Sludge Accumulation Research Articles

Performance of DOuble Circulation Anaerobic Sludge bed reactor: Biomass self-balance

The calcification of Anaerobic Granular Sludge is a serious problem in the application of anaerobic methanization biotechnology. Regular replacement of calcified sludge with exogenous sludge is an effective method, but it is costly and troublesome. A new DOuble Circulation Anaerobic Sludge bed reactor was developed for the enhanced production of endogenous sludge to self-balance the discharge of calcified sludge. The sludge washout rate was demonstrated to fall by 45% and the sludge proliferation rate was shown to rise by 230%, offsetting the regular discharge of calcified sludge. The zoogloea in 100 μm dimension was revealed to be the intermediate component of sludge. The sludge proliferation mode was proposed as follows: (i) Growth of sludge; (ii) Self-cracking of sludge to release fragmental sludge; (iii) Migration of fragmental sludge by self-floatation; (iv) Accumulation of suspended sludge in the sedimentation chamber; (v) Re-granulation of suspended sludge with the aid of Venturi effect.

Distribution Characteristics of Inorganic Solids in Biochemical Treatment System

This paper studies the accumulation mechanism of different types of inorganic solids in activated sludge system by taking two main kinds of inorganic solids-chemical sludge and sediment as the research object. In the chemical phosphorus removal experiment, self-made calcium silicate hydrate was used as the chemical phosphorus removal agent and added to the end of the biochemical system of domestic sewage for phosphorus removal experiment, while the fine sediment was simulated by quartz sand of 26, 73, 106, 165 and 210 μm respectively, and a complete mixture model of inorganic solid accumulation was established as Xiss =Ciss, inf × (SRT/HRT + 1) × (1 – e–t/SRT). The results showed that the self-made hydrated calcium silicate had good phosphorus removal effect, and the TP of domestic sewage could be removed from 7 mg/L to 0.5 mg/L. The chemical sludge accumulation in the phosphorus removal process conforms to the complete mixing model, and the relative errors of measured and predicted values of MLVSS/MLSS and MLISS were 1% and 3%, respectively. The sediment accumulation process does not conform to the completely mixed model. The relative error of MLVSS/MLSS is between 56% and 77%, and that of MLISS is between –45% and –80%. The accumulation forms of inorganic solids in different forms of activated sludge systems are also different. Chemical sludge is mainly suspended in the mixture, reducing the proportion of MLVSS/MLSS. In activated sludge system, sediment is accumulated in various forms such as suspension and deposition.

Quality assessment of Litopenaeus vannamei postlarvae produced in some commercial shrimp hatcheries of Choubdeh Abadan, Iran

In the present study, the quality of Litopenaeus vannamei postlarvae (PL) produced in some commercial hatcheries evaluated in three different hatcheries with different management in Chouebdeh Abadan, Iran. For evaluating management effects on PL quality, 180 postlarvae (30 postlarvae for each quality index) sampled from three hatcheries during the two sampling periods. Then morphometric indices (including body weight, total length, carapace length, length of the intestine, diameter of the sixth abdominal segment), behavioral indices (swimming activity), stress test (salinities of 0%, and 50%, formalin 100 and 200 ppm), carcass biochemical compositions, microbial indices, and microscopic observations) were analyzed and recorded. Management features assessed using a questionnaire. Based on the results, the highest morphometric indices were attributed to hatcheries 2 & 3. Also, the hepatopancreas index in hatchery no. 3 was better than other hatcheries. Similarly, the highest survival rate in the stress test and behavioral index were observed in the PLs of hatchery no. 3. The results of carcass biochemical composition also showed that carcass lipid decreased by increasing carcass protein content. The highest bacterial load was observed in the PLs of hatchery no. 2. The results of microscopic observations indicated that the post-larvae in the third hatchery had a completely dilated intestine and contained more food. The hepatopancreatic tissue was larger and consisted of multiple B cells with large vesicles. Based on the questionnaire, all PL samples were in PL 12 stage. The main differences between hatchery no. 3 and other hatcheries were as follows: The broodstocks weight was higher than other hatcheries; fresh and formulated diet was used in hatchery no. 3; larval growth assay, nauplius, and postlarval survival assay was carried out on a regular basis, and no sludge accumulation at the bottom of the tanks was observed in hatchery no. 3. The results of this research show that appropriate management, in hatchery no. 3 in comparison to other hatcheries, is considered as the main factor resulting in better quality for postlarvae production.

Enhancement of Biogas Production in Anaerobic Digestion from Sludge of Dairy Waste with Fixed Bed Reactor by Using Natural Zeolite

In dairy waste treatment plant, there was sludge accumulation of material organic sediment on the bottom of the container. This sludge has a very strong odor, brownish and high organic content. Commonly used as fertilizer, animal feed, and biodiesel production. An alternative treatment processed by using anaerobic digestion is used in this study to produce biogas. The sludge was placed in anaerobic fixed bed continuous reactor with packing media support variation using bioball, natural zeolite, and bioring. The reactor was operated in batch 21 days with volume 30 liters. The effect of differences supported media on biogas production was investigated. In this study was obtained that fixed-bed reactor with supported zeolite media was the highest biogas production and sCOD removal up to 89.66%.

Effects of pharmaceutical load on the effluent quality using sequencing batch reactor

The effect of pharmaceutical load on the performance of laboratory scale sequencing batch reactor (SBR) in terms of effluent quality and sludge settling ability was studied. The SBR was operated using low-strength domestic wastewater and spiked with a unique combination of drugs namely atenolol, gliclazide and prazosin after 21 days of reactor operation. Atenolol and gliclazide were spiked at concentration of 1000 µg/l while 100 µg/l for prazosin. Several parameters were observed which includes concentration of COD, ammonia, MLSS and SVI30. The effluent quality and sludge settling ability before and after drugs introduction were compared. The average COD removal efficiency before and after the introduction of pharmaceutical was 85% and 74%, respectively. The average ammonia removals were 84% and 62% before and after addition of pharmaceutical respectively. MLSS and SVI30 values was successfully maintained within desired value at the end of experiment indicating good sludge accumulation and sludge settling ability.

Fate of micropollutants in chemically enhanced primary treatment using recovered coagulants

In this study, the fate of several micropollutants (MPs) in wastewater due to coagulation using both fresh and recovered aluminum and iron coagulants was determined. 18 MPs from different groups such as antibiotics, food additives, and surfactants were selected and spiked into the primary influent collected from a local wastewater plant. The distribution of MPs in the recovered coagulant and treated effluent after coagulation was determined for both fresh and recycled coagulants. The distribution of MPs in wastewater and the removal during coagulation were compound specific; MPs with log Kow < 2.5 were predominantly present in the effluent after coagulation, while MPs with log Kow > 2.5 were sorbed on the coagulated sludge. The distribution ratio (Kd) of all the MPs (diclofenac, clarithromycin, etc.) with log Kow > 2.5 was determined along with their extent of accumulation in sludge due to the recycling of coagulants. Compounds such as sulfamethoxazole, erythromycin and sulfathiazole, showed low removal during coagulation. The tetracycline group of compounds showed possible chelation with iron and aluminum. Only <10% of the initially spiked MPs with log Kow > 2.5 was being recycled with the recovered coagulant, thus alleviating the concern of accumulation of the MPs during recycle of the coagulants.

Key management rules for agricultural alpine newt breeding ponds based on habitat suitability models

The alpine newt, Ichthyosaura alpestris, is very sensitive to habitat destruction and alteration which has led to declining populations across Europe. As this species is protected through the Bern Convention, it is essential to have a comprehensive understanding of its habitat requirements to ensure proper conservation measures. We trained, validated and optimized classification tree models based on data on local aquatic habitat conditions from 125 farmland ponds scattered over Belgium and Luxembourg where the alpine newt commonly occurs. To obtain user-friendly and representative models, data was pre-processed and stratified after which different degrees of pruning were applied for model optimization. In order to check the model’s applicability for management, we predicted alpine newt occurrence with an independent dataset. The most robust and reliable model revealed that fish absence was the major driving factor followed by the thickness of the sludge layer. We found that fish presence established alpine newt absence and that fishless ponds with a sludge layer of 15 cm or more were predicted to host no alpine newts. The latter provides quantitative information for decision makers. Moreover, our results indicated that the amount of sludge could be associated with eutrophication and erosion. Regarding management practices, it is advised to assure the absence of fish and reduce sludge accumulation in ponds designated for the conservation of alpine newts, for example by designing temporary ponds not fed through fish-containing surface waters. Furthermore, we recommend to install buffer strips around a pond to reduce nutrient and soil run-off from the terrestrial environment.

Ciprofloxacin adsorption by biochar derived from co-pyrolysis of sewage sludge and bamboo waste.

Antibiotics residues in aqueous environment and sewage sludge accumulation have become serious environmental issues. The aim of this study is to investigate the potential of ciprofloxacin (CIP) removal by sludge-based biochar prepared from co-pyrolysis of sewage sludge and bamboo waste (BW). The stability and environmental risk of heavy metals (HMs) in the biochar were further investigated to evaluate potential risks for biochar utilization. Results showed that BW was an outstanding additive to prepare co-pyrolyzed biochar from sludge. A higher CIP removal rate (95%) of BW-sludge biochar (SBC) was obtained under initial CIP concentration of 10mg/L, and its maximum adsorption capacity was 62.48mg/g which was calculated from the Langmuir model. The pseudo-second-order and Freundlich model also well fit the CIP adsorption process, indicating a chemical and multilayer adsorption of CIP on a heterogeneous surface of biochar. Adsorption mechanism analysis indicated that the diverse functional groups and Fe species in biochar probably were the dominant factors in the adsorption of CIP. The π-π interaction, H-bond, ion exchange, and Fe-complexation might be the main interactions between the functional species and CIP molecules. Besides, HMs, especially the Cr, Cd, and As, were well immobilized in SBC compared with pure sludge biochar. This work suggested that sludge-based biochar, especially the co-pyrolyzed SBC, could be a potential adsorbent for CIP removal from aqueous solutions.

Bio‐electro‐Fenton systems for sustainable wastewater treatment: mechanisms, novel configurations, recent advances, LCA and challenges. An updated review

AbstractBio‐electro‐Fenton processes use biological electrons produced from bioelectrochemical systems to treat wastewater. The most significant advantages of bio‐electro‐Fenton systems are high effectiveness, low toxicity, gentle operation conditions, environmentally friendly treatment without sludge accumulation and energy conservation. Though promising, bio‐electro‐Fenton systems still face several challenges, such as high power density, H2O2 concentration, cathode materials, Fe2+ concentration and pH. This review comprehensively discusses the mechanisms of bio‐electro‐Fenton systems. Then, structural configurations are critically reviewed, including microbial fuel cells coupled with electro‐Fenton systems, microbial electrolysis cells coupled with electro‐Fenton systems and other bioelectrochemical systems coupled with electro‐Fenton systems. Furthermore, recent advances in bio‐electro‐Fenton systems for wastewater treatment are introduced, including dye solution, pharmaceuticals and personal care products, oily wastewater, landfill leachate and other pollutants. In addition, the current challenges and specific future prospects of bio‐electro‐Fenton, such as possible mechanisms for improving the power output, electrode materials that are potentially useful, self‐designed electrodes and methods of maintaining circumneutral pH values, are also explored. Heretofore, great progress in bio‐electro‐Fenton has been made, but further improvements are still needed in order to make this system more economical and practical. © 2020 Society of Chemical Industry

Research on actual conditions of waterfront space utilization and management by designated managers in Tokyo Marine Parks

In this study, we surveyed the utilization and management of waterfront space of Tokyo Marine Parks by designated managers of the parks and clarified the current issues. In the survey, regarding the utilization, we focused on the events using waterfront space held in the parks with sea level. Also, regarding the management, we targeted the parks with the beach and focused on the contents of the management plan of beach maintenance, the recognition and the treatment by designated managers. As a result of the survey, the event was confirmed to be held at seven parks, and 60% of it utilized waterfront space. However, there were the parks that hardly used the waterfront space. Also, events for environmental protection were limited. On the management side, the management plans for problems requiring specialized knowledge, such as sludge accumulation and clogging on the beach, could not be confirmed. And, it was found that the recognition and the treatment of the designated manager were also insufficient.

PURIFICATION OF SEWAGES GALVANIC PRODUCTIONS: ECOLOGICAL AND ECONOMIC ASPECTS

There is an urgent need for copper in Ukraine, which is used in various industries: electrical engineering,mechanical engineering, construction, food and chemical industries. Meanwhile, there is insufficient exploration ofcopper ores in Ukraine. At the same time, galvanic and PCB manufacturing are sources of environmental hazard.The object of the study is the process of using copper from sewage production boards and electroplating processes.The purpose of the work is environmental and economic justification for the removal of copper from wastewater forits further use. The aspects of mining (copper) in a mine and open method are described. The data on exploredreserves of copper ores in Ukraine and real needs for copper for the successful operation of industrial enterprisesare presented. The condition with the presence of sludge during the work of the etching lines of the printed circuitboards during normal operation at full capacity is considered, and it is established that for the productivity of theetching line 14 m2 / h the amount of sludges per month of work in one shift will be about 2400-2500 kg. This leadsto the accumulation of significant amounts of hazardous waste on the territories of enterprises, which causeenvironmental damage. In order to avoid the accumulation of sludge on the territory of the enterprises it is proposedto use the technology of regeneration of waste digestion solutions, in which the recovered metal is used as secondaryraw material for copper production, and the recovered solution is reused for etching of printed circuit boards. Thescheme of the line of etching of printed circuit boards with a lead for regeneration is offered. The introduction of anew wastewater treatment technology with only one plant can bring more than 2.8 million UAH of economic effect.The total sludge hazard index for the current state of sludge storage in the territory of enterprises (0.045) and afterthe implementation of wastewater recovery (100) has been determined.

Effect of Arbuscular Mycorrhizal Fungi and Phosphate-Solubilizing Bacteria Consortia Associated with Phospho-Compost on Phosphorus Solubilization and Growth of Tomato Seedlings (Solanum lycopersicum L.)

ABSTRACTThe exploitation of phosphate mines generates an important quantity of phosphate sludge that remains accumulated and not valorized. In this context, composting with organic matter and rhizospheric microorganisms offers an interesting alternative and that is more sustainable for agriculture. This work aims to investigate the synergetic effect of arbuscular mycorrhizal fungi (AMF), phosphate-solubilizing bacteria (PSB) and phospho-compost (PC), produced from phosphate-laundered sludge and organic wastes, and their combination on plant growth, phosphorus solubilization and phosphatase activities (alkaline and acid). Inoculated mycorrhizae and bacteria strains used in this study were selected from plant rhizosphere grown on phosphate-laundered sludge. Significant (p < .05) increases in plant growth was observed when inoculated with both consortia and PC (PC+ PSB+ AMF) similar to those recorded in plants amended with chemical fertilizer. Tripartite inoculated tomato had a significantly (p < .05) higher shoot height; shoot and root dry weight, root colonization and available P content, than the control. Co-inoculation with PC and AMF greatly increased alkaline phosphatase activity and the rate of mycorrhizal intensity. We conclude that PC and endophytic AMF and PSB consortia contribute to a tripartite inoculation in tomato seedlings and are coordinately involved in plant growth and phosphorus solubilization. These results open up promising prospects for using formulate phospho-compost enriched with phosphorus-solubilizing microorganisms (PSM) in crop cultivation as biofertilizers to solve problems of phosphate-laundered sludge accumulation.

Study of hydrogeological conditions to ensure security of mining at Sokolovsky iron-ore deposit

Introduction. Complex hydrogeological conditions of the rock mass at Sokolovsky deposit are the cause of constant search for new solutions for industrial safety improvement. At the present time there is much information on engineering and geological conditions of the field rock mass which is a source of measures developed to ensure industrial safety and technological solutions in mining. Research aim. With the purpose of determining a tactics of mining security support, the information on the hydrogeological and engineering-geological conditions of Sokolovsky field was analyzed. Methodology. The article provides the details of Sokolovsky field structure. The factors have been revealed which are hazardous for mining: undrained hydrogeological horizons and complexes, karst, thixotropic rock within the open pit. These factors create the conditions for sludge and water accumulation and rush into the underground mine. The majority of sandshale rushes fall upon the main production horizons into the intake and transportation mine workings. Results. Directions have been determined for further investigation of the mechanism of hazardous phenomena development and realization in geological environment of the field; the investigation is directed at improving catastrophe prevention measures and personnel security measures. Summary. Currently, at the stage of field development, there emerged a need to study particular hydrogeological and geomechanical conditions in details in order to increase of effectiveness of drainage at local sites of the mass which are designed for ore extraction.

Effect of loading rate and sludge deposit on a VFCW treating septage

A pilot-scale vertical flow constructed wetland (VFCW) was constructed and operated to treat septage based on hydraulic loading rate (HLR). The flow pattern illustrated that the highest hydraulic gradient existed in the deepest ponding leading to peak effluent flow rates. However, the hydraulic performance was found to be highly varying with respect to HLR. It is attributed to the accumulation of sludge deposit that produced preferential flow pathways in the wetland beds. The pilot-scale VFCW was able to retain 95% of TS, COD, and TN with sufficient sludge thickness regardless of the HLR variation. However, and in the effluent are strongly correlated to the effluent flow rate, and the associated treatment efficiency is lower. Due to its promising solids removals, HLR is recommended as a practical feeding strategy as it offers a simple application and the ability to control overflow.

Conditioning with zero-valent iron or Fe2+ activated peroxydisulfate at an acidic initial sludge pH removed intracellular antibiotic resistance genes but increased extracellular antibiotic resistance genes in sewage sludge

Sulfate radical (SO4−)-based conditioning methods, such as zero-valent iron (ZVI, i.e., Fe0) or ferrous iron (Fe2+) activated peroxydisulfate (S2O82-), have recently developed to improve sludge dewaterability, but it remains unclear how they impact the intracellular and extracellular antibiotic resistance genes (ARGs) in sewage sludge. In this study, it was found that conditioning treatments that used ZVI/S2O82- or Fe2+/S2O82- system, at an acidic initial sludge pH, removed the intracellular ARGs and intI1 and the extracellular intI1 from sewage sludge, but led to the accumulation of extracellular ARGs of aadA-01, aadA-02, aadA1, aadA2-03, and strB in conditioned sludge. During sludge conditioning with ZVI/S2O82- or Fe2+/S2O82-, bacterial hosts of ARGs and intI1 were seriously lysed to release the intracellular ARGs and intI1 to the extracellular environment, thus removing intracellular ARGs and intI1 in sludge, while the released ARGs and intI1 were primarily degraded by the produced SO4− to attenuate most extracellular ARGs and intI1. However, the relatively lower degradation ability of SO4− for extracellular ARGs of aadA-01, aadA-02, aadA1, aadA2-03, and strB led to their accumulation in conditioned sludge. Therefore, SO4−-based conditioning methods can be employed to reduce ARGs in sludge, but the subsequent treatment of sludge dewatering filtrate requires more attention.

High-Resolution Bathymetry Mapping of Water Bodies: Development and Implementation

Traditionally, bathymetry mapping of ponds, lakes, and rivers have used techniques which are low in spatial resolution. Waste stabilisation ponds (WSPs) are utilised worldwide for wastewater treatment, and throughout their operation require periodic sludge surveys. Sludge accumulation in WSPs can impact performance by reducing the effective volume of the pond, and altering the pond hydraulics and wastewater treatment efficiency. Traditionally, sludge heights, and thus sludge volume, have been measured using techniques such as the 'sludge judge' and the 'white towel' test. Both of these methods have low spatial resolution, are subjective in terms of precision and accuracy, are labour intensive, and require a high level of safety precautions. A sonar device fitted to a remotely operated vehicle (ROV) can improve the resolution and accuracy of sludge height measurements, as well as reduce labour and safety requirements. This technology is readily available; however, despite its applicability, it has not been previously assessed for use on WSPs. This study aimed to design, build, and assess the performance of an ROV to measure sludge height in WSPs. Profiling of several WSPs has shown that the ROV with autonomous sonar device is capable of providing bathymetry with greatly increased spatial resolution in a greatly reduced profiling time. To date, the ROV has been applied on in excess of 400 WSPs across Australia, several large lakes, stormwater retention ponds, river beds, and drinking water reservoirs. ROVs, such as the one built in this study, will be useful for not only determining sludge profiles, but also in calculating sludge accumulation rates and in evaluating pond hydraulic efficiency. As demonstrated, this technology is not limited to application in wastewater management, with the potential for wider application in the monitoring of other small to medium sized water bodies, including reservoirs, lakes, channels, recreational water bodies, river beds, mine tailing dams and commercial ports.

Evaluation of the methods of separation into phases of the emulsion of the intermediate layer formed in the process of oil preparation

The paper considers the problem of the accumulation and disposal of oil sludge, which include a stable oil-water emulsion, and the main causes of the formation of oil-water emulsion. It also gives a classification of separation methods. The results of experimental data on the analysis of hot sludge and centrifugation methods using demulsifiers are presented: DIN 12D 2018, DIN 12D 2017, SNPH, KR-11DE.

New insight into filamentous sludge bulking during wastewater treatment: Surface characteristics and thermodynamics

Although there have been many studies on filamentary bulking of activated sludge, it has been revealed that there is still a gap in the microscopic mechanism of filamentary bulking. In this study, the surface characteristics and thermodynamics of sludge floc were investigated to reveal the mechanism of filamentous sludge bulking. The results showed that the EPS content gradually decreased from 71.09 mg/g VSS to 40.00 mg/g VSS and the protein (PN) content of the EPS significantly decreased from 64.10 mg/g VSS to 35.85 mg/g VSS during sludge bulking. The variation in the EPS and its components led to a decrease in the relative hydrophobicity of sludge and an increase in surface negative charge; then, deterioration of the flocculation setteability of sludge flocs occurred. The electric double layer (WR) was the main force determining the aggregation of sludge during sludge bulking. The total energy of the interaction (WT) increased during sludge bulking, which led to an increase in the difficulty of sludge accumulation. This study is useful for understanding the filamentous bulking of sludge within an activated sludge process.

The Role of Environmental Variables in Waste Stabilization Ponds' Morphodynamics

In management of helminth infections and transmission, the correct prediction of sludge accumulation patterns in waste stabilization ponds (WSP) is important as sedimented eggs are associated with sludge depth. However, sedimentation in WSP is complicated by the non-stationary nature of the inputs and environmental factors such as weather variables, that are mostly site specific. This paper investigates sludge accumulation patterns in the Buguruni WSP (in Dar es Salaam, Tanzania) and the role that wind and increased run-off during rainy season play. Sludge depths were measured twice; in January 2017 and January 2018. Higher sludge depths were observed close to the inlet, indicating that more helminth eggs may be recovered in the sludge around this area. A sedimentation model set in Delft3D successfully reproduced the sludge accumulation pattern near the inlet, with wind and inflow characteristics as the major driving factors. The pond inlet receives more solids and water during the rain season as a result of defective pipes and manholes, and simulations show that this has significant impacts on sludge accumulation. Improved sludge depth measurement and wind and discharge data will improve modelled sludge accumulation patterns to capture those away from the inlet. Our research has shown that neglecting maintenance of the pond, as well as the sewer system has potential severe health and environmental effects, impacting communities downstream of the WSP. This research also shows the important role that numerical modelling can play in sustainable management of WSP.

Smart Sanitary Disposal System in Hard Rock Exposures Using Microbes

Septic system plays a major role in sanitary disposal activities. In developing country it is very essential for proper disposal of wastes for providing clean environment. In our country the government has adopted scheme, “CLEAN INDIA”,. For achieving this aim, the septic system is necessary to construct in each and every residential, commercial buildings and public areas. Septic tank systems are a type of simple onsite sewage facility.But groundwater pollution may occur and can create a problem. Usage of mobile septic tank can be helpful to avoid such problem. In this present investigation an idea has been arrived and the septic tank constructed by the way which have been tested for 10 days for decomposition using microbes. The term ‘septic’ refer to the anaerobic bacteria environment that develops in the tanks which decomposes or mineralizes the water discharged into the tank. The rate of accumulation of sludge is faster than rate of decomposition. So in our project we have used microbes for decomposition.In urban areas, construction of septic tanks are easier. But in rock exposures, the septic tanks cannot be constructed easily. In this paper, the problem is solved by giving an idea as solution by providing a “MOBILE SEPTIC TANK”. This will be helpful and eliminate such problems.