Semi-closed circulation integrated multi-trophic aquaculture treatment system using aquatic organisms as biofilters to improve shrimp effluent quality

Rapid development of aquaculture industry has contributed to the degradation of the coastal environment, and the waterways receiving effluent discharged. The wastewater contains high amount of excess nutrients and total suspended solids (TSS). Shrimp wastewater is rich in excretory waste products because the cultured shrimps could assimilate only 23-31% nitrogen and 10-13% phosphorus of the total inputs. This significantly causes water quality deterioration, outbreaks of shrimp diseases and affect shrimp production. This study focused on biological treatment option using macroalgae to balance the negative impact to the ecosystem. Thereby, Gracilaria edulis and Ulva lactuca were selected and potential as biofilters to improve shrimp water quality has been tested and verified in several laboratory and outdoor tank-scale experiments. Biofiltration potential of macroalgae in outdoor tank shrimp wastewater recirculation system had demonstrated considerably high nutrient removal efficiencies for ammonium, nitrate and phosphate concentrations such as 86%, 53% and 78% for G. edulis and 70%, 42% and 90% for U. lactuca, respectively. Furthermore, semi-closed circulation integrated multitrophic aquaculture treatment system fabricated at outdoor of laboratory with integration of tiger shrimp cultivation and treatment units such as sedimentation tank, green lipped mussel in a spray tank cultivation system and macroalgae tank. Sedimentation tank, reduced TSS, chlorophyll-a, and turbidity by 40%, 22% and 43%, respectively. Mussel system depicted reduction of 65%, 67% and 54.0%, respectively. Whereas, macroalgae had presented remarkable removal efficiencies for ammonium, nitrate and phosphate concentrations by 98%, 79% and 89% for G. edulis and 85%, 63% and 96% for U. lactuca. Besides that, G. edulis had exhibited removal for total nitrogen (TN) by 40%. On the other hand, U. lactuca had shown greater removal for total phosphorus (TP) with 80% removal efficiency, followed by G. edulis by 62.0%. Tissue analysis had demonstrated that the final nitrogen content almost doubled than the initial value in both macroalgae. The final phosphorus content of the tissue in G. edulis has doubled and U. lactuca has shown an increase of about 1.5 times. In addition, the mean growth rate for G. edulis and U. lactuca were about 4.4 % d-1 and 3.7% d-1 respectively. The mean growth rate of shrimp in treatment tank was 1.31 ± 0.76 % d-1, doubled compared to control tank with 100% survival rate. Furthermore, maximum sustainable yield approach revealed the optimum macroalgae biomass for harvest to improve the performance of biofiltration capacity. Thus, G. edulis and U. lactuca are suitable as biofilters and potential applications of these findings include improvement of shrimp water quality to an acceptable level that ultimately enhance shrimp and macroalgae productivity besides produces an ecologically sustainable treatment and integrated system

Tropical seagrass as a Bioindicator of Metal Accumulation

Seven species of tropical seagrass found at seagrass bed located in Johor, Malaysia were analysed for As, Cu and Cd accumulation. The species were identified as Enhalus acoroides, Halophila minor, Halophila spinulosa, Halophila ovalis, Thalassia hemprichii, Halodule uninervis and Cymodocea serrulata. Seagrass plant is rapidly becoming one of the methods to determine the overall health condition of aquatic environment. Each seagrass samples were collected and divided into three parts i.e roots, rhizomes and leaves. Samples were grinded, digested and the correlation between each part was analysed using SPSS version 16. Each part of seagrass tissues have the ability to assimilate metals for example the concentration of As, Cu and Cd in tropical seagrass were in the range of 5-48, 6-60 and 10-69 μg/gDW, respectively. Halophila minor and Halophila ovalis indicates positive correlations to translocate metals (As, Cu and Cd) in plants parts (leaves-rhizomes, rhizomes-roots and roots-leaves). Seagrass can accumulate metals depending on pollution that occur, seasonal variation and internal capabilities to translocate metals. The seagrass species especially Halophila ovalis and Halophila minor can act as bioindicator for metal pollution

Ulva lactuca for nutrients biofiltration in a recirculating shrimp effluent treatment system

An outdoor tank scale shrimp cultivation system was developed with integration of green macroalgae species, Ulva lactuca. Intensive shrimp farming produces large amount of waste nutrients, due to excess uneaten feed and excretion. Prior harvesting, shrimp effluent discharged without proper treatment and alleviates water quality of receiving water bodies. Coastal water degradation consequently causes negative environmental impact. This integrated system with U. lactuca, greatly reduced the nutrient loads and incorporated into its biomass. Phosphate removal was 90%, followed by ammonium and nitrate with removal efficiencies of 70% and 42%, respectively. The mean specific growth rate of U. lactuca was 2.25 ± 0.9 % day-1 and shrimp was 0.76 ± 0.09 % day-1. Shrimp growth rate in control tank was significantly lower compared to the treatment tank (P<0.001) and survival rate declined throughout the experimental period. Integration of U. lactuca significantly enhanced the dissolved oxygen with mean value of 5.49±0.06 mg/L and creates a stable pH values compared to control treatment tank. Thus, U. lactuca is a prominent biofilter with rapid growth rate and greatly reduces the overall environmental impact of aquaculture water degradation and stabilize the culture environment and this study highly recommended utilization of U. lactuca as a biofilter component in an integrated multitrophic aquaculture treatment system

Waste derived biocomposite for simultaneous biosorption of organic matter and nutrients from green straw biorefinery effluent in continuous mode activated sludge systems

The conventional disposal of green straws through burning can be eliminated in a biorefinery that converts them into a range of sustainable commercial products. However, this leads to the generation of green straw biorefinery effluent (GSBE). Green straw biorefineries discharge wastewater into the ecosystem that contains high concentrations of COD and NH4+−N. It is one of the most notable sources of visual pollution and disruption of aquatic life as well as public health that requires treatment prior to discharge. To improve the GSBE quality for environmental sustainability, the attainment of sustainable development goals 6, 9, and 14, "clean water and sanitation", "inorganic and organic waste utilization for added values from material", and "life below water" is very important. Therefore, the effectiveness of the continuous mode activated sludge (CMAS) system and the biocomposite-based–continuous mode activated sludge (SB-CMAS) system in the treatment of GSBE was investigated in this study. Response surface methodology (RSM) was used to optimize the process variables. At their optimized conditions, the performances of CMAS and SB-CMAS were analyzed in terms of COD and NH4+−N. Findings showed 81.21% and 95.50% COD and 78.31% and 87.34% NH4+−N reduction in concentration for CMAS and SB-CMAS, respectively. The high COD and NH4+−N removal efficiencies indicate the better performance of CMAS and SB-CMAS. The first- and second-order models and the modified Stover–Kincannon biokinetic models were utilized to analyze substrate removal rates. It was discovered that the modified Stover models were ideal for the measured data with R2 values 0.99646 and 0.91236 attained for COD and NH4+−N, respectively, in CMAS. The SB-CMAS had 0.99932 and 0.99533 for COD and NH4+−N, respectively. Maximum contaminant elimination was attained at 60% GSBE and 2-day HRT. Thus, to achieve the UN SDGs for 2030, findings from this study have the potential to answer goals 6, 9, and 14

Combined treatment of domestic and pulp and paper industry wastewater in a rice straw embedded activated sludge bioreactor to achieve sustainable development goals

The pulp and paper industry has been recognized as one of the largest users of water worldwide. Water is used in nearly every step of the manufacturing process. It generates significant amounts of wastewater and leftover sludge, creating several problems for wastewater treatment, discharge, and sludge disposal. Adopting the most effective and economical treatment techniques before discharging wastewater is therefore crucial. Thus, this study aims to evaluate the performance of the activated sludge bioreactor system (ASBS) for the treatment of pulp and paper industry wastewater (PPIW). The PPIW was characterized. During the experiment, the domestic and PPIW wastewater were run at a fixed HRT of 1 day. Subsequently, the ASBS was evaluated by varying the HRT and OLR. The HRT was varied in the range of 3, 2, and 1 day. At a fixed HRT of 2 days, the maximum and minimum COD removal were 88.4 and 63.2%. Throughout the study, the ASBS demonstrated higher treatment efficiency in terms of COD removal. First order, Grau second order, and modified Stover Kincannon biokinetic models were applied for the study. The biokinetic investigation shows that the modified stover kinetic model was more appropriate for the description of the experimental data in terms of microbial growth parameters. Thus, the kinetic coefficients obtained in this study could be used for the bioreactor scale-up. The study has also proven that the biosorbent made from biomass waste can potentially help preserve non-renewable resources and promote zero-waste attainment and principles of a circular bioeconomy

Effect of hydraulic retention time on the treatment of pulp and paper industry wastewater by extended aeration activated sludge system

The pulp and paper industry produce dark-colored effluent with high levels of organic matter and nutrients. As a result, a biological treatment system consisting of an aeration tank containing 3.5-6 g/L starting biomass and a clarifier chamber was set up in this investigation. After acclimation, the reactor was driven at a flow rate of 5 L/day for a few weeks at 48h, 24h, and 12h HRT. All through the investigation, the concentrations of organic and nutrient parameters are measured in the influent and effluent samples and documented for data processing. The results reveal that ammonia has satisfactorily met the Standard 'A' standard limits of 10 mg/L after 24 hours of HRT. As a result, reduction efficiencies for nitrate and COD were 80.5% and 95%, respectively. Surprisingly, the majority of the effluent COD readings met the acceptable standard, so no additional testing is required. The mean BOD concentration in effluent was found to be 4.54 mg/L

Boron removal from produce water through adsorption

Boron (B) is essential for the development and functioning of organisms, involving their growth, health, and development of plants, animals, and humans. Nevertheless, the increasing use of boron in various applications has led to environmental problems and health issues. Several separation technologies have been employed to remove boron, and adsorption is one such technology that utilizes adsorbents to address solutions containing extremely low levels of boron. This finding investigates the residual boron from a synthesized solution through adsorption, using CRB05 as the adsorbent. The impact of adsorbent dosage, contact time, boron concentration, and pH on residual boron was examined. The findings indicate that the pH plays a substantial role impact on the residual boron efficiency from all adsorbents. The highest residual of boron was achieved at pH 4.5, adsorbent dosage 1125 mg/L, time 255 minutes, and concentration 1150 mg/L with 98% removal. Adsorption of boron using CRB05 proved to be an effective method for recovering boron from the synthesis solution. The findings of this study enhance our comprehension of the adsorption behavior of CRB05 and provide insights into the optimal operating conditions for efficient boron removal

Approach of maximum sustainable yield (MSY) concept to design a sustainable phytoremediation system to improve shrimp pond water quality

Maximum Sustainable Yield (MSY) concept was applied to investigate about its applicability in order to assess the potential ability of Gracilaria edulis as phytoremediation agent. Strategy to design a high efficiency of sustainable phytoremediation system is addressed in this paper. Tank cultivation of G. edulis was conducted in tank filled with shrimp pond water for six weeks. The active and inactive biomass for vegetative propagation was numerically partitioned and modified logistic model was consisted of active biomass for propagation. It was clearly confirmed the high applicability of modified logistic growth model (R =0.980) when 2 239.2g of biomass was defined as inactive for propagation. According to the result, MSY was 0.68g/day at 12.02g of active biomass under the experimental condition. The simulated logistic model for biomass growth pattern has well employed with the experimental data (R =0.986). According to these results, it is remarkable to 2 consider propagative portion of biomass to assess the behaviour of phytoremediation agent and to consider MSY concept on G. edulis. The results revealed the significance to propose a sustainable phytoremediation system by this approach, which can be focused on the management strategy to retain maximum efficiency of the system. Thereby, it is suggested to consider three parameters, such as, active biomass ratio, intrinsic growth rate and self growth inhibition effect as strategies to design a sustainable phytoremediation system

Inorganic carbon acquisition by Gracilaria edulis and its effect on growth

The utilization of inorganic carbon by the red macroalgae, Gracilaria edulis (G. edulis) was investigated in this study. G. edulis were grown in brackish water aerated with varying concentration of carbon dioxide-350 ppm (actual atmospheric carbon dioxide, CO2), 700 ppm and 1400 ppm CO2 gas. Higher growth rate was observed in culture medium aerated with 1400 ppm CO2 and the lowest growth rate was observed at actual atmospheric carbon concentration. Besides that, significant pH drift was observed in the culture medium with and without enriched carbon dioxide. In the control flask, the pH was higher with a mean of 8.65 ± 0.14, and it greatly differed with carbon dioxide enriched air that exhibited lower pH of a 0.8 unit difference. Photosynthetic rate increased with an increment of inorganic carbon concentration and the highest oxygen evolution were 45µmol g-1FW h-1 and 35µmol g-1FW h-1 at 1400 ppm and 350 ppm, respectively. Therefore, elevated concentration of CO2 significantly decreased the pH of the medium, enhanced growth of macroalgae and evolved more O2