Amount Of Sludge Research Articles

Ecological mechanisms of biofilm development in the hybrid sludge-biofilm process: Implications for process start-up and optimization

The hybrid sludge-biofilm processes have been widely applied for the construction or upgradation of biological wastewater treatment process. Ecological mechanisms of biofilm development remain unclear in the hybrid ecosystem, because of the intricate interactive effects between sludge and biofilms. Herein, the establishment principles of biofilms with distinct coexisting sludge amounts were uncovered by varying sludge retention times (SRTs) from 5 to 40 days in the hybrid process. With the increasing of SRTs, biofilm biomass decreased with the increase of suspended sludge, resulting in lower biofilm proportion. As estimated by the Gompertz growth model, the increased sludge amounts (i.e., higher SRTs of 20 and 40 days) prolonged the initial colonization stage and decreased the specific development rate of biofilms when compared to lower sludge amounts with the shorter SRTs (i.e., 5 and 10 days). Null model analysis demonstrated that deterministic homogenous selection could facilitate the colonization and accumulation of biofilms with less coexisting sludge (SRT of 10 days). However, stochastic ecological drift and homogenizing dispersal dominated the colonization and accumulation stages of biofilms with more coexisting sludge (SRT of 20 days), respectively. The ecological networks reflected that positively-related taxa presented taxonomic relatedness, whereas high inconsistency of taxonomic relatedness was observed among aggregate forms or development stages as affected by varied SRTs. The high incidence of intra-taxa co-occurrence patterns suggested that taxa with similar ecological niches could be specifically selected in biofilms when being exposed with less coexisting sludge. This study uncovered ecological mechanisms of biofilm development driven by varying the SRTs of suspended sludge, which would help to propose appropriate strategies for the efficient start-up and optimization of the hybrid sludge-biofilm system.

Analysis of Machine Learning Models for Wastewater Treatment Plant Sludge Output Prediction

With China’s significant investment in wastewater treatment plants, urban sewage is effectively collected and treated, resulting in a substantial byproduct—sludge. As of 2021, a total of 2827 wastewater treatment plants have been constructed across 31 provinces, municipalities, and autonomous regions in China, with a processing capacity of 60.16 billion cubic meters. The production of dry sludge amounts to 14.229 million tons. The treatment and utilization of sludge pose significant challenges. The scientific calculation of sludge production is the basis for the reduction at the source and the design of sludge treatment and energy utilization. It is directly related to the construction scale, structure size, and equipment selection of the sludge treatment and utilization system and affects the operation and environmental management of the sludge treatment system. The wastewater treatment process using microbial metabolism is influenced by various known and unknown parameters, exhibiting highly nonlinear characteristics. These complex characteristics require the use of mathematical modeling for simulations and control. In this study, nine types of machine learning algorithms were used to establish sludge production prediction models. The extreme gradient boosting tree (XGBoost) and random forest models had the best prediction accuracies, with the former having RMSE, MAE, MAPE, and R2 values of 4.4815, 2.1169, 1.7032, 0.0415, and 0.8218, respectively. These results suggested a superiority of ensemble learning models in fitting highly nonlinear data. In addition, the contribution and influence of various input features affecting sludge output were also studied for the XGBoost model, and the daily wastewater inflow volume and surrounding temperature features had the greatest impact on sludge production. The innovation of this study lies in the application of machine learning algorithms to achieve the prediction of sludge production in wastewater treatment plants.

CONTAINER STORAGE AS AN ELEMENT OF ENHANCEMENT OF ENVIRONMENTAL SAFETY AND A STATE POLICY TOOL FOR DEALING WITH TECHNOLOGICALLY ENHANCED SOURCES OF IONIZING RADIATION

In order to implement the state environmental policy and ensure environmental safety, a number of normative legal acts, laws and state standards have been implemented on the territory of Ukraine. Special attention was paid to the State Targeted Environmental Program for the Management of Radioactive Waste, the main principle of which is the implementation of the protection of the population and the natural environment in order to create safe conditions for the existence of current and future generations and ensure sustainable development. The article highlights the results of research and development works on the development and certification of a set of packaging type IR-2 for the transportation and temporary storage of low- and medium-level solid radioactive waste KTTZ-NS-1-02.00.00, as a key element of environmental protection technologies during handling with radioactive waste. The urgent task of handling radioactive waste, which is caused by the accumulation of a significant amount of sludge in the territories of the oil and gas production complex enterprises and requires temporary storage and transportation, has been solved, as a prerequisite for increasing the efficiency of ensuring the environmental safety of the mentioned objects of formation. The technical characteristics of the packaging kit are described in detail, schematic drawings are provided, and the main parameters and dimensions of the developed packaging kit type IR-2 are provided. The scheme of the main stages of the testing of this packaging set and the certificates obtained as a result of such work, which were carried out jointly with representatives of the State Inspection of Nuclear Regulation, are presented. The developed packaging set significantly exceeds the performance of the packaging set currently used in temporary storage facilities. Keywords: environmental safety, technogenically enhanced radioactive waste, protection technologies, containers, low- and medium-level waste.

Effect of artificial interior stone sludge on physicomechanical properties of mortars

Artificial interior stone is a decorative building material, which mostly consists of quartz. Sludge is generated during the stone manufacturing process, and the amount of sludge is increasing due to the high demand; however, most of the generated sludge is disposed of in landfills. In the present study, the effects of the sludge addition on the physicomechanical properties of mortars were investigated via flowability, penetration resistance, mercury intrusion, and compressive strength tests. The independent variable was the replacement ratio of the sludge to the fine aggregate. The test results showed that the addition of the sludge reduced the flowability, and initial and final setting times, while the percentage of the pores involved in the hydrates increased. The compressive strength of mortars with the sludge was improved compared to that of the mortars without the sludge. Quantum chemistry simulations were conducted to understand the strength enhancement mechanism of the specimens, and a straightforward machine learning-based model equation was proposed by applying the experimental variables and measurement results.

Evaluating the Bioremediation Capacity of the Polychaete Perinereis gualpensis (Jeldes, 1963) for Atlantic Salmon Aquaculture Sludge

The potential of polychaetes for the bioremediation of aquaculture sludge gained more attention in recent years. These organisms can reduce organic matter and nutrients contained in the sludge of several aquaculture species, improving the sustainability of these activities. The aim of this study was to evaluate the removal performance of Perinereis gualpensis (Jeldes, 1963) being fed with aquaculture sludge produced by a recirculating system cultivating Atlantic salmon. The experiment involved adding different amounts of sludge (10% and 20% with respect to total substrate) at a density of 300 organisms m−2 during 30 days. A treatment without sludge served as a control, using natural substrate. The highest removal rate of total organic matter (TOM) (23.95 ± 13.19 g m−2 day−1) was achieved by P. gualpensis with 20% sludge addition, a reduction of about 36% compared to the total amount added at the beginning of the trials. The organisms fed with aquaculture sludge presented higher nitrogen (8–9%) and carbon (40–43%) contents, with a maximum organic carbon assimilation of 32% in relation to the total content in the sludge. The high survival (88–95%) and positive growth rates (0.28% day−1) achieved by P. gualpensis indicated that this species can be sustained with salmon sludge as the only source of food. These results indicate that P. gualpensis is a promising candidate for removing nutrients from salmon effluents. Moreover, the protein contents achieved by the organisms (52–58%) meet the dietary protein requirements of several aquaculture species. Further research is needed to determine the maximum bioremediation capacity of this species and to evaluate the lipid content and fatty acid profiles of P. gualpensis to determine its potential application in aquaculture feed.

Corrigendum: Generation and management of faecal sludge quantities and potential for resource recovery in Phnom Penh, Cambodia

Corrigendum: Generation and management of faecal sludge quantities and potential for resource recovery in Phnom Penh, Cambodia

New strategies for the management of a primary refinery oily sludge: A techno-economical assessment of thermal hydrolysis, Fenton, and wet air oxidation treatments

Petroleum refinery wastewater treatment plants produce a significant amount of oily sludge, a hazardous waste that requires proper disposal. It is necessary to develop technologies to treat and valorise it, avoiding the current environmental problems associated with its landfill disposal. This work explores the application of different advanced technologies for the pre-treatment and further valorisation of this oily sludge, which includes thermal hydrolysis, Fenton oxidation, and wet air oxidation. These treatments reduce the solid content by 51–78%. Moreover, the increasing dewaterability and settleability facilitate phase separation, thus enabling further valorisation, obtaining an aqueous effluent more biodegradable (ca. 63%). A conceptual design based on experimental data obtained at bench scale has been developed for the three pre-treatment systems under study. Techno-economic analysis of the three advanced treatments gave unitary costs ranging from 78 €/m3 for thermal hydrolysis to 192 €/m3 for the Fenton treatment, which are all in the low range of the current management cost (70–350 €/m3). Thus, the techno-economic analysis developed in this study demonstrates its feasibility compared to the current management of oily sludge from API separators. Thermal hydrolysis can be a low-cost and suitable strategy for producing biodegradable effluent that can be directly treated in the conventional biological treatment plant of the refinery. However, WAO might be a more appropriate option to recover carbon and nutrients for further valorisation in advanced biological processes.

Superparamagnetic Iron Oxide Nanoparticles as Additives for Microwave-Based Sludge Prehydrolysis: A Perspective.

Wastewater treatment plants are critical for environmental pollution control. The role that they play in protecting the environment and public health is unquestionable; however, they produce massive quantities of excess sludge as a byproduct. One pragmatic approach to utilizing excess sludge is generating methane via anaerobic digestion. For this, a prehydrolysis step can significantly improve digestion by increasing biogas quality and quantity while decreasing final sludge volumes. One of the many prehydrolysis approaches is to deliver heat into sludge via microwave irradiation. Microwave-absorbing additives can be used to further enhance thermal degradation processes. However, the implications of such an approach include potential release of said additive materials into the environment via digested sludge. In this perspective, we present and discuss the potential of superparamagnetic iron oxide nanoparticles (SPIONs) as recoverable, hyperreactive microwave absorbers for sludge prehydrolysis. Due to their size and characteristics, SPIONs pack spin electrons within a single domain that can respond to the magnetic field without remanence magnetism. SPIONs have properties of both paramagnetic and ferromagnetic materials with little to no magnetic hysteresis, which can enable their rapid recovery from slurries, even in complicated reactor installations. Further, SPIONs are excellent microwave absorbers, which result in high local heat gradients. This perspective introduces the vision that SPION properties can be tuned for desirable dielectric heating and magnetic responses while maintaining material integrity to accomplish repeated use for microwave-enhanced pretreatment.

Sludge Reduction and Surface Investigation in Electrochemical Machining by Complexing and Reducing Agents

Electrochemical machining (ECM) is widely applied to manufacture parts with complex geometries, used in electronic components and the automotive, military, and aeronautics industries. These parts have a surface shaped by controlled anodic dissolution at high current density levels, using a neutral solution of inorganic salts (i.e., NaCl or NaNO3) as the electrolyte. Such conditions generate a high amount of sludge that deposits onto the surfaces of equipment, devices, cathodes, and working pieces, requiring daily and complicated sludge management during the series production in the industry. Thus, the main goal of the present work is to propose a simple way to reduce sludge generation in the ECM industrial process. To do so, complexing (EDTA) or reducing (ascorbic acid) agents were added to the electrolyte composition, creating parallel reactions to keep the metallic ions from precipitating. The complexing agent EDTA resulted in a 30% reduction in sludge mass, using an alkaline solution (pH > 10.0). The reducing agent, ascorbic acid, resulted in a 90% reduction in sludge mass, using an acidic solution (pH < 5.0). This sludge reduction has the potential to contribute significantly to increasing equipment, devices, and cathode lifetime, as well as reducing costs associated with centrifuge or filter maintenance (sludge removal from electrolyte) and increasing the productivity of industrial ECM processes.

Efficient photocatalytic degradation of tetracycline using magnetic biochar derived by iron-rich sludge.

Industrial wastewater treatment processes produce a large quantity of iron-rich sludge due to the extensive utilization of iron salt reagent. Reuse of iron-rich sludge is an attractive route for excess sludge disposal and management. In this study, sludge-derived magnetic photocatalyst was prepared using industrial iron-rich sludge as raw materials for the first time. The photocatalytic degradation system constructed by the sludge-derived photocatalysts were evaluated using tetracycline (TC) as the target contaminant, achieving a high degradation rate of 98.3% within 5 h under optimal conditions. Major reactive oxygen species in the photocatalytic systems were investigated using radical quenching experiments and electron paramagnetic resonance spectroscopy. The results suggested that •OH and O2•- were activated by photogenerated electrons and holes, respectively. Moreover, bound persistent free radicals induced by quinone-like structure in sludge-derived biochar were the predominant factors affecting radical 1O2 formation under the light irradiation. The reactive oxygen species of •OH, O2•-, and 1O2 played main roles in the degradation of TC. The used magnetic biochar can be effectively separated and recovered in aqueous solutions by the magnetism. This method provides a new cost-effective strategy for antibiotics removal from aqueous solution.

Development and characterization of grinding sludge-reinforced aluminum-based composite by friction stir process technique

PurposeThe quantum of metal particle waste generation in manufacturing industries is posing a great concern for the environment. The iron forging industries generate a huge amount of grinding sludge (GS) waste, which is disposed into the earth. The accumulation of this waste in dump yards causes an increase in soil and air pollution levels.Design/methodology/approachIn the current investigation, an effort was made to use this waste GS for the progress of aluminum-based composite. To maintain uniform distribution of reinforcing material, the friction stir processing technique was used.FindingsThe characterization based on the SEM image of the Al/GS composite revealed that uniform dispersal of reinforcement content can be attained in a single tool pass. Number of grains/inch was approximately 2,402. XRD of GS powder confirmed the presence of SiO2, Fe2O3, Al2O3 and CaO phases. These phases proved GS to be a better reinforcement with aluminum alloy. Tensile strength and hardness were significantly improved in comparison to the aluminum alloy. Thermal expansion and corrosion weight loss were evaluated to observe the influence of GS addition.Originality/valueThe studies proved that the use of GS as reinforcement material can help in curbing the menace of soil pollution to a large extent.

A review on the recent advances in electrochemical treatment technologies for sludge dewatering and alternative uses

Municipal wastewater treatment plants generate enormous quantities of sludge as a byproduct, which not only contains a significant amount of water and harmful pathogens but also serves as a repository for a variety of essential materials and nutrients. The recovery of water and other valuable substances is highly dependent on the employed treatment methods. In recent years, electrochemical processes have attracted a great deal of interest as an efficient technique for sludge dewatering and resource recovery. By separating free and bound water from the sludge matrix, electro-dewatering can substantially reduce the volume of sludge, making it a more cost effective and sustainable method of sludge management. Furthermore, the resulting sludge cake is more manageable and transportable, making it a viable option for further disposal or resource recovery. By considering the beneficial aspects of sludge electro-dewatering, this paper aims to critically review the mechanism underlying electrochemical methods of sludge dewatering as well as modified development strategies for scal-up potentials.

Enhanced reduction of nitrate by TDER packed with surface-modified plastic particles electrodes

Based on Iron cathodes, nitrate could be selectively decomposed into other lower-valence nitrogen compounds, including ammonia, nitrogen gas, nitrite and nitric oxide, but the removal efficiencies of nitrate and total nitrogen (TN), are affected significantly by the synergistic effects of anodes, chloride electrolyte and conductive plastic particles electrodes. In this work, the base material Titanium (Ti) metal plates and plastic particles which surfaces were mainly coated with Ru-Sn oxidizing compounds, were applied as plates anodes and conductive particles electrodes in Three Dimensional Electrode Reactors (TDER). The Ti/RuSn plate anodes showed excellent performance on degrading nitrate, more nitrogen gas (83.84%) and less ammonia (15.51%) was produced, less TN and Iron ion (0.02 mg/L) was left in the wastewater, and less amount of chemical sludge (0.20 g/L) was produced. Furthermore, the removal efficiencies of nitrate and TN were further increased by the surface-modified plastic particles, which were cheap, reusable, corrosion-resistance, easy to obtain as manufactured materials and light to be suspended in waters. The degradation of nitrate and its intermediates was enhanced possibly by the continuous synergistic reactions initiated by hydrogen radicals, which was generated on the countless surficial active Ru-Sn sites of Ti/RuSn metal plate anodes and plastic particles electrodes, among residual nitrogen intermediates, most of ammonia was selectively converted to gaseous nitrogen by hypochlorite from chloride ion reaction.

Adopting Smart Integrated AgriAquaculture IAA Techniques: A Sustainable Approach by Al-Furat Al-Awsat Technical University

In light of recent developments in urban agriculture and the ongoing effects of climate change, there is a growing need for innovative irrigation practices that do not require potable water. On the other hand, significant environmental hazards are associated with the effective usage, treatment, and disposal of ever-increasing quantities of wastewater and sewage sludge in our modern times. Therefore, wastewater usage in irrigation might provide a potential alternative approach. In this regard, the water drained from fish farms is one type of wastewater capable of being employed in irrigation operations in a way that is both effective and helpful.This article highlights the efforts made by Al-Furat Al-Awsat Technical University to establish intelligent integrated AgriAquaculture (IAA) systems on its campuses as part of its strategies to achieve sustainable goals. These efforts are part of Al-Furat Al-Awsat Technical University’s more enormous efforts to achieve its goals.

Treatment of greywater by adsorption and coagulation with Hibiscus Sabdariffa as the natural coagulant

Abstract Greywater refers to wastewater from showers, baths, basins and washing machines. Recycled greywater can be used for crops irrigation, toilet flushing, and other activities that does not require fresh water. Coagulation is an effective, simple, and cheap process to treat greywater with the use of coagulants. The studies show that the use of chemical coagulants pose threat to the environment, produce large amount of sludge and have severe effect on human health. This study uses Hibiscus Sabdariffa seeds as natural coagulant, as they are biodegradable, non-toxic, and safe for human health. The seeds of Hibiscus Sabdariffa are usually discarded, thus using them as natural coagulants makes it cost-effective. Another process of adsorption was also studied in this work due to its effectiveness in treating wastewater. Activated carbon have been studied as an adsorbent due to its low-cost and sustainability. The aims of this paper are to investigate the performance of the seeds and adsorbent by differing pH, coagulant dosage, and adsorbent dosage. Jar test was carried out by varying pH of 2-12, coagulant dosage of 20-120 mg/L and adsorbent dosage of 0.5-5g. The process involved rapid mixing for 4 minutes, slow mixing for 25 minutes and 30 minutes of sedimentation time. By carrying out the experiment, it was found out the seeds of Hibiscus Sabdariffa showed best performance at pH 2, coagulant dosage 20 mg/L with the turbidity removal and COD removal of 91.3% and 43%, respectively. For the process of adsorption, highest turbidity and COD removal were determined to be 98.6% and 61.6% respectively with the pH 2 and adsorbent dosage of 3g. The combined process of adsorption-coagulation shows best performance at pH 2, coagulant dosage 4 mg/L and adsorbent dosage of 1.6g with the turbidity and COD removal of 98.3% and 85% respectively. This study shows the potential in Hibiscus Sabdariffa seeds and activated carbon to treat greywater for reuse.

Model-based development of strategies enabling effective enrichment and application of comammox bacteria in floccular sludge under mainstream conditions

The discovery of complete ammonium oxidation (comammox) has redefined the perception of the nitrification process which plays a vital part in biological nitrogen removal (BNR) from wastewater. Despite the reported detection or cultivation of comammox bacteria in biofilm or granular sludge reactors, limited attempts have been made to enrich or assess comammox bacteria in floccular sludge reactors with suspended growth of microbes, which are most extensively applied at wastewater treatment plants. Therefore, through making use of a comammox-inclusive bioprocess model reliably evaluated using batch experimental data with joint contributions of different nitrifying guilds, this work probed into the proliferation and functioning of comammox bacteria in two commonly-used floccular sludge reactor configurations, i.e., continuous stirred tank reactor (CSTR) and sequencing batch reactor (SBR), under mainstream conditions. The results indicated that compared with the studied SBR, the CSTR was observed to favor the enrichment of comammox bacteria through maintaining a sufficient sludge retention time (40–100 d) while avoiding an extremely low DO level (e.g., 0.05 g-O2/m3), irrespective of the varied influent NH4+-N of 10–100 g-N/m3. Meanwhile, the inoculum sludge was found to greatly influence the start-up process of the studied CSTR. By inoculating the CSTR with a sufficient amount of sludge, finally enriched floccular sludge with a high abundance of comammox bacteria (up to 70.5 %) could be rapidly obtained. These results not only benefitted further investigation and application of comammox-inclusive sustainable BNR technologies but also explained, to some extent, the discrepancy in the reported presence and abundance of comammox bacteria at wastewater treatment plants adopting floccular sludge-based BNR technologies.

MODELLING AND CAICULATIONS OF THE OXIGEN REGIME DURING THE EXTRACTION OF IRON FROM GROUNDWATER BY FILTRATION

On the base of the simplification of the general mathematics models of the iron removal the engineer calculation methods of the removing of the iron combinations from the ground waters by the filtration on the refine filters and at the well filter colmatation are proposed. The analysis and the comparative value of the proposed methods are carried out.
 In most regions of Ukraine, aquifers, from which water is finly taken for the population, have an increased iron content, which significantly exceeds the standarts.
 Is modern conditions, the most widespread method of extracting compounds from waters is filtering through granular loading from natural or artificial granular materials in special installations, the main element of which is a filter.
 Under normal conditions in groundwater in the absence of dissolved oxygen and other oxidizing agents, dissolved iron is mainly present in the form of Fe2+ ions or its unstable protective forms of various salts. When interacting with dissolved oxygen, which is fed into the water, divalent iron is oxidized to trivalent, and then hydrolyzed into lumpy or suspended iron hydroxide in the form of silt flakes.
 On the basis of the implementation of a more general mathematical problem and the performance of the comparative analysis carried out tat the same time, the article proposes calculation methods that allow assessing the influence of the oxygen regime. The perfomed analysis shoved that in condition of oxygen deficiency, a simpler model can be adopted. Taking into account that in the case of a homogeneous filter, a more intense accumulation of sludge occurs in the upper layers, then an important characteristic during design and operation is the determination of the concentration of the amount of sludge near the upper border of the filter.

Industrial wastewater treatment using batch recirculation electrocoagulation (BRE) process: Studies on operating parameters

The environmental industry has demonstrated an increasing interest in employing electrocoagulation (EC) process to treat industrial wastewater/effluent for recycling/drinking purposes. An iron (Fe)/aluminum (Al) plate-based batch recirculation electrocoagulation technology for wastewater treatment in the distillery industry is discussed in this work. The impact of different operational parameters, including COD, wastewater pH, current, inter-electrode spacing, combination of electrodes, recirculation flow rate, concentration of electrolytes, and treatment duration on % color, % COD reduction efficiency, and energy consumption was examined. The experimental outcomes demonstrated that, the color removal was 100 %, COD removal was 99.90 %, and energy consumption was 7.73 kWh m−3 for COD of 3600 mg L−1, current of 0.56 Amp, combination of electrodes of Fe/Fe, inter-electrode spacing of 1 cm, wastewater pH of 7, flow rate of 15 L h−1, concentration of electrolytes of 5 g L−1, and treatment time of 180 min, respectively. It was found that, a longer treatment period, higher electrolyte concentrations and current, lower COD concentrations and recirculation flow rates, Fe/Fe electrode pairings, a pH of 7, and a smaller inter-electrode spacing all contributed to increased % COD reduction efficiency. The quantity of solid sludge formed were studied with the help of operational parameters, and the results were reported. Under the optimized process conditions, the wastewater treated can be fully recovered as clean water. As a consequence of this, the results of the experiments have shown that the batch recirculation electrocoagulation process has the potential to be a more promising solution to the problem of eliminating contaminants from wastewater and industrial effluent.

Improvement of monitoring and control system for copper electrolytic refining parameters

The utilization of modern automated control systems in copper cathode production offers the opportunity for remote access to control and regulate the electrolytic process parameters. This, in turn, enhances production efficiency while reducing energy costs. The significant parameters in copper electrolytic refining encompass the temperature and composition of the electrolyte, the circulation rate of the electrolyte, the level of sludge, and the frequency of short circuits occurring between the electrodes and the current density. These parameters directly impact the quantity and volume of cathode sludge. The occurrence of short circuits within the bath arises from the growth of dendrites, necessitating the monitoring of voltage, composition, and temperature of the electrolyte. Regular analysis of the electrolyte's composition and the accumulation of sludge volume at the bottom of the electrolyzer is also necessary. The intensification of the electrolysis process primarily involves increasing the current density, reducing the electrode spacing, enhancing the quality of electrodes, improving the electrolyte circulation system, and further mechanizing and automating the process and its auxiliary operations. These efforts contribute to increased productivity. The objective of this study is to expand the capabilities of automated process control systems by incorporating sludge level control sensors. This aims to mitigate irrecoverable losses resulting from dendritic sludge short circuits on the electrodes located in the lower section of the electrolyzer, utilizing new software. A sludge level control method to prevent short circuits has been investigated, and control software employing float-type level sensors has been developed. This measure is projected to decrease energy consumption by 15–20 % and can be effectively implemented in the production of electrolytic copper at the copper smelting plant in Lao Cai, Vietnam.

Valorisation of aquaculture sludge into microbial protein using bioreactor with an optimised nutrients

The present study was conducted to optimise the nutrients used for producing high nutritional biofloc in bioreactor utilising aquaculture waste. Full Factorial design (23) of independent variables such as sludge quantity (20 and 30 gL−1), carbon nitrogen ratio (15:1 and 20:1) and bioflocculant (cationic starch) doses (30 and 60 ppm) were used for optimisation. The percentage of crude protein and crude lipid in biofloc was shown to be significantly influenced by the interaction between carbon nitrogen ratio and bioflocculant dose (BC) as well as the interaction between sludge quantity, carbon nitrogen ratio, and bioflocculant dose (ABC) (p < 0.05). The floc volume of biofloc was shown to be significantly influenced by the interaction between carbon nitrogen ratio and bioflocculant dose (BC) (p < 0.05). The optimised parameters were 30 gL−1 of sludge, a carbon nitrogen ratio of 20:1, and 30 ppm of cationic starch, which resulted in a maximum CP of 27.09%, a maximum CL of 4.36%, and a maximum floc volume of 132 mL L−1. Principal component analysis (PCA) resulted in a 2 principal components (PC 1, nutritional factors which decides the nutritional composition of biofloc and PC 2, nitrification factors which are needed for biofloc formation) that explained 85% of total data variation. This study found the production of nutritive biofloc in a bioreactor using aquaculture waste with optimised nutrients.