A Solution for Sustainable Utilization of Aquaculture Waste: A Comprehensive Review of Biofloc Technology and Aquamimicry

Biofloc technology (BFT) is gaining traction as a strategic aquaculture tool for boosting feed conversions, biosecurity, and wastewater recycling. The significant aspect of BFT is aquaculture with highest stocking density and minimal water exchange. It not only improves the water quality of a system by removing inorganic nitrogen from wastewater but also serves as a suitable feed supplement and probiotic source for cultured species. This technology is commonly used for shrimp and tilapia culture and can be used for both semi-intensive and intensive culture systems. Biofloc, when combined with formulated diets, forms a balanced food chain that improves growth performance. Nutrients in this system are continuously recycled and reused and form an efficient alternative system in aquaculture. In addition to the reduction in water exchange, it is also considered as a bio-security measure, since it prevents entry of disease from outside sources. Aquamimicry is an innovative concept that simulates natural estuarine conditions by developing copepods that act as supplementary nutrition especially for shrimp culture. The review highlights the process, significance, and development of BFT, its microbial interactions, nutritional value, transition from biofloc to copefloc, and concept of aquamimicry to sustainably improve aquaculture production.

Sinkhole Flooding and Aquifer Recharge in Arid to Dry Sub-Humid Regions: A Systematic Review

Sinkhole flooding is an essential hydrological process to recharge karst aquifer in arid to dry sub-humid regions. On the other hand, the increase of rain extremes is one of the major consequences of the global warming, together with the expansion of drylands. Thus, appropriate runoff regulation in endorheic karst basins in order to reduce the risk of flooding and improve the quantity and quality of the water drained by sinkholes will be more and more crucial. With these premises, a systematic review was performed by using WoS engine to infer the best practices for the karst water management in regions actually or potentially affected by water scarcity. Hydrological models are essential to manage the consequences of climate change on karst water resource, however the review shows that providing the tools necessary for reliable modeling is still challenging. Finally, due to the intrinsic vulnerability of the karst aquifers, pollution reduction and wastewater recycling policy will play key role in the next decades.

Advances in Microfiltration and Ultrafiltration Technology for Greywater Treatment: A Review

Advances in microfiltration and ultrafiltration technology for the treatment of greywater are important today because everything surrounding the use and preservation of water is an issue that increases in importance over the decades, and our planet will be seriously affected by the consequences of climate change, making water availability uncertain. Hence, wastewater recycling and its cyclical use have become a major topic in the scientific and engineering communities. The objective of this research is focused on compiling and updating all the advances in wastewater treatment, with emphasis on Greywater, in which components have a lower pollutant load than the rest of wastewater. In addition, microfiltration and ultrafiltration technologies were the technology selected to investigate in this investigation because they have the local potential for a second use of the wastewater before the discharge of contaminated water to the sanitation network. This research was carried out using words related to the exposed topic, such as “microfiltration”, “ultrafiltration”, “cleaning wastewater” and “greywater” in the search for documents in scientific search engines, selecting those that covered the topic and could be used to create this document. The results that were developed in this investigation, indicate that there is no generalized consensus on how to treat this greywater, nor how to qualify it. Additionally, it is important to note that despite the fact that urban greywater treatments have given good results, with the widespread use of bioreactors for this task, and the existence of various treatment alternatives for liquid waste that have shown good price-value ratio, studies related to greywater treatments using porosities are still in the incipient stages.

Application of Nano Bio-clay Composite in a Scaling-up Study for Wastewater Treatment

A scaling-up study integrating experimental and field experiments was managed to explore the most appropriate catalysis method to assist industries in getting rid of the Congo Red (CR) dye from industrial wastewater. The adsorption potential of kaolinite (K) modified by Ulva Lactuca (UL) was evaluated to eliminate CR dye from aqueous solutions. The novel kaolinite/alga nanocomposite (KUL) was synthesized following steps of the wet impregnation method and then subjected to characterization using different techniques. The newly reported KUL nanocomposite shows a significant increase in adsorption ability higher than that of K and UL. To research different experimental factors' effects, batch experiments were evaluated, and each of the kinetics/isotherms of CR adsorption were explored either. The CR removal% is clearly affected by catalyst dose, working temperature, and pH value with high percentage. The best temperature for CR adsorption onto KUL is 400C at pH>7. CR adsorption on KUL following the first-order diffusion model, while K and UL appeared to follow two different kinetic adsorption models depending on the CR concentration. Moreover, the field tests (scaling-up experiments) revealed optimistic results with 91% efficiency for KUL nano-adsorbents in eliminating mixed dyes from industrial wastewater, which means the foundation of novel environmentally benign nano-adsorbents to help in industrial wastewater recycling.

Colorimetric determination of urea using diacetyl monoxime with strong acids

Urea is a byproduct of the urea cycle in metabolism and is excreted through urine and sweat. Ammonia, which is toxic at low levels, is converted to the safe storage form of urea, which represents the largest efflux of nitrogen from many organisms. Urea is an important nitrogen source in agriculture, is added to many industrial products, and is a large component in wastewater. The enzyme urease hydrolyzes urea to ammonia and bicarbonate. This reaction is microbially mediated in soils, hydroponic solutions, and wastewater recycling and is catalyzed in vivo in plants using native urease, making measurement of urea environmentally important. Both direct and indirect methods to measure urea exist. This protocol uses diacetyl monoxime to directly determine the concentration of urea in solution. The protocol provides repeatable results and stable reagents with good color stability and simple measurement techniques for use in any lab with a spectrophotometer. The reaction between diacetyl monoxime and urea in the presence of sulfuric acid, phosphoric acid, thiosemicarbazide, and ferric chloride produces a chromophore with a peak absorbance at 520 nm and a linear relationship between concentration and absorbance from 0.4 to 5.0 mM urea in this protocol. The lack of detectable interferences makes this protocol suitable for the determination of millimolar levels of urea in wastewater streams and hydroponic solutions.

Wastewater recycling and the possibility of its technical use in practice

In real practice, almost half of the water, after its technical or technological use in various degrees of pollution, is drained by sewerage systems to wastewater treatment plants and subsequently discharged into the recipients of rivers and streams. The current and especially the future method of urban and industrial wastewater treatment is at such a high level that the treated water, before its discharge into the recipients, has a higher degree of quality than the flowing surface water in the watercourse. Under these ever-improving conditions and possibilities, it is appropriate to use well-treated wastewater not only for the needs of agriculture, but also as an alternative supply of fire water for fire purposes. The dislocation of wastewater treatment plants (hereinafter WWTP) in territorial cadastres with safe access to the opened level of treated water allows its relatively rapid pumping at any time, especially in conditions where there is no other suitable natural or multipurpose source of fire water. The following article suggests in a basic way how to use the given options without the risk that the treated wastewater will not endanger the health of fire brigades or will not have the negative impact on the environment of the extinguished building and its surroundings in which the fire is extinguished.

Micro-Clustering and Rank-Learning Profiling of a Small Water-Quality Multi-Index Dataset to Improve a Recycling Process

The efficiency improvement of wastewater recycling has been prioritized by ‘Goal 6’ of the United Nations Sustainable Development initiative. A methodology is developed to synchronously profile multiple water-quality indices of a wastewater electrodialysis (ED) process. The non-linear multifactorial screener is exclusively synthesized by assembling proper R-based statistical freeware routines. In sync with current trends, the new methodology promotes convenient, open and rapid implementation. The new proposal unites the ‘small-and-fast’ data-sampling features of the fractional multifactorial designs to the downsizing, by microclustering, of the multiple water quality indices—using optimized silhouette-based classification. The non-linear multifactorial profiling process is catalyzed by the ‘ordinalization’ of the regular nominal nature of the resulting optimum clusters. A bump chart screening virtually eliminates weak performances. A follow-up application of the ordinal regression succeeds in assigning statistical significance to the resultant factorial potency. The rank-learning aptitude of the new profiler is tested and confirmed on recently published wastewater ED-datasets. The small ED-datasets attest to the usefulness to convert limited data in real world applications, wherever there is a necessity to improve the quality status of water for agricultural irrigation in arid areas. The predictions have been compared with other techniques and found to be agreeable.

Food Industries Wastewater Recycling for Biodiesel Production through Microalgal Remediation

This article is an overview of a biosystem of food-industry wastewater (WW) treatment using microalgae towards circular bioeconomy through biosynthesis of compounds of added-value. Focusing on circular bioeconomy with concern to environmental pollution, the management of water-resource and energy-crisis could be combined; by upgrading conventional WW treatment and simultaneously producing a renewable and sustainable source of energy algal-lipids for biodiesel production. Phyco-remediation of food WW using microalgae has revealed many advantages that can fulfill new demands for the WW treatment. WWs can be valuable resources of micronutrients and organic content (carbon source) for algal cultivation. In this review, prospective routes for the production of value-added compounds (polysaccharides, amino acids, biofuels, and biopigments) along with the bioremediation of food industry WW have been discussed. Furthermore, limitations and issues of phyco-remediation of WW using microalgae have also been reviewed with perspectives for further research and development.