Nutrient Removal Rates Research Articles

Characterising Recycled Organic and Mineral Materials for Use as Filter Media in Biofiltration Systems

Filter media (FM) sourced from recycled organic and mineral materials offer an effective and low cost means of treating urban stormwater. Using recycled materials rather than the increasingly scarce source of virgin materials (typically sandy loam soil) can ensure a sustainable and long-term economy and environment. This paper presents the results from the laboratory analysis and mathematical modelling to highlight the performance of recycled organic and mineral materials in removing nutrients and metals from stormwater. The analysis included the physical and chemical characterisation of particle size distribution, saturated hydraulic conductivity (Ksat), bulk density, effective cation exchange capacity, and pollutant removal performance. The design mixes (DM), comprising a combination of organic and mineral materials, were characterised and used to develop/derive the modelling design within the Model for Urban Stormwater Improvement Conceptualisation (MUSIC v6). Comparison is made to the Adoption Guidelines for Stormwater Biofiltration Systems—Summary Report which were based on the Facility for Advancing Water Biofiltration (FAWB) guidelines to assist in the development of biofiltration systems, including the planning, design, construction, and operation of those systems. An observed outcome from over two decades of biofiltration guideline development has been the exclusion of alternative biofilter materials due to claims of excessive leaching. Results from this study indicate that high nutrient and metal removal rates can be achieved over a range of hydraulic conductivities using design mixes of recycled organic and mineral materials that have a demonstrated equivalence to existing guideline specifications.

Short- and long-term dynamics of nutrient removal in floating treatment wetlands

Floating treatment wetlands (FTWs) are a plant-based treatment technology shown to remove excess nutrients and metals from surface waters under a variety of conditions. Plants established in FTWs can accumulate and store nutrients within their tissues, but the amount of uptake and storage is dependent on plant species and nutrient influent concentration. This research was designed to quantify the influence of nutrient load and two plant species on nutrient uptake and partitioning patterns within plant tissues (shoots and roots) so that management recommendations for FTWs can be developed to better protect surface water quality. Treatments consisted of (1) two nutrient loads: a high concentration of 15 mg⋅L−1 nitrogen (N) and a low concentration of 5 mg⋅L−1 N supplied as water soluble fertilizer, and (2) four mesocosm treatments: (a) open water, (b) artificial mat only, no plants, (c) artificial mats planted with Pontederia cordata L., and (d) artificial mats planted with Juncus effusus L.. Plant growth, N, and phosphorus (P) uptake of both P. cordata and J. effusus were greater in the high nutrient treatment than in the low. Pontederia cordata facilitated the highest rates of N (0.31 mg.L.day−1) and P (0.34 mg.L.day−1) removal. The nutrient removal rates facilitated by Juncus effusus in the high nutrient treatment were much lower for both N (0.03 mg.L.day−1) and P (0.02 mg.L.day−1). Peak N and P accumulation in J. effusus occurred in September within both root (50 g N and 4.8 g P) and shoot tissues (98 g N and 12.5 g P). The uptake of N and P in P. cordata was highest in root tissues in August (307 g N and 30.5 g P) and in shoot tissues in September (1490 g N and 219.5 g P). In both species, shoots accumulated more N and P than the roots, resulting in a small root:shoot ratio at all stages of the experiment. Harvest of plants from FTWs should occur before plants senesce in the fall, which using P. cordata and J. effusus as model species, occurred from mid- to late-September in USDA Hardiness Zone 8a in the Southeastern United States.

Treating wastewater by indigenous microalgae strain in pilot platform located inside a municipal wastewater treatment plant

ABSTRACT Various resources from a municipal wastewater treatment plant (MWTP) are available for microalgae cultivation plants, suggesting that a combination of these technologies can be used to produce microalgae biomass and remove contaminants at a low cost. In this study, the growth performance and nutrient removal efficiency of an indigenous Scenedesmus sp. in various wastewater media with different exchange patterns were investigated firstly, then transferred to a pilot-scale photobioreactor (located inside a MWTP) for bioremediation use. The temperature and pH of the platform were maintained at 15–30°C and 7.6, respectively. The , , and of the wastewater could be reduced to below 0.05, 0.40, and 0.175 mg L–1, respectively. Our results indicate that microalgae cultivation using the resources of a MWTP can achieve high algal biomass productivity and nutrient removal rate. Our study also suggests that efficient technology for controlling zooplankton needs to be developed.

Polishing the secondary effluent and biomass production by microalgae submerged membrane photo bioreactor

Microalgae are used in wastewater treatment successfully by the uptake of nutrients in secondary effluents that can be used as a valuable biomass. In this study, mixed microalgae culture was used for real wastewater treatment plant (WWTP) for polishing the effluent instead of the specific culture, because the specific culture is contaminated under real environmental conditions. Nutrient removal rates, protein and lipid content of the biomass were determined. Volumetric microalgae productivity was found as 0.037 g/L.day with 3 days of sludge retention times (SRT) and 24 h of hydraulic retention time (HRT) in a 5.5 L microalgae submerged membrane photo bioreactor (msMpBR). Total nitrogen (TN) and phosphate phosphorus (PO4-P) removal rates were found to be 5.55 and 0.40 mg/L.day, respectively, while Navicula sp. and Chaetophora sp. cultures were found to be dominant in steady state. The lipid content was 14.33% and raw protein content was 32.69% in dry biomass. The results showed that N and P can be effectively removed from the real wastewaters by mixed microalgae culture and msMpBR and also algal biomass could be produced with good lipid and protein content.

Comprehensive evaluation of a cost-effective method of culturing Chlorella pyrenoidosa with unsterilized piggery wastewater for biofuel production

BackgroundThe utilization of Chlorella for the dual goals of biofuel production and wastewater nutrient removal is highly attractive. Moreover, this technology combined with flue gas (rich in CO2) cleaning is considered to be an effective way of improving biofuel production. However, the sterilization of wastewater is an energy-consuming step. This study aimed to comprehensively evaluate a cost-effective method of culturing Chlorella pyrenoidosa in unsterilized piggery wastewater for biofuel production by sparging air or simulated flue gas, including algal biomass production, lipid production, nutrient removal rate and the mutual effects between algae and other microbes.ResultsThe average biomass productivity of C. pyrenoidosa reached 0.11 g L−1 day−1/0.15 g L−1 day−1 and the average lipid productivity reached 19.3 mg L−1 day−1/30.0 mg L−1 day−1 when sparging air or simulated flue gas, respectively. This method achieved fairish nutrient removal efficiency with respect to chemical oxygen demand (43.9%/55.1% when sparging air and simulated flue gas, respectively), ammonia (98.7%/100% when sparging air and simulated flue gas, respectively), total nitrogen (38.6%/51.9% when sparging air or simulated flue gas, respectively) and total phosphorus (42.8%/60.5% when sparging air or simulated flue gas, respectively). Culturing C. pyrenoidosa strongly influenced the microbial community in piggery wastewater. In particular, culturing C. pyrenoidosa enriched the abundance of the obligate parasite Vampirovibrionales, which can result in the death of Chlorella.ConclusionThe study provided a comprehensive evaluation of culturing C. pyrenoidosa in unsterilized piggery wastewater for biofuel production. The results indicated that this cost-effective method is feasible but has considerable room for improving. More importantly, this study elucidated the mutual effects between algae and other microbes. In particular, a detrimental effect of the obligate parasite Vampirovibrionales on algal biomass and lipid production was found.

Selective production of volatile fatty acids at different pH in an anaerobic membrane bioreactor

This study investigated the production of major volatile fatty acid (VFA) components in an anaerobic membrane bioreactor (AnMBR) to treat low-strength synthetic wastewater. No selective inhibition was applied for methane production and solvent-extraction method was used for VFA extraction. The results showed acetic and propionic acid were the predominant VFA components at pH 7.0 and 6.0 with concentrations of 1.444 ± 0.051 and 0.516 ± 0.032 mili-mol/l respectively. At pH 12.0 isobutyric acid was the major VFA component with a highest concentration of 0.712 ± 0.008 mili-mol/l. The highest VFA yield was 48.74 ± 1.5 mg VFA/100 mg CODfeed at pH 7.0. At different pH, AnMBR performance was evaluated in terms of COD, nutrient removal and membrane fouling rate. It was observed that the membrane fouled at a faster rate in both acidic and alkaline pH conditions, the slowest rate in membrane fouling was observed at pH 7.0.

Biodiesel production through algal cultivation in urban wastewater using algal floway

The aim of this work was to study algal floway (AFW) to treat urban wastewater and to evaluate biomass productivity, lipid contents and biodiesel production. The results indicated the seasonal average algae productivity of 34.83 g dry weight m2 d−1 with a nutrient removal rate of 2.52 g m2 d−1N and 1.25 g m2 d−1P while the lipid content ranged between 14 and 22% of dry cell weight with the highest lipid productivity of 9.29 g m−2 d−1 during summer. Biodiesel quality was superior during summer with high centane number and cold filter plugging point values. High eicosapentaenoic acid content was found during winter growth cycles. AFW algae community was dominated by pennate diatoms during all growing seasons. This study is one of its kinds in Indian wastewaters and it provides fundamental information for further optimization and use of AFW to treat domestic wastewater and to produce algae biofuel feedstock.

Ecological ditch system for nutrient removal of rural domestic sewage in the hilly area of the central Sichuan Basin, China

Domestic sewage is a key source of surface water pollution in rural areas of developing countries, especially in China, where a large amount of highly concentrated nutrients is directly discharged into the receiving waters. Therefore, in this study, a set of ecological ditch systems was designed to remove nutrients from rural domestic sewage in the hilly area of the central Sichuan Basin, China. The results show that the total nitrogen (TN) removal efficiencies range from 14.87% to 84.24%, with an average of 47.97%, and the total phosphorus (TP) removal efficiencies range from 13.93% to 86.22% with an average of 49.79%. The highest daily TN and TP removal rates are 13.06 and 1.30 g m−2 d−1, respectively, and the average removal rates are 3.19 g m−2 d−1 for TN and 0.28 g m−2 d−1 for TP. Our results indicate that the ecological ditch system to treat rural domestic sewage with high nutrient concentrations can be used in the study area or areas with similar topography. Furthermore, we found that the nutrient removal efficiencies exhibit considerable seasonal variations and are sensitive to the hydraulic flow rates. The nutrient removal capacity of the ecological ditch system is therefore somewhat limited. Based on our findings, the use of winter-hardy wetland plants and increase of the size of the filter unit are recommended to make the ecological ditch system more efficient and maintain high nutrient removal rates year-round. Furthermore, we suggest that regular mowing of plants and the removal of accumulated sediment are necessary to manage the ecological ditch system.

Nitrogen and Phosphorus Phytoextraction by Cattail (Typha spp.) during Wetland-based Phytoremediation of an End-of-Life Municipal Lagoon.

Spreading biosolids on farmland can be an effective and beneficial option for managing end-of-life municipal lagoons. Where the spreading of biosolids on farmland is restricted or unavailable, in situ phytoremediation could be a sustainable alternative. This study examined nitrogen (N) and phosphorus (P) phytoextraction by cattail ( spp.) from biosolids in a wetland constructed within a lagoon cell previously used for primary treatment of municipal wastewater. The effect of harvesting season as well as harvest frequency on N and P removal were evaluated. Forty-eight 4-m plots within the constructed wetland were used to determine the effect of cattail harvest frequency on plant N and P phytoextraction. Harvesting twice per season resulted in a 50 to 60% decrease in phytoextraction of N and P relative to a single harvest per season, which produced biomass yields of 0.58 to 0.6 kg m per year and accumulated 36.7 g N m and 5.6 g P m over the 4-yr period. Compared with August, harvesting cattails in November or April reduced N and P phytoextraction by 63 to 85%. These results demonstrate that phytoextraction of nutrients is more effective with a single harvest compared with two harvests per season. Additionally, we found that while harvesting in November and April is appealing logistically (since the wetland is frozen and provides easier access to harvest equipment), nutrient removal rates are significantly reduced.

Growth promoting ability and enhanced effects on water purification of endophytic bacteria from <i>Canna indica</i>

从美人蕉（Canna indica）植物体内分离内生细菌.通过测定内生细菌产吲哚乙酸（IAA）、铁载体、固氮、溶磷能力筛选出3株内生细菌C01、C16、C20.本试验的目的为评价接种内生细菌能否促进美人蕉种子萌发和幼苗生长，并通过小型浮床水质净化试验，评价接种内生细菌后的美人蕉对水体中营养物质的去除效果.结果表明：C01、C16、C20促进了美人蕉种子的萌发、生长，C16试验组萌发率为83.3%，显著高于对照组31.1%；C16显著提高了植株的株高和根长，分别比对照组高出23.33%、40.44%.水质净化实验阶段，C16试验组总磷、总氮的去除率分别达到88.4%、96.9%，分别比对照组高出26.4%、15.6%.最终，C01、C16试验组生物量、根长都显著高于对照组.C16试验组植株体内可溶性糖含量、可溶性蛋白显著高于对照组317.3%、97.8%.经鉴定，C01为荧光假单胞菌（Pseudomonas fluorescens），C16为肠杆菌（Enterobacter sp.），C20为欧文氏菌（Erwinia sp.）.;Endophytic bacteria were isolated from Canna indica, and three strains C01, C16 and C20 were screened out regard to their abilities of producing indoleacetic acid (IAA) and siderophore, nitrogen fixation, as well as phosphate solubilization. The aim of this study is to evaluate the influence of inoculating of endophytic bacteria on seed germination and seedling growth of C. indica, and to evaluate the removal rates of nutrients in water body by C. indica inoculated with endophytic bacteria in the pilot scale floating bed treatment system. The results showed that C01, C16 and C20 promoted the germination of seed and growth of plants. The germination rate of C16 treatment was 83.3%, significantly higher than that of the control, which was 31.1%. During the water purification experimental stage, the removal rates of total phosphorus and total nitrogen in the C16 treatment were 88.4% and 96.9%, respectively, which were 26.4% and 15.6% higher than the control. At the end of the experiment, the biomass and root length of the C01 and C16 treatment were significantly higher than the control, the soluble sugar content and soluble protein content in the C16 treatment were 317.3% and 97.8% higher than those in the control respectively. C01, C16 and C20 were proved to be Pseudomoanas fluorescens, Enterobacter sp., Erwinia sp. based on 16S rRNA sequence analysis.

Nutrient removal from anaerobic digestion effluents of aquatic macrophytes with the green alga, Chlorella sorokiniana

Green microalgae have great potential for removing inorganic nutrients from wastewater and anaerobic digestion effluent (ADE). We investigated the cultivation conditions for maximum algal yield and nutrient (ammonium and phosphate) removal rates. The green microalga, Chlorella sorokiniana, was cultured using ADE from anaerobic digestion by two dominant macrophytes, Elodea nuttallii and Egeria densa, which cause environmental problems in Lake Biwa, Japan, because of excessive growth. Available magnesium (Mg) in the ADEs from both macrophytes was not sufficient for maximum algal growth and nutrient removal. We demonstrated that Mg-enrichment was essential for enhancing algal yield in, and nutrient removal rate from, ADEs.

Integrated utilization of microalgae cultured in aquaculture wastewater: wastewater treatment and production of valuable fatty acids and tocopherols

Microalgal cultivation in aquaculture wastewater (AWW) from recirculating aquaculture systems (RAS) is an approach for combined production of valuable algal biomass and AWW treatment. The growth, nutrient uptake, fatty acid (FA) profile, and tocopherol content of mixed algal cultures of Euglena gracilis with Selenastrum grown in AWWs from pikeperch (Sander lucioperca) and catfish (Clarias anguillaris) RAS were studied. The highest algal biomass (1.5 g L−1), lipid (84.9 mg L−1), and tocopherol (877.2 μg L−1) yields were achieved in sludge-amended pike perch AWW. Nutrient removal rates in experiments were 98.9–99.5 and 98.4–99.8% for NH4-N and PO4-P, and 75.4–89.2% and 84.3–95.7% for TN and TP, respectively, whereas the COD was reduced by 45.8–67.6%. Biomass EPA and DHA content met, while ARA and tocopherol content exceeded the requirements for fish feed. Algal cultivation in AWWs is a promising alternative for AWW treatment while providing a replacement for fish oil in feed.

Cutting of Phragmites australis as a lake restoration technique: Productivity calculation and nutrient removal in Wuliangsuhai Lake, northern China

Reed is one of the most frequent and dominant species in wetlands all over the world, with common reed ( Phragmites australis (Cav.) Trin. ex Steud.) as the most widely distributed species. In many wetlands, P. australis plays a highly ambivalent role. On the one hand, in many wetlands it purifies wastewater, provides habitat for numerous species, and is a potentially valuable raw material, while on the other hand it is an invasive species which expands aggressively, prevents fishing, blocks ditches and waterways, and builds monospecies stands. This paper uses the eutrophic reed-swamp of Wuliangsuhai Lake in Inner Mongolia, northern China, as a case to present the multiple benefits of regular reed cutting. The reed area and aboveground biomass production are calculated based on field data. Combined with data about water and reed nutrient content, the impact of reed cutting on the lake nutrient budget (N and P) is investigated. Currently, at this lake around 100, 000 tons of reed are harvested in winter annually, removing 16% and 8% of the total nitrogen and phosphorus influx, respectively. Harvesting all available winter reed could increase the nutrient removal rates to 48% and 24%, respectively. We also consider the effects of summer harvesting, in which reed biomass removal could overcompensate for the nutrient influx but could potentially reduce reed regrowth.

Agroindustrial Wastewater Treatment with Simultaneous Biodiesel Production in Attached Growth Systems Using a Mixed Microbial Culture

The use of cyanobacteria in biological wastewater treatment technologies can greatly reduce operation costs by combining wastewater bioremediation and production of lipid suitable as biodiesel feedstock. In this work, an attached growth system was employed to achieve the above-mentioned dual objective using a mixed microbial culture dominated by Leptolyngbya and Limnothrix species in diverse heterotrophic consortia. Kinetic experiments on different initial pollutant concentrations were carried out to determine the ability of the established culture to remove organic load (expressed by d-COD, dissolved-Chemical Oxygen Demand), N and P from agroindustrial wastewaters (dairy, winery and raisin). Biomass and oil productivity were determined. It was found that significant removal rates of nutrients were achieved in all the wastewaters examined, especially in that originated from winery in which the highest d-COD removal rate (up to 97.4%) was observed. The attached microbial biomass produced in winery wastewater contained 23.2% lipid/biomass, wt/wt, which was satisfying. The growth in the dairy wastewater yielded the highest attached biomass productivity (5.03 g m−2 day−1) followed by the mixed effluent of winery-raisin (4.12 g m−2 day−1) and the winery wastewater (3.08 g m−2 day−1). The produced microbial lipids contained high percentages of saturated and mono-unsaturated fatty acids (over 89% in total lipids) in all substrates examined. We conclude that the proposed attached growth photobioreactor system can be considered an effective wastewater treatment system that simultaneously produces microbial lipids suitable as biodiesel feedstock.

Exploring the factors affecting carbon and nutrient concentrations in tree biomass components in natural forests, forest plantations and short rotation forestry

BackgroundCoupling biomass models with nutrient concentrations can provide sound estimations of carbon and nutrient contents, enabling the improvement of carbon and nutrient balance in forest ecosystems. Although nutrient concentrations are often assumed to be constant for some species and specific tree components, at least in mature stands, the concentrations usually vary with age, site index and even with tree density. The main objective of this study was to evaluate the sources of variation in nutrient concentrations in biomass compartments usually removed during harvesting operations, covering a range of species and management conditions: semi-natural forest, conventional forest plantations and short rotation forestry (SRF). Five species (Betula pubescens, Quercus robur, Eucalyptus globulus, Eucalyptus nitens and Populus spp.) and 14 genotypes were considered. A total of 430 trees were sampled in 61 plots to obtain 6 biomass components: leaves, twigs, thin branches, thick branches, bark and wood. Aboveground leafless biomass was pooled together for poplar. The concentrations of C, N, K, P, Ca, Mg, S, Fe, Mn, Cu, Zn and B were measured and the total biomass of each sampled tree and plot were determined. The data were analysed using boosted regression trees and conventional techniques.ResultsThe main sources of variation in nutrient concentrations were biomass component > > genotype (species) ≈ age > tree diameter. The concentrations of Ca, Mg and K were most strongly affected by genotype and age. The concentrations of P, K, Ca, Mg, S and Cu in the wood component decreased with age, whereas C concentrations increased, with a trend to reach 50% in the older trees. In the SRF, interamerican poplar and P. trichocarpa genotypes were comparatively more efficient in terms of Ca and K nutrient assimilation index (NAI) (+ 65–85%) than eucalypts, mainly because leafless biomass can be removed. In the conventional eucalypt plantations (rotation 15 years), debarking the wood at logging (savings of 225% of Ca and 254% of Mg for E. globulus) or the use of selected genotypes (savings of 45% of P and 35% of Ca) will provide wood at a relatively lower nutrient cost. Considering all the E. globulus genotypes together, the management for pulp with removal of debarked wood shows NAI values well above (× 1.7–× 3.9) the ones found for poplar or eucalypt SRF and also higher (× 1.6–× 4.0) than the ones found for oak and birch managed in medium or long rotations. The annual rates of nutrient removal were low in the native broadleaved species but the rates of available soil nutrients removed were high as compared to poplar or eucalypts. Management of native broadleaved species should consider nutrient stability through selection of the biomass compartments removed.ConclusionsThe nutrient assimilation index is higher in poplar grown under short rotation forestry management than in the other systems considered. Nutrient management of fast growing eucalyptus plantations could be improved by selecting efficient genotypes and limiting removal of wood. The values of the nutrient assimilation index are lower in the natural stands of native broadleaved species than in the other systems considered.

Comparison between jet and paddlewheel mixing for the cultivation of microalgae in anaerobic digestate of piggery effluent (ADPE)

There is great need to improve turbulent mixing of microalgae cultures grown in turbid wastewater to ensure efficient use of light and nutrients for higher biomass productivity and nutrient removal rates. In this outdoor study, we compared the turbulent mixing and nutrient removal efficiency of conventional paddlewheel driven raceway ponds (PWP) with customized jet-nozzle raceway pond (JNP) on microalgae grown in undiluted anaerobic digestate of piggery effluent (ADPE). Overall, the concentration of microalgae consisting mainly of Cyanobacteria and Chlorella sp. trended higher in the JNP than the PWP with notable absence of diatoms in JNP. The average percentage of ammonium removal rates were found to be significantly higher in the JNP (36.8% ± 3.93) than the PWP (23.5% ± 4.42). The measured amount of turbulent kinetic energy (TKE), as an indicator of algal movement at eight distinct locations of both ponds, trended higher in the JNP than the PWP, suggesting improved mixing performance with higher shear stress on cultures in the JNP. Based on the higher ammonium removal rates and turbulence mixing, JNP was found to be more efficient for the cultivation of microalgae in ADPE than PWP.

Flow conditions influence nutrient removal at an artificial lake and a drinking water reservoir with an algal floway

To optimize flow condition of algal turf scrubber (ATS) system for nutrient (nitrogen and phosphorus) removal at eutrophic waterbodies, we constructed two experimental scale (2.5 m2) algal floways to test nutrient removal rates under various flow conditions via regulating flow rate and intermittent frequency of pump on/off. Results showed that the largest algal productivity and nutrient removal rate were generally obtained under the hydraulic loadings of 120 L min−1 m−1. Nutrient removal rate was high with an intermittent inflow 4 h−1, followed by 12 h−1 and 60 h−1. We estimated that a hectare-scale floway system under a flow rate of 120 L min−1 m−1 and intermittent flow 4 h−1 which would have satisfactory performance with affordable investment. This option has the greatest potential for the application of such technology in nutrient pollution abatement while producing bioresources from harvested microalgae.

Modelling Nutrients and Organics Removal by Biological Slow Filtration in Micro-Polluted Water Source Treatment

The biological slow filtration (BSF) system as a simple and efficient environmental technology has been widely applied in treatment of ‘micro-polluted’ water. At present, many related studies have focused on the removal efficiency of biological indicators (such as bacteria and viruses). However, there is less research on the removal performance of nutrients and organics in the BSF system. In this paper, we employed a lab-scale biological slow filter to study the removal efficiency and degradation mechanism of nutrients and organics. We proved through adsorption of filter layer at the early running stage and biodegradation at the later stage, the BSF system could achieve effective removal of NH3-N, TN, TP, CODMn and turbidity and the corresponding removal rates are 83.65%, 42.45%, 42.94%, 60.41% and 83.55%, respectively. Furthermore, we also explored the influence of four main factors (filtration rate, filter depth, hydraulic head and temperature) and their interactions on removal rates of nutrients and organics in the BSF system and obtained the optimal operating parameters as follows: filtration rate 0.1 m/h, filter depth 0.8 m, hydraulic head 0.64 m, temperature 26.06 °C. This study would provide a theoretical foundation for the actual application of biological slow filter in treatment of micro-polluted water in developing countries and offer an optimized basis for the design of operating conditions.

Nutrient Dynamics of Different Plants in an Aquaponics Aquaculture System

<div><!--block-->This study evaluates the performance of plants grown at different times in the aquaponics system-a modern and sustainable production method—on water quality. In the established aquaponics system, this study monitored the growth performance of koi fish, Cyprinus carpio var. koi, and different plants (lettuce, Lactuca sativa, var. Crispa as a leafy plant and strawberry, Fragaria sp. as a fruit plant), pertaining to macro nutrient cycling and effects of plants on water quality parameters. Experiments in an aquaponics system comprising a biological filter and plant unit found that the removal rates of macro nutrients from the system were as follows: 1) 4295% for phosphate and 55.45% for nitrate in lettuce and 2) 35.49% for phosphate and 46.36% for nitrate in strawberries. It was observed that, in general, the rate of removing macro nutrients was higher in the lettuce experiment than in the strawberries one. The elimination rates of macro nutrients in this study show that increasing dissolved nutrients in an aquarium is effectively reduced, which confirms that this production system is an environmentally-friendly and sustainable method.</div>

Simultaneous nutrient removal and biomass/lipid production by Chlorella sp. in seafood processing wastewater

Microalgae cultivation in wastewater has received increasing attention in recent years due to its many advantages. In this work, microalgae were cultured in seafood processing wastewater (SPW) for algal biomass and lipid production as well as nutrient removal. The biomass yield of Chlorella sp. achieved in the batch cultivation was 896 mg L−1, indicating that SPW contains a certain amount of nutrients which can be used for the growth of microalgae. However, the maximum specific growth rate of Chlorella sp. cultured in SPW throughout the whole cultivation period was only 0.040 d−1, suggesting that the growth of algal cells was inhibited during the culture process. High concentration of unionized ammonia in the SPW was found to be a factor inhibiting the growth of Chlorella sp. Aerated SPW (ASPW) and diluted SPW (DSPW) proved to be better culture media than SPW without pretreatment. The maximum specific growth rates of Chlorella sp. cultured in ASPW and DSPW during the culture interval were 0.156 and 0.091 d−1, respectively. Aeration pretreatment of SPW reduced the amount of toxic unionized ammonia, while most of the nutrients were retained in the wastewater. Therefore, higher biomass productivity (77.7 mg L−1 d−1) and higher lipid productivity (20.4 mg L−1 d−1) of microalgae were achieved in ASPW. Additionally, improved nutrient removal rates from ASPW were also achieved due to the faster growth of microalgae. The average nutrient removal rates in ASPW during the whole cultivation period were 4.98 and 1.91 mg L−1 d−1 for nitrogen and phosphorus, respectively.