnabar, the presence of the AMD microbial community resulted in an increase of dissolved Hg concentrations up to 500 μg L ⁻¹during the first 30 days of incubation. In abiotic control microcosms, dissolved Hg concentrations did not increase above 100 ng L⁻¹ . When Hg concentrations were below 50 μg L⁻¹ , the Fe-oxidizing bacteria in the AMD microbial community were still capable of oxidizing Fe(II) to Fe(III) in the AMD solution, whereas concentrations above 50 μg L⁻¹ resulted in inhibition of microbial iron oxidation. Our experiments show that the AMD microbial community contributes to the dissolution of mercury sulfide minerals. These findings have major implications for risk assessment and future management of inoperative Hg mines worldwide.

Biocrude production by activated sludge microbial cultures using pulp and paper wastewaters as fermentation substrate

Municipal wastewater activated sludge contains a mixed microbial community, which can be manipulated to produce biocrude, a lipid feedstock for biodiesel production. In this study, the potential of biocrude production by activated sludge microorganisms grown in three different types of pulp and paper mill wastewaters was investigated. A 20% (v/v) activated sludge was inoculated into pulp and paper wastewater, supplemented with glucose (60 g/L) and nutrients (nitrogen and phosphorus) to obtain a high carbon to nitrogen ratio (70:1). The culture was incubated aerobically for seven days. The results showed that the activated sludge microorganisms were able to grow and accumulate lipids when cultivated in amended wastewaters. Microorganisms growing in anaerobic settling pond effluent water showed the highest lipid accumulation of up to 40.6% cell dry weight (CDW) after five days of cultivation compared with pulp wash wastewater (PuWW) (11.7% CDW) and mixed wastewater (MWW) (8.2% CDW) after seven days of cultivation. The lipids mostly contained C16‒C18 fatty acids groups with oleic acid and palmitic acid being the dominant fatty acids. The maximum biodiesel yield was about 6–8% CDW for all the wastewaters. The results showed the potential of utilizing pulp and paper mill effluents and other waste streams, such as activated sludge for the sustainable production of lipids for biofuel production.

Coagulation of Suspended Solids and Neutralization Capacity of Sludge in a Settling Pond of O Limestone Mine

Coagulation of Suspended Solids and Neutralization Capacity of Sludge in a Settling Pond of O Limestone Mine

Algal bioproducts derived from suspended solids in intensive land-based aquaculture

Land-based aquaculture produces suspended solids in culture pond and settlement pond waters that could be harvested as a bioresource. Suspended solids were quantified, characterised and harvested from these two sources to assess their suitability for conversion to bioproducts. The suspended solids of settlement ponds were less concentrated (87.6±24.7mgL−1) than those of culture ponds (131.8±8.8mgL−1), but had a higher concentration of microalgae (27.5±4.0%) and consequently higher particulate organic carbon (24.8±4.7%) and particulate nitrogen (4.0±0.8%). The microalgal community also differed between sources with a higher concentration of fatty acids in the biomass from settlement ponds. Consequently, biochar produced from biomass harvested from settlement ponds was higher in organic carbon and nitrogen, with a lower cation exchange capacity. In conclusion, we characterised a renewable and potentially valuable bioresource for algal bioproducts derived from suspended solids in intensive land-based aquaculture.

Effects of tree vegetation and waste amendments on the fractionation of Cr, Cu, Ni, Pb and Zn in polluted mine soils

Soils at a depleted copper mine in Touro (Galicia, Spain) are physically and chemically degraded and have also polluted the surrounding area. Due to these environmental problems and the large area of these mine soils, the reclamation strategies carried out at Touro have consisted of planting trees (pine or eucalyptus), amending with waste material (sewage sludge and paper mill residues), or using both treatments. Tree planting has been carried out for 21years and waste amending for 10. Two different zones were selected in the mine (the settling pond and mine tailing) in order to evaluate the effect of the different reclamation practices on the chemical fractions of Cr, Cu, Ni, Pb and Zn. The results showed that soils in the untreated sites were polluted by Cr and Cu. Planting pines and eucalyptus on mine soils decreased the concentration of these heavy metals in non-mobile soil fractions. Amendments also attenuated pollution by Cr and Cu as the wastes that were used had lower concentrations than the untreated mine soils. Planting trees increased Ni, Pb and Zn retention in the non-mobile fractions, preventing them from being leached into surrounding areas. However, caution should be exercised when adding organic wastes, as they can lead to increase concentrations of Ni, Pb and Zn and their phytoavailable form. The results also showed that changes in the chemical fractionation of heavy metals in soils was more influenced by the clay percentage and both dissolved and soil organic carbon (SOC and DOC) than by soil pH or cation exchange capacity.

Denitrification and Anammox in Tropical Aquaculture Settlement Ponds: An Isotope Tracer Approach for Evaluating N2 Production

Settlement ponds are used to treat aquaculture discharge water by removing nutrients through physical (settling) and biological (microbial transformation) processes. Nutrient removal through settling has been quantified, however, the occurrence of, and potential for microbial nitrogen (N) removal is largely unknown in these systems. Therefore, isotope tracer techniques were used to measure potential rates of denitrification and anaerobic ammonium oxidation (anammox) in the sediment of settlement ponds in tropical aquaculture systems. Dinitrogen gas (N2) was produced in all ponds, although potential rates were low (0–7.07 nmol N cm−3 h−1) relative to other aquatic systems. Denitrification was the main driver of N2 production, with anammox only detected in two of the four ponds. No correlations were detected between the measured sediment variables (total organic carbon, total nitrogen, iron, manganese, sulphur and phosphorous) and denitrification or anammox. Furthermore, denitrification was not carbon limited as the addition of particulate organic matter (paired t-Test; P = 0.350, n = 3) or methanol (paired t-Test; P = 0.744, n = 3) did not stimulate production of N2. A simple mass balance model showed that only 2.5% of added fixed N was removed in the studied settlement ponds through the denitrification and anammox processes. It is recommended that settlement ponds be used in conjunction with additional technologies (i.e. constructed wetlands or biological reactors) to enhance N2 production and N removal from aquaculture wastewater.

Depletion of Cryptosporidium parvum Oocysts from Contaminated Sewage by Using Freshwater Benthic Pearl Clams (Hyriopsis schlegeli)

The freshwater benthic pearl clam, Hyriopsis schlegeli, was experimentally exposed to Cryptosporidium parvum oocysts, and it was verified that the oocysts were eliminated predominantly via the fecal route, retaining their ability to infect cultured cells (HCT-8). The total fecal oocyst elimination rate was more than 90% within 5 days after exposure to the oocysts. H. schlegeli was able to survive in the final settling pond of a sewage plant for long periods, as confirmed by its pearl production. In the light of these findings, the clam was placed in the final settling pond in a trial to test its long-term efficacy in depleting oocysts contaminating the pond water. The number of clams placed was set to ensure a theoretical oocyst removal rate of around 50%, and the turbidity and the density of feed microbes in the overflow trough water of the pond were about 35% and 40 to 60% lower, respectively, than in the control water throughout the year. It was found that the clam feces containing oocysts were sufficiently heavy for them to settle to the bottom of the pond, despite the upward water flow. From these results, we concluded that efficient depletion of oocysts in the sewage water of small or midscale sewage treatment plants can be achieved by appropriate placement of H. schlegeli clams.

Seasonal growth dynamics and resilience of the green tide alga Cladophora coelothrix in high-nutrient tropical aquaculture

Two distinct climatic seasons in the tropics generate extreme environmental fluctua- tions in land-based aquaculture and corresponding challenges for integrated aquaculture. Here we assessed the influence of environmental and culture variables on productivity of Cladophora coelothrix at multiple scales, firstly in an operational settlement pond and subsequently in labora- tory and flow-through mesocosm experiments. Classification and regression tree (CART) analyses were used to partition the influence of key variables on growth. In situ productivity correlated pri- marily with nitrogen concentration, position in the pond and stocking density, with a lesser influ- ence of salinity, temperature and the ratio of nitrate-nitrogen (NO3 � -N) and total ammonium nitro- gen (TAN). We subsequently evaluated the resilience of C. coelothrix in laboratory and mesocosm environments by manipulating salinity, temperature and nutrients across a broader range of val- ues derived from a year-long survey of the settlement pond. Here temperature had the greatest influence on growth, followed by nitrogen concentration and salinity. Growth rates of C. coelothrix were high, irrespective of season, except at the extremes of each season, for example, at the lowest annual temperature and with the combination of high temperature and low salinity. Growth was also limited by ~20% when NO3 � -N and TAN were available simultaneously. The use of CART analyses for both in situ and controlled environment data provided a formal dissection of the relative contribution of each environmental variable to growth, demonstrating the year-round potential for bioremediation and identifying the critical combinations of environmental variables for management of this system.