Biological Filter Research Articles

Permeability–selectivity trade-off for a universal leaky channel inspired by mobula filters

Mobula rays have evolved leaf-shaped filter structures to separate food particles from seawater, which function similarly to industrial cross-flow filters. Unlike cross-flow filtration, where permeability and selectivity are rationally designed following trade-off analyses, the driving forces underlying the evolution of mobula filter geometry have remained elusive. To bridge the principles of cross-flow and mobula filtration, we establish a universal framework for the permeability–selectivity trade-off in a leaky channel inspired by mobula filters, where permeability and selectivity are characterized by the pore-scale leaking rate and the cut-off particle size, respectively. Beyond the classic pore-flow regime in cross-flow filtration, we reveal transition and vortex regimes pertinent to mobula filtration. Combining theory, physical experiments, and simulations, we present distinct features of water permeability and particle selectivity across the three regimes. In particular, we identify an unreported 1/2-scaling law for the leaking rate in the vortex regime. We conclude by demonstrating that mobula filters strike an elegant balance between permeability and selectivity, which enables mobula rays to simultaneously satisfy biological requirements for breathing and filter feeding. By integrating cross-flow and mobula filtration into a universal framework, our findings provide fundamental insights into the physical constraints and evolutionary pressures associated with biological filtration geometries and lay the foundation for developing mobula-inspired filtration in industry.

Nymphaea lotus Distribution in Oguta Lake: Implications for Heavy Metal Pollution in Surface Water and Sediments

Water quality is increasingly deteriorating and has affected lakes, which are important sources of freshwater. Heavy metals are of great concern because they are mostly toxic and resistant to decomposition. Aquatic macrophytes serve as stable biological filters that purify water bodies by accumulating dissolved metals and toxins in their tissues. Given their ability to trap various toxic heavy metals, the macrophyte Nymphaea lotus, which is observed on the surface waters of Oguta Lake, was studied to estimate the concentrations of six heavy metals in the water, sediment, and macrophytes. This was achieved by studying the spatial and temporal distribution of Nymphaea lotus in the lake and analysing the concentrations of heavy metals in the surface water, macrophytes, and sediment samples. Descriptive statistics, exploratory data analysis, and correlation analysis were used to analyse data obtained. Results revealed that the population of Nymphaea lotus declines over time from June to November in all regions. Upstream had the highest concentration of macrophytes (64%), while the downstream area has the lowest (2%). The heavy metal concentrations in the three samples ranges from 0.16 mg/kg to 2.96 mg/kg in sediments and Nymphaea lotus, and from 0.16 mg/L to 2.16 mg/L in water, with lead showing the highest concentration across all sample type. This highlights heavy metal contamination in the lake. The sparsely populated Nymphaea lotus exhibits selective bioaccumulation of lead, mercury, and zinc, while it seems to exclude or inefficiently absorb arsenic and chromium. Correlation analysis suggests a close interdependence between the concentrations of metals in sediments, water, and macrophytes, with sediments playing a key role in both water contamination and macrophyte metal absorption. Corrective and preventive measures should be taken to restore the lake.

Effects of biological filtration by ascidians on microplastic composition in the water column

Plastic pollution, a widespread environmental challenge, significantly impacts marine ecosystems. The degradation of plastic under environmental conditions results in the generation of microplastic (MP; <5 mm) fragments, frequently ingested by marine life, including filter-feeders such as ascidians (Chordata, Ascidiacea). These organisms are integral to benthic-pelagic coupling, transporting MP from the water column through marine food web.Here, we explored the effect of filtration and digestion by the solitary ascidian Styela plicata on the composition of MP in the water column and on the sinking rates of faecal matter, focusing on differences between two distinct plastics, polystyrene (PS) and the biodegradable polylactic acid (PLA). The ascidians efficiently removed 2–5 μm particles within 2 h of filtration. Following digestion and secretion process, PS concentrations in water increased while PLA concentration remained stable. Some particles were egested into the water column repackaged inside faecal pellets, which significantly increased the pellets' drag force and sinking velocity. Raman spectral analysis of digested MP revealed distinct spectrum alterations due to coating by organic substances. These findings highlight the role of ascidians — and other filter-feeders— in modifying the structure of MP in their environment. Research into such modifications is crucial for understanding the MP cycle and its consequences in marine environments.

Enhanced efficiency of water purification plant by combined riverbank filtration

Water shortages occur due to several factors, with drought being one of the biggest drivers. Another major environmental issue related to the contamination of freshwater systems worldwide is thousands of micropollutants, although they generally occur at low concentration levels. The provision of safe drinking water to the population in rural developing nations remains a problem, in particular when surface water and shallow wells or non-watertight headworks wells serve as sources of drinking water. Dramatically changing raw water qualities, floods and high rainfall events anthropogenic pollution, lack of electricity supply in developing regions demand new and adapted solutions for treatment and rendering water safe for distribution. Our study aimes to find another source of water supply using riverbank filtration (RBF). The RBF is a water treatment method that removes water from rivers by pumping wells into a nearby alluvial aquifer. Several physical, chemical, and biological processes that occur underground improve the quality of surface water and eliminate the need for traditional potable water treatment. Additional treatment techniques in this process include biological degradation, sorption, and filtration. Physical, chemical, and microbiological variables were used to assess the effectiveness of the RBF system in Upper Egypt. Our study proposes a workable water treatment strategy that replaces RBF treatment or pretreatment technique for high-quality Nile water to eliminate or reduce surface water pollutants without the use of chlorine.

Bacterial and Symbiodiniaceae communities’ variation in corals with distinct traits and geographical distribution

Coral microbiomes play crucial roles in holobiont homeostasis and adaptation. The host’s ability to populate broad ecological niches and to cope with environmental changes seems to be related to the flexibility of the coral microbiome. By means of high-throughput DNA sequencing we characterized simultaneously both bacterial (16S rRNA) and Symbiodiniaceae (ITS2) communities of four reef-building coral species (Mussismilia braziliensis, Mussismilia harttii, Montastraea cavernosa, and Favia gravida) that differ in geographic distribution and niche specificity. Samples were collected in a marginal reef system (Abrolhos, Brazil) in four sites of contrasting irradiance and turbidity. Biological filters governed by the host are important in shaping corals’ microbiome structure. More structured associated microbial communities by reef site tend to occur in coral species with broader geographic and depth ranges, especially for Symbiodiniaceae, whereas the endemic and habitat-specialist host, M. braziliensis, has relatively more homogenous bacterial communities with more exclusive members. Our findings lend credence to the hypothesis that higher microbiome flexibility renders corals more adaptable to diverse environments, a trend that should be investigated in more hosts and reef areas.

Gradual Replacement of Soybean Meal with Brewer’s Yeast in Fingerling Nile Tilapia (Oreochromis niloticus) Diet, Resulting in a Polynomial Growth Pattern, Independent of Whether Reared in a Biofloc or Clear-Water System

A 60-day feeding experiment was conducted to examine whether (i) soybean meal (SBM) protein in the diet of Nile tilapia (Oreochromis niloticus) can be replaced with protein from spent brewer’s yeast (SBY); (ii) co-rearing with biofloc alters fish growth, feed conversion and protein efficiency compared with rearing in clear water; and (iii) accumulated protein quantity and quality in biofloc acts as a possible feed source for the fish in periods of low feed intake. The fish were reared in either a bio-recirculating aquaculture system (Bio-RAS) or a clear-water RAS (Cw-RAS). In Bio-RAS, the mechanical and biological filters used in Cw-RAS were replaced with an open bioreactor that delivered heterotrophic-based biofloc to the rearing tanks and also acted as a sedimentation trap for effluent water before recirculating it back into the rearing unit. The fish were fed four iso-nitrogenous and iso-energetic diets (~28% crude protein, ~19 MJ kg−1 gross energy) in which SBM protein was replaced with increasing levels of SBY, with triplicate tanks per inclusion level. The results revealed that average fish growth was greater in a biofloc environment compared with clear water and also greater at higher inclusion levels of SBY. However, in both rearing environments, fish growth displayed a second-degree polynomial distribution with increasing SBY inclusion level, with a peak between 30% and 60% inclusion. Fish in the biofloc environment showed better feed conversion ratio and protein retention, likely through ingesting both given feed and biofloc. Biofloc contained a significant amount of accumulated protein with a high biological profile, thereby constituting a possible feed reserve for the fish. A conclusion underlined by the apparent improved feed conversion of Bio-RAS reared fish, where that ingestion of biofloc will reduce the need for external feed per unit growth.

Dietary superdosing of phytase positively affects growth, mineral utilization and amino acid availability of channel catfish (Ictalurus punctatus)

The present study investigated the effects of supplementing high levels (superdosing) of dietary phytase on growth performance, mineral utilization and digestibility of amino acids in different regions of the gastrointestinal (GI) tract of fingerling channel catfish. The negative control (NC) diet was formulated with primarily soybean meal as a protein feedstuff which contributed 0.61 % total phosphorus (P) but was deficient in available P at 0.11 % of diet. Five other diets were formulated either with supplemental monocalcium phosphate at 1 % of diet in the positive control (PC), or supplemented with Quantum Blue phytase (AB Vista, Plantation, Florida) at 1000, 2000, 4000, or 8000 phytase units (FTU)/kg of diet. Groups of 20 catfish were each stocked into 24 aquaria operated as a closed, recirculating system with biological and mechanical filtration. All dietary treatments were assigned randomly to quadruplicate aquaria and initially fed at 6 % of total body weight per day. Feed quantities were adjusted weekly after weighing all fish in each aquarium as a group, and feeding levels were maintained close to apparent satiation throughout the 8-week feeding trial. Phytase supplementation significantly (P < 0.05) increased various responses of channel catfish including weight gain, feed efficiency, and protein retention compared to catfish fed the NC diet, resulting in values that were similar to catfish fed the PC diet. Moreover, catfish fed the phytase-supplemented diets had higher bone ash, calcium (Ca), magnesium (Mg), P, manganese (Mn), and zinc (Zn), as well as retention of Ca, Mg, P, iron (Fe), Mn, and Zn in whole-body tissues. Additionally, apparent availability of P from the posterior intestinal region increased with dietary phytase supplementation, with reduced excretion of nitrogen, Ca, Mg, P, copper (Cu), Mn, and Zn observed in comparison to fish fed the NC diet. Apparent digestibility coefficients for many of the indispensable and dispensable amino acids were increased by phytase supplementation, except for histidine, methionine, threonine, and taurine. This improvement in amino acid availability occurred only in the posterior region of the gastrointestinal tract. Channel catfish fed the diet containing 4000 FTU/kg diet had the highest postprandial plasma phosphorus level most of the time, except at 24 h after feeding. Based on these various responses, the optimal dietary phytase dosage was determined to average 5492 FTU/kg diet.

Electrical stimulation improves the efficiency of treating typical reclaimed water in biofilters

ABSTRACT To conduct advanced treatment on reclaimed water with a low C/N ratio and a low content of biodegradable organic matter, this paper established an biofilter-microbial electrolysis cell (BF-MEC). Through two-stage influent, the influence of electrical stimulation and electrochemical structure on the nitrogen and carbon removal of the system was explored, and the following results were obtained. The optimal externally applied voltage for the BF-MEC system is 0.55 V. The optimal structure of the BF-MEC system is an electrode spacing of 100 mm, and the optimal electrode position is when the electrode is located at the bottom of the system. Compared with the BF system, in the first stage, the removal rates of chemical oxygen demand, total ammonia nitrogen (TAN), and total nitrogen (TN) in the optimal structure BF-MEC system are increased by 13.4, 118.1, and 273.65%, respectively. In the second stage, COD, TAN, and TN removal rates are increased by up to 277.98, 115, and 722.98%, respectively. The optimal electrode position is when the electrode is located at the lower part of the system. At this time, the microbial community is more abundant, the microbial activity and lifespan are longer, and the system efficiency is optimal.

Production of biostable drinking water using a lab-scale biological trickling filter enriched with hydrogen-oxidizing bacteria

Safeguarding the drinking water quality remains a challenge from the production site to the tap. Alternatively to chemical disinfection, biostable drinking water could serve as a more sustainable approach to produce microbially safe drinking water and to maintain the microbial quality in the drinking water distribution system (DWDS). In this study, the potential of hydrogen-oxidizing bacteria (HOB) to produce biostable drinking water was examined in a continuous trickling filter supplied with hydrogen gas. A biofilm was naturally enriched for 5 months and the bacterial regrowth, invasion potential, and nutrient composition of the water were determined. Treatment improved the biostability significantly, and it is hypothesized that nutrient limitation, especially phosphorous, was a driving force. As a result, the regrowth and invasion potential were lowered, as shown with specific biostability bioassays. Overall, this study demonstrates the proof-of-concept of HOB for producing biostable drinking water through nutrient limitation.

Microplastics in an advanced wastewater treatment plant: sustained and robust removal rates unfazed by seasonal variations

Microplastics (MP), fragments of plastic generally defined as, less than 5 mm in size, originating from various urban sources, have become a significant environmental concern due to their widespread presence and potential impacts on ecosystems. This study investigates the efficiency of an advanced wastewater treatment plant discharging into the Mediterranean Sea in removing MPs from wastewater. The plant processes wastewater through a series of treatment stages, including screening, desanding, coagulation/flocculation, biological filtration, and sludge incineration. Samples were collected and analysed during three distinct campaigns (dry, rainy, and touristic seasons) to assess the plant’s performance under varying conditions. Using matrix-representative sampling methodologies and Focal Plane Array micro Fourier-Transform Infrared Spectroscopy (FPA-µFT-IR) for MP quantification, the study measured MP concentrations and removal rates. The treatment plant demonstrated high removal rates of microplastics across different periods. Using a mass balance approach, the removal efficiency during the dry sampling period was 99.85%. In the rainy campaign, the efficiency slightly decreased to 99.11% due to increased runoff, while during the touristic period, the efficiency peaked at 99.95%. Polyester was identified as the predominant polymer type. The primary treatment stages, particularly coagulation/flocculation and lamellar settling, are most effective in MP removal. The majority of MPs are retained in the sludge, which is subsequently incinerated, preventing environmental discharge. This research demonstrates that a WWTP employing advanced treatment processes is not a source of MP to the environment but rather a sink. Despite variations in influent MP concentrations across different seasons, the plant consistently maintained high removal rates, effectively mitigating MP pollution. In this study, sludge incineration further ensured that MPs were prevented from entering the environment.

GROWING OF GREEN CORAL LETTUCE AND RED HYBRID TILAPIA IN COMPACT AQUAPONIC PROTOTYPE AT DIFFERENT RECIRCULATION RATES

In this work, a compact-size aquaponics prototype was designed and fabricated. One of the current challenges in compact aquaponics systems is optimizing the balance between fish waste production and plant nutrient uptake. The objective of the work is to assess the impact of different pump recirculation rates on the crops cultivation at such compact aquaponics unit. Main components included a 50 litres fish tank, a filter unit that combines the mechanical filter and biological filter counterparts, and nutrient film technique (NFT) grower. Production of food was carried out for 10 weeks at two different recirculation rates i.e. at 50 L/hr and 75L/hr. According to the data attained, the specific growth rate (SGR) was around 5.4-5.7% with a food conversion ratio (FCR) of about 1.8-2. Moreover, the fish survival rate was 80%, and plant growth yield is about 1.5-2 cm/week. Although the level of ammonia was slightly off the acceptable limit, no yellowish colour on the leaves of the green coral lettuce was observed. The data attained signify the successful operation of compact-size aquaponics for the production of organic leafy plants and freshwater aquaculture.

Examining the efficacy of biological filters in the removal of agricultural pesticides and nutrient elements from agricultural drainage water

The high water consumption in agriculture has led to an obvious water crisis in this sector, and the use of unconventional water sources, especially agricultural drains, is considered necessary. For this purpose, the present study was carried out to evaluate the efficiency of biological filters with different types of substrates for treating agricultural wastewater in Khuzestan province, located in the south of Iran, to use receptive resources and reuse them in agriculture. Next, the efficiency of four types of biological filters for treating agricultural drainage water with different retention times was evaluated. Sawdust, cotton stalks, wheat straw, stubble, and rice husk were used as filters. Qualitative factors included agricultural pesticides (Atrazine, Randup, Paraquat, and 2, 4-D) and nutrients (nitrate, nitrogen, phosphate, and phosphorus). By examining the trend of increasing the retention time and the corresponding removal percentage, it was observed that the retention time has a direct relationship with the amount of removal efficiency of nutrients and agricultural toxins. As the residence time increases, the average amount of nutrient compounds in different filters decreases, and their removal percentage increases. The highest removal percentage of nitrate, total nitrogen, phosphate, and total phosphorus was 74.03, 71.66, 57.97, and 61.85% in the sawdust filter and was assigned to 10 days. The highest percentage of removal of Atrazine, Tofudi, Paraquat, and Roundup toxins with a removal efficiency of 91.73, 84.27, 89.81, and 88.46% was also observed in the treatment of sawdust for 10 days. The sawdust filter showed a good performance in removing the parameters of agricultural toxins and nutrient compounds in a retention time of 10 days compared to other filters and retention times. As a general result, the sawdust filter can be cited as a reliable substrate with acceptable efficiency compared to other filters.

A convection-diffusion-reaction system with discontinuous flux modelling biofilm growth in slow sand filters

A Slow Sand Filter (SSF) consists of biofilm attached to saturated packed sand with supernatant water on top, through which water flows by gravity. SSFs are used in the production of drinking water to improve water quality and remove pathogens, and, as they use biological filtration via the microbes present in the biofilm, they are simple and cheap to construct. A drawback of SSFs is that the difficult sampling and the complex dynamics associated with biofilm growth of microbes pose an obstacle for analysis and predictions. In order to overcome this issue, a mathematical model consisting of a non-linear convection-diffusion-reaction system with discontinuous flux is developed from first principles as a unified framework for the dynamics in time and depth of the biofilm and microbial community, where a variety of ecological models can be included in the reaction terms, which also contain attachment, detachment and transfer processes. The multi-phase approach considers three main physical volumes: a biofilm matrix, the water volume enclosed by it and the flowing suspension through the SSF surrounding the biofilm. The only input data needed are the inflow concentrations and rate, light irradiation and temperature. The model includes a Cahn–Hilliard-type equation for the biofilm velocity in the supernatant water. A numerical scheme that preserves physical properties of the solution is also presented. This is achieved with a time-splitting scheme using an upwind scheme with an adaptive time-step size that ensures positivity of the solution under a CFL condition and a reasonable assumption on the separate numerical solution of the Cahn–Hilliard-type equation. The latter is solved numerically with a semi-implicit finite-difference scheme using a mixed form of the equation. The flexible model framework with its numerical scheme allows for including a variety of ecological models, making the investigation and development of increasingly complex simulations possible. Simulations with different model parameters are shown to be qualitatively consistent with the literature.

EVALUATING WASTEWATER TREATMENT EFFICIENCY OF MEDICAL CENTERS IN BINH DUONG PROVINCE

This paper presents a comprehensive analysis of the wastewater management system implemented at a medical center located within the Bau Bang Industrial Park in Binh Duong province, Vietnam. With a staff of 166 and 60 beds, the facility operates in accordance with TCVN 4470:2012 General Hospital design standards, serving a diverse range of water demands including domestic, medical, and auxiliary requirements. The wastewater management system is meticulously designed to handle both rainwater and wastewater separately. Rainwater is efficiently collected through surface and roof drainage networks, while domestic and medical wastewater undergo discrete collection processes. The medical center's wastewater treatment facility, operating at a capacity of 100 m³/day, employs a multistage treatment process to ensure compliance with stringent regulatory standards (QCVN 28:2010/BTNMT, column B, K = 1). This process includes preliminary treatment, anaerobic and aerobic biological treatment, membrane filtration, and disinfection. The facility consistently meets quality parameters outlined in QCVN 28:2010/BTNMT, exhibiting effective removal rates for organic pollutants, suspended solids, ammonia, phosphates, and pathogens. Furthermore, the medical center demonstrates commendable environmental stewardship through its stormwater drainage infrastructure, which integrates seamlessly with the local drainage network, safeguarding against environmental contamination. Overall, the wastewater management practices at the medical center exemplify best practices in environmental management within the healthcare sector. This study provides valuable insights into the design, implementation, and performance evaluation of wastewater treatment systems in industrial settings, contributing to the global discourse on sustainable wastewater management practices.

Innovations in Aquaponics Technology and Building Sustainable Infrastructure for Agriculture

Aquaponics, a symbiotic integration of aquaculture and hydroponics, presents a promising approach to sustainable agriculture by maximizing resource utilization and minimizing environmental impact. This study explores recent innovations in aquaponics technology and the development of sustainable infrastructure to support its widespread adoption. A systematic literature review is conducted, showing the fundamentals of aquaponics and its key components such as fish tanks, grow beds, and biological filters. Innovations in technology are examined, including advanced monitoring and control systems, integration of renewable energy sources, automation, and novel growing techniques. Sustainable infrastructure for aquaponics is analyzed, focusing on water management strategies, energy efficiency measures, material selection, and integration with urban agriculture. Furthermore, the alignment of aquaponics technology and sustainable infrastructure development with the United Nations Sustainable Development Goals (SDGs) is studied, particularly in achieving goals related to zero hunger, clean water and sanitation, responsible consumption and production, and climate action.

Assessment of environmental sustainability of drinking water treatments for arsenic removal

To date, few studies that developed a complete Life Cycle Assessment (LCA) are available in literature, but they are limited to non-conventional processes and did not take into consideration the entire drinking water treatment plant (DWTP). Moreover, few data of the environmental impact are currently available for some of the most widely applied technologies such as biological filtration and coagulation. This study aims to overcome this research gap carrying out a LCA in order to identify (i) what is the most impactful process, and (ii) what possible solutions for mitigating the impact can be proposed. Focusing on the treatment for arsenic removal, the results showed that coagulation was the most impactful process mainly due to the electricity consumption while, looking at the entire DWTP, disinfection prevails. In view of potential up-grade, the use of green energy can effectively increase the sustainability.

Risk of hydrogen sulfide pollution from pressure release resulting from landfill mining

Landfill mining (LFM) has gained widespread recognition due to its benefits in terms of resource utilization of landfill waste and reuse of landfill sites. However, it is important to thoroughly assess the associated environmental risks. This study simulated the pressure release induced from LFM in small-scale batch anaerobic reactors subject to different initial pressures (0.2–0.6 MPa). The potential risk of hydrogen sulfide (H2S) pollution resulting from pressure release caused by LFM was investigated. The results demonstrated that the concentration of H2S significantly increased following the simulated pressure treatments. At the low (25 °C) and high (50 °C) temperatures tested, the peak H2S concentration reached 19366 and 24794 mg·m−3, respectively. Both of these concentrations were observed under highest initial pressure condition (0.6 MPa). However, the duration of H2S release was remarkably longer (>90 days) at the low temperature tested. Microbial diversity analysis results revealed that, at tested low temperature, the sulfate-reducing bacteria (SRB) communities of various pressure-bearing environments became phylogenetically similar following the pressure releases. In contrast, at the high temperature tested, specific SRB genera (Desulfitibacter and Candidatus Desulforudis) showed further enrichment. Moreover, the intensified sulfate reduction activity following pressure release was attributed to the enrichment of specific SRBs, including Desulfovibrio (ASV585 and ASV1417), Desulfofarcimen (ASV343), Candidatus Desulforudis (ASV24), and Desulfohalotomaculum (ASV506 and ASV2530). These results indicate that the pressure release associated with LFM significantly increases the amount of H2S released from landfills, and the SRB communities have different response mechanisms to pressure release at different temperature conditions. This study highlights the importance of considering the potential secondary environmental risks associated with LFM.

The use of biofilters in the treatment of wastewater containing organic substances

Abstract The lack of sufficiently effective treatment of wastewater generated in industry and domestic life remains one of the most acute environmental problems. Domestic wastewater is characterized by a high content of organic impurities in its composition, which determines the specifics of the choice of treatment technologies. One of the most relevant and effective methods is biological purification carried out in biological filters. This article discusses the problems associated with wastewater treatment of a sanatorium compound. The analysis of the content of various components in the water supplied to the treatment was carried out, the efficiency of the treatment equipment was determined. The paper proposes and substantiates the expediency of using a modern type of synthetic ruff biofilter media to increase the cleaning efficiency of the wastewater and their compliance with regulatory requirements for discharge into a water body.

A Review Paper on Bioremediation, A Panacea to Aquaculture Productivity

Aquaculture production encompasses the cultivation of aquatic organisms, including fish, shellfish, and plants, within controlled environments, playing a pivotal role in meeting the escalating global demand for fish and seafood. Various techniques are employed, ranging from fish farming in ponds, cages, or tanks to the cultivation of seaweed and other aquatic flora. The overarching objective is to achieve sustainable production while minimizing adverse environmental impacts. The utilization of bioremediation techniques in aquaculture entails harnessing microorganisms to degrade pollutants and ameliorate water quality, thereby fostering a healthier environment conducive to the thriving of aquatic organisms. Strategic interventions, such as the introduction of specific bacteria or plants capable of absorbing excess nutrients, contribute to ecosystem equilibrium, thereby promoting sustainable aquaculture practices. Leveraging living organisms to detoxify or eliminate pollutants represents a promising strategy for addressing environmental challenges associated with intensive aquaculture. The review delves into elucidating the mechanisms underlying microbial communities and selected organisms' capacity to mitigate water quality issues, notably excess nutrients and organic matter accumulation. Common bioremediation approaches encompass the utilization of beneficial bacteria, denitrifying bacteria, Nano remediation, biological filters, bioaugmentation, and oxygenation. By integrating these bioremediation techniques, aquaculture enterprises can bolster water quality, mitigate disease risks, and foster a more sustainable and productive aquatic environment conducive to the flourishing of aquatic organisms.

Optimum Tuning for the High-efficiency Removal of Malodorous Gas Containing Hydrogen Sulphide Using Biological Treatment

Hydrogen sulfide, as the main pollutant causing stench, has always been one of the main problems in environmental protection. In order to promote the practical application, a pilot study was carried out in this work on the biological treatment of hydrogen sulfide malodorous gas by the combined process of biological drip filtration on the basis of our previous laboratory-scale experiments. After enlarging the reactor in pilot experiment, various factors affecting the deodorization efficiency are compared in pilot scale and laboratory scale, and the optimum pilot condition are obtained. Furthermore, the mechanism of biological deodorization is analyzed. Based on the results of the comparison between the previous laboratory-scale and the pilot-scale of this work, possible bottlenecks and challenges of biological deodorization technology from pilot to industrial application are discussed. The technical approach proposed in this work provides an economical and efficient feasible scheme for biological deodorization in the industrial practice.