High Harvesting Costs Research Articles

Lightweight-Improved YOLOv5s Model for Grape Fruit and Stem Recognition

Mechanized harvesting is the key technology to solving the high cost and low efficiency of manual harvesting, and the key to realizing mechanized harvesting lies in the accurate and fast identification and localization of targets. In this paper, a lightweight YOLOv5s model is improved for efficiently identifying grape fruits and stems. On the one hand, it improves the CSP module in YOLOv5s using the Ghost module, reducing model parameters through ghost feature maps and cost-effective linear operations. On the other hand, it replaces traditional convolutions with deep convolutions to further reduce the model’s computational load. The model is trained on datasets under different environments (normal light, low light, strong light, noise) to enhance the model’s generalization and robustness. The model is applied to the recognition of grape fruits and stems, and the experimental results show that the overall accuracy, recall rate, mAP, and F1 score of the model are 96.8%, 97.7%, 98.6%, and 97.2% respectively. The average detection time on a GPU is 4.5 ms, with a frame rate of 221 FPS, and the weight size generated during training is 5.8 MB. Compared to the original YOLOv5s, YOLOv5m, YOLOv5l, and YOLOv5x models under the specific orchard environment of a grape greenhouse, the proposed model improves accuracy by 1%, decreases the recall rate by 0.2%, increases the F1 score by 0.4%, and maintains the same mAP. In terms of weight size, it is reduced by 61.1% compared to the original model, and is only 1.8% and 5.5% of the Faster-RCNN and SSD models, respectively. The FPS is increased by 43.5% compared to the original model, and is 11.05 times and 8.84 times that of the Faster-RCNN and SSD models, respectively. On a CPU, the average detection time is 23.9 ms, with a frame rate of 41.9 FPS, representing a 31% improvement over the original model. The test results demonstrate that the lightweight-improved YOLOv5s model proposed in the study, while maintaining accuracy, significantly reduces the model size, enhances recognition speed, and can provide fast and accurate identification and localization for robotic harvesting.

Harvesting of Arachis hypogaea L. in an Italian Area: Synergy between Cultural Techniques and Mechanization

The world production of peanuts is 45.9 million tons, of which China and India account for 50% of the total production. The cultivation of peanuts in Italy has had a reduction in recent decades mainly due to the high harvesting costs due to a lack of specific mechanization despite possessing favorable soil and climatic conditions. In this work, modern harvesting technologies are analyzed for adaptation to Italian areas and loss containment, and agronomic technique adaptation for mechanical harvesting. The mechanical harvesting was evaluated in two steps: plant extraction and separation pods. The results showed that lower planting density led to approximately 22% higher production and reduction in crop losses (−52%). The same trend showed that yield and harvesting efficiency were found to be 40% and 22% higher. Our research aimed to evaluate the impact of new technologies integrated by suitable agronomic management, grain losses, and the quality of the final product obtained. The lowest density also improved the healthy pod rate by 11%, from 59 to 70%. These results suggest that an integration of modern technologies and specific agronomic management improves pod retention during harvesting.

Fungi-assisted bio-flocculation of Picochlorum sp.: A novel bio-assisted treatment system for municipal wastewater

Integration of microalgal cultivation with wastewater reclamations are sustainable valorizations approach to nutrients removal and lipid-rich biomass production. Lower growth rates and higher harvesting costs are the major bottlenecks of algal-based wastewater treatment process. Therefore, this study was carried-out to investigate lipid-rich biomass production using wastewater and demonstrate the low-cost biomass harvesting method. Picochlorum sp. BDUG 100241 (PC) was explored in various combinations of untreated raw municipal wastewater (UTMWW) and secondary treated municipal wastewater (STMWW) with a conventional ASN-III medium. The day-night cycles, pH, and aeration were optimized to improve PC biomass production. For harvesting of PC biomass, different concentrations of filamentous fungi Aspergillus niger MTCC 281 (A. niger) and Stropharia sp. ITCC-8422 assisted bioflocculation approach was investigated. In the first phase of optimization, PC showed maximum nutrient removal efficiency and growth in 50 % STMWW +50 % ASN-III. The present results indicated that a 12:12 h day-night cycle and a pH of 7.0 with aeration resulted in the highest nutrient removal efficiency of COD (90.92 %), phosphate (92.26 %) and nitrate (87.20 %). This optimized conditions also improved the biomass production (2.66 g/L), lipid content (44.04 %), photosynthetic and carotenoids (astaxanthin and β-carotene) production. Further, 10 % Stropharia sp. and A. niger granulated pellets signified the bioharvesting of PC biomass with maximum bioflocculation efficiency of 90.15 % and 92.48 %, respectively. The incorporation of bioflocculants, namely Stropharia sp. and A. niger for the harvesting of microalga biomass facilitated the removal of nutrients, enhanced biomass production (4.21 and 4.01 g/L), and augmented lipid content (43.0 % and 47.33 %) respectively.

Flocculation with intermittent dosing for enhanced microalgae harvesting

One of the bottlenecks to the industrialization of algal biofuel is the high cost of harvesting. Flocculation is an efficient technique for algae harvesting, but flocculant consumption results in additional expenses. To lower the overall cost of algae harvesting, it is essential to explore approaches to reduce flocculant usage. In this study, a novel flocculant dosing strategy of intermittent dosing was investigated for enhanced algae harvesting efficiency, with comparisons to traditional one-time dosing, continuous dosing and dual dosing. The impacts of critical operational parameters were examined, and the mechanism was investigated based on floc analysis. The results demonstrated that intermittent dosing can significantly enhance harvesting efficiency. At the optimal operational conditions of 5 s dosing interval, 10 mg/L min−1 dosing speed and 5 min stirring time, the algae harvesting efficiency increased from 71.1 % to 91.3 % compared to one-time dosing when 15 mg/L CPAM was used as a flocculant. According to floc analysis, intermittent dosing tended to form larger and loosely connected flocs, while traditional one-time dosing tended to produce smaller and denser flocs. The different floc growth mechanisms can help to explain how intermittent dosing improved algae flocculation. In addition, intermittent dosing resulted in a higher removal efficiency of dissolved extracellular organic matter and improved algae recultivation. Finally, the cost estimation was performed, and the operational cost was lowered from 32.65 USD ton−1 algae for one-time dosing to 20.64 USD ton−1 algae for intermittent dosing. Through the investigation of this study, the technical, mechanical and economic feasibility of intermittent dosing for enhanced algae harvesting were established.

Agronomic Techniques and Mechanized Harvesting Techniques for Yams Status and Countermeasures

Yams are increasingly recognized for their good health benefits as people increasingly focus on healthy eating and wholesome eating. However, the high cost of yam cultivation and harvesting, as well as the limited level of mechanization, severely restricted the development of the industry. For this deep rhizomatous, brittle, and breakable yam crop, mechanized harvesting is prone to breakage, skin breakage, and low damage rates to the intact crop. In this paper, we have analyzed the characteristics of yam, the current situation of the yam economy in China, the development of mechanized techniques for yam harvesting at home and abroad, and the constraints. In addition, the development of casing yam cultivation techniques and mechanization of harvest is also promising. It mainly introduced plowshare furrow openers, disc furrow openers, spiral furrow openers and chain furrow openers, double-row chain yam planting and harvesting machines, spiral yam harvesting and planting machines, fully hydraulically suspended single-row yam harvesters and vibrating yam harvesters.

Productivity and Cost of Post-Tornado Salvage Logging in Upper Coastal Plain of South Carolina, USA

Salvage harvesting is common in the US South following natural disasters such as tornadoes and hurricanes; nevertheless, few studies have evaluated the productivity and costs of these harvests because of their geographic dispersion and the short interval between natural disasters and salvage harvesting. An Enhanced Fujita Scale 3 (EF3) tornado with winds in excess of 250 km per hour struck Aiken County, South Carolina in April of 2020, uprooting trees and severing other stems above breast height. The goal of this study was to estimate the productivity and cost of salvage harvesting in loblolly pine (Pinus taeda L.) stands following severe tornado damage. Salvage harvests were conducted with a rubber-tired drive-to-tree feller-buncher, grapple skidder, tracked loader, and chipper. All stems were chipped and used to produce energy; no roundwood was produced from the harvests. Elemental time-and-motion studies were conducted in three pulpwood-sized stands (<30 cm large-end diameter) and three sawtimber-sized stands (≥30 cm large-end diameter). Hourly harvesting costs were estimated using the machine rate method and per-ton costs were estimated using a modified version of the Auburn Harvesting Analyzer. Skidding productivity was low in each harvest unit, but especially so in the three pulpwood-sized stands because of stem breakage and low weight per stem. Harvesting costs averaged $29.78 and $19.97 (USD) per tonne (onboard truck) in the pulpwood- and sawtimber-sized stands, respectively. High salvage harvesting costs mean that landowners can expect significantly reduced stumpage prices from these harvests; nonetheless, landowners do benefit from reduced reforestation costs. Harvesting promptly after a tornado can reduce harvesting costs and increase timber value recovery.

Phosphorus recovery from wastewater using extracellular polymeric substances (EPS)-like hydrogels

Phosphorus (P) recovery from wastewater is meaningful in wastewater treatment and resource recycling. Natural extracellular polymeric substances (EPS) of microbes show impressive P uptake ability. However, natural EPS is difficult to assist in P recovery due to the high harvesting cost in extraction. Thus, EPS-like hydrogels constructed by sodium alginate (SA)-Fe(III) and humic acids(HA) were designed. The results showed that the optimal formation conditions of EPS-like hydrogel were 0.1 M Fe(III) and m(HA):m(SA) = 1. Fe(III) ions were the key crosslinkers in constructing the 3-dimensional sodium alginate (SA)-Fe(III) hydrogels and in the embedding of humic acid (HA) for HA@SA-Fe(III) hydrogels. HA@SA-Fe(III) hydrogels showed bigger pore sizes, lesser Fe leaching, and higher phosphate selectivity in SO42− compared to SA-Fe(III) hydrogels. The highest P adsorption amounts were 56 and 134.33 mg-P/g for the HA@SA-Fe(III) and SA-Fe(III), respectively. The adsorption isotherm results exhibited that when the initial P concentration was in a range of 0–35 mg/L, the adsorption mainly existed on the surface of the adsorbent. While in the pore-filling stage (i.e., the initial P concentration was higher than 35 mg/L), internal diffusion controlled the adsorption process based on the kinetics. The X-ray photoelectron spectroscopy (XPS) analysis detected an appearance of Fe-O-P and O-P bonds and a disappearance of chloride ions in the hydrogels after adsorption, which confirmed the major driving forces on adsorption (ligand exchange and ion exchange). Moreover, HA@SA-Fe(III) hydrogel saturated by P adsorption passed a test as sustainable-release P fertilizers. Overall, the EPS-like hydrogels developed here provide new absorbents for P recovery.

Investigation of the interactions between tomatoes and handling devices in mechanized processes

Tomatoes are a major vegetable crop worldwide. Production costs for large due to high harvesting costs and difficult mechanization. An increase in labour productivity, the profitability of production, the increase in production and the decrease in cost is possible through the introduction of mechanization of production processes, the most important of which is harvesting [19]. It absorbs over 50% of total costs [5, 10]. Mechanized harvesting reduces labour costs 10 times, and according to Bakulev [1], the profitability of production reaches 200%. Research by the University of California [18] indicates that the price of mechanically harvested tomatoes is $9.84/t, and for hand-harvested tomatoes - $17.19/t. Depending on the qualifications of the workers, mechanization saves from 70 to 440 man-hours per hectare. The mechanization of harvesting also has a biological side [6]. The short period of harvesting allows to control the ripening. Thus, the degree of de-esterification of the pectin content beyond the desired can be avoided. A lot of research has been done to create a robot that picks tomatoes but it is still only in the research field. A practically implemented mechanization of the process is achieved with a tomato harvester that harvests the entire crop at once. Due to the large losses due to damage to the fruit and leakage of juice, this method also needs improvement. In the present study, dependencies have been derived that make it possible to determine the parameters of the handling devices in the tomato harvester in order to obtain a better result from the mechanized harvesting of tomatoes.

A semi-continuous algal-bacterial wastewater treatment process coupled with bioethanol production

Harnessing the biomass energy potential through biofuel production offers new outlets for a circular economy. In this study an integrated system which combine brewery wastewater treatment using algal-bacterial aggregates instead of activated sludge was developed. The use of algal-bacterial aggregates can eliminate the aeration requirements and significantly reduce the high biomass harvesting costs associated with algal monocultures. A sequencing batch reactor (SBR) setup operating with and without biomass recirculation was used to investigate pollutant removal rates, aggregation capacity and microbial community characteristics under a range of hydraulic retention times (HRTs) and solid retention times (SRTs). It was observed that biomass recirculation strategy significantly enhanced aggregation and pollutant removal (i.e., 78.7%, 94.2% and 75.2% for d-COD, TKN, and PO43--P, respectively). The microbial community established was highly diverse consisting of 161 Bacterial Operational Taxonomic Units (B-OTUs) and 16 unicellular Eukaryotic OTUs (E-OTUs). Escalation the optimal conditions (i.e., HRT = 4 d, SRT = 10 d) at pilot-scale resulted in nutrient starvation leading to 38–44% w/w carbohydrate accumulation. The harvested biomass was converted to bioethanol after acid hydrolysis followed by fermentation with Saccharomyces cerevisiae achieving a bioethanol production yield of 0.076 g bioethanol/g biomass. These data suggest that bioethanol production coupled with high-performance wastewater treatment using algal-bacterial aggregates is feasible, albeit less productive concerning bioethanol yields than systems exclusively designed for third and fourth-generation biofuel production.

Operational and Environmental Comparison of Two Felling and Piling Alternatives for Whole Tree Harvesting in Quercus Coppices for Bioenergy Use

Coppices are a major potential source of forest biomass in Spain, where they occupy around 4M ha. Quercus coppices are mostly neglected because of their high harvesting costs and the small size of their products. This makes them very interesting to test and compare alternative means for utilizing their resources in an optimized way. Hence, a comparative study of motor-manual and mechanized felling and bunching was conducted when thinning dense coppice stands of the two most important oak species in Spain to obtain biomass for bioenergy use. In particular, the study matched chainsaw felling and manual piling against the work of a drive-to-tree feller-buncher previously analyzed in the very same sites. Productivity functions for motor-manual felling and piling were fitted for each species. The derived unit cost functions show that the felling-bunching costs are lower for the motor-manual option in stands of both species, particularly for the smaller tree sizes. Nevertheless, when the strongly reduced loading times in forwarding associated to the mechanization are taken into account, the total harvesting cost is often lower for the mechanized option. That is true for all tree sizes of Q. ilex, and for trees larger than 13 cm diameter at breast height (DBH) for Q. pyrenaica. Residual stand damage was low to moderate, but always significantly greater for the mechanized option compared with the motormanual one. Soil damage was very low for both alternatives. The stumps experimented significantly greater damages in the mechanized felling and bunching, but further research is needed to determine if those damages have any impact on stump mortality, sprouting capability and future plants vigor. The greater productivity and level of tree damages found in Q. ilex when compared to Q. pyrenaica are likely due to the narrower and lighter crown of the latter.

Low energy harvesting of hydrophobic microalgae (Tribonema sp.) by electro-flotation without coagulation.

Microalgae have great potential for biofuel production and wastewater treatment, but the high cost of harvesting hinders their practical application. In this study, economical harvesting of hydrophobic microalgae by electro-flotation without coagulation was assessed. The harvesting performance of this method for selected species of freshwater microalgae with different degrees of hydrophobicity (Tribonema sp., highly hydrophobic; Scenedesmus sp., moderately hydrophobic; and Pandorina sp., hydrophilic) were compared. It was found that microalgal hydrophobicity played a critical role in electro-flotation. Under the same condition (current 0.3 A, velocity gradient 200 s-1, biomass concentration 1 g/L), Tribonema sp. could be effectively harvested (96.2 ± 0.4%) after 20 min of electro-flotation, while the harvesting efficiency decreased significantly with Scenedesmus sp. (70.1 ± 5.2%, 20 min) and Pandorina sp. (<10%, 1 h). The influences of current, electrolysis time, mixing intensity (velocity gradient) and biomass concentration on Tribonema sp. (hydrophobic) harvesting were further investigated. Increasing the current within a certain range (0.1 A-0.4 A) was beneficial to harvesting, while it's further increase decreased floating velocity, which was similar to the effect of the velocity gradient. Under the optimal condition, the harvesting efficiency of Tribonema sp. was 96.3% and the energy consumption (0.19 kWh/kg biomass) was much lower than other harvesting techniques, indicating that electro-flotation is a time-saving and economical approach for hydrophobic microalgae harvesting.

Integrated electrocoagulation-flotation of microalgae to produce Mg-laden microalgal biochar for seeding struvite crystallization

Developing sustainable materials for recovering and recycling nutrients from wastewater is critically needed for nutrients such as phosphorus that have a diminishing supply. Struvite crystallization is emerging as a promising strategy for phosphorus recovery which can be enhanced with seeding through microalgal biochar. The main bottleneck of using microalgae is its high harvesting cost. In this study, an integrated electrocoagulation-flotation (ECF) process is used to recover and at the same time modify the algal surface with magnesium anode and inert carbon cathode. Harvesting efficiency of 98% was achieved with 40.78 mA cm−2, 0.5 cm inter-electrode distance and energy consumption of 4.03 kWh kg−1 in 15 min. The harvested microalgae were pyrolyzed to obtain a yield of 52.90% Mg-laden microalgal biochar. Simultaneously, surface impregnation of 28% magnesium was attained as confirmed by Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Phosphorus recovery and struvite yield of 93.70% and 2.66 g L−1, respectively, were obtained from dosing 1.50 g L−1 Mg-laden microalgal biochar. Comparison of physicochemical characteristics of residual supernatant after microalgal harvesting and struvite recovery showed that the combined use of both the residuals can serve as a sustainable growth medium for microalgae. The overall operating cost of the integrated process was found to be 2.48 USD kg−1 with a total energy consumption of 10.76 kWh kg−1, which was found to be lower than conventional harvesting unit processes such as centrifugation and filtration. This novel approach can help attaining a circular bioeconomy by encompassing nutrient recovery and waste management in an integrated process.

Perception of farmers on the impact of lockdown due to Covid-19 on agriculture and oil palm cultivation in the state of Andhra Pradesh, India

A study was conducted to find the impact of lockdown due to the pandemic of coronavirus disease 2019 (COVID-19) on agriculture, in general, and on oil palm cultivation, in specific. Results revealed that the majority of the farmers contacted had 26-30 years of farming experience, were between 31-60 years of age, were educated up to high school level, with an average of four family members and possessed medium landholdings. The crops grown by these farmers include oil palm, maize, coconut, paddy, cocoa and vegetables. The majority of them had irrigated dry lands. All the farmers were aware about the reasons for the lockdown due to the COVID-19 pandemic. Areas where lockdown impact was visible on agriculture, either directly or indirectly, include labour availability, high cost of labour, harvesting, transport, and market prices. Resources affected due to lockdown were labour, fertilizers, harvesting, transport etc. All cultural practices were adopted in oil palm. The majority of the respondents perceived that oil palm was not affected compared to other crops during the lockdown; they opined to have obtained a good market price for oil palm during the lockdown period. Most of them informed that they received oil palm cultivation related messages sent by ICAR-IIOPR, Pedavegi. They perceived to be aware of the technologies during the lockdown period. Messages (SMS) on oil palm irrigation, cultivation practices, and fertigation were adopted. The need for Government assistance during the lockdown period was felt in the following aspects for different crops, viz., marketing, cultivation assistance, and transport. Farmers perceived that lockdown might have long-term implications due to the non-availability of labour for harvesting crops. It is evident from the study that crops affected severely during the lockdown period require long term strategies to mitigate the problems faced. Farmers must be supported with minimum support price (MSP), transport facilities and ad hoc strategies to sell their products through the government purchase mechanism. A need for monitoring the increase in the prices of agricultural inputs was also felt.

Advances in the co-culture of microalgae with other microorganisms and applications

Intense utilization and mining of fossil fuels for energy production have resulted in environmental pollution and climate change. Compared to fossil fuels, microalgae is considered as a promising candidate for biodiesel production due to its fast growth rate, high lipid content and no occupying arable land. However, monocultural microalgae bear high cost of harvesting, and are prone to contamination, making them incompetent compared with traditional renewable energy sources. Co-culture system induces self-flocculation, which may reduce the cost of microalgae harvesting and the possibility of contamination. In addition, the productivity of lipid and high-value by-products are higher in co-culture system. Therefore, co-culture system represents an economic, energy saving, and efficient technology. This review aims to highlight the advances in the co-culture system, including the mechanisms of interactions between microalgae and other microorganisms, the factors affecting the lipid production of co-culture, and the potential applications of co-culture system. Finally, the prospects and challenges to algal co-culture systems were also discussed.

Effect of photoperiods and CO2 concentrations on the cultivation of carbohydrate-rich P. kessleri microalgae for the sustainable production of bioethanol

Biofuels production from microalgal biomass has been investigated as an alternative approach to replace conventional fossil fuels, contributing to the reduction of greenhouse gas emissions. However, several constraints such as high cultivation and harvesting costs are still limiting the techno-economic viability of microalgae-based biofuels. The integration of wastewater and CO2 streams shows strong potential for lowering the process costs as well as the environmental impacts of conventional microalgal culture systems.In this study, 25 microalgae strains were individually screened for their ability to survive and grow under various CO2 concentrations ranging from 0.04% to 100%. After selecting the most resistant strain, cultivation assays were performed in 3.5 L bubble columns reactors to investigate the effect of different light/dark cycles (4 h/20 h, 12 h/12 h and 20 h/4 h) and CO2 concentrations (0.04%, 2.5%, 5.0% and 10%) on the algal growth properties, the CO2 fixation efficiency as well as the microalgal biochemical composition.The cultivation of Parachlorella kessleri microalgae in the presence of 2.5% (v/v) of pig manure combined with 5% CO2 and light/dark cycle of 20 h/4 h generated the highest specific growth rate (0.58 d−1), biomass productivity (104 mg/L/d) and CO2 fixation rate (211 mgCO2/L/d). These culture conditions triggered the accumulation of carbohydrates in P. kessleri microalgae, resulting in the highest carbohydrate content and productivity of 44.2% and 46.1 mg/L/d, respectively. Subsequently, the carbohydrate-rich microalgal biomass was successfully used as feedstock to produce bioethanol using Saccharomyces cerevisiae yeasts.

Sustainable microalgal biomass valorization to bioenergy: Key challenges and future perspectives

The global trend is shifting toward circular economy systems. It is a sustainable environmental approach that sustains economic growth from the use of resources while minimizing environmental impacts. The multiple industrial use of microalgal biomass has received great attention due to its high content of essential nutrients and elements. Nevertheless, low biomass productivity, unbalanced carbon to nitrogen (C/N) ratio, resistant cellular constituents, and the high cost of microalgal harvesting represent the major obstacles for valorization of algal biomass. In recent years, microalgae biomass has been a candidate as a potential feedstock for different bioenergy generation processes with simultaneous treating wastewater and CO2 capture. An overview of the appealing features and needed advancements is urgently essential for microalgae-derived bioenergy generation. The present review provides a timely outlook and evaluation of biomethane production from microalgal biomass and related challenges. Moreover, the biogas recovery potential from microalgal biomass through different pretreatments and synergistic anaerobic co-digestion (AcoD) with other biowastes are evaluated. In addition, the removal of micropollutants and heavy metals by microalgal cells via adsorption and bioaccumulation in their biomass is discussed. Herein, a comprehensive review is presented about a successive high-throughput for anaerobic digestion (AD) of the microalgal biomass in order to achieve for sustainable energy source. Lastly, the valorization of the digestate from AD of microalgae for agricultural reuse is highlighted.

Application of filamentous fungi in microalgae-based wastewater remediation for biomass harvesting and utilization: From mechanisms to practical application

The model of microalgae-based wastewater remediation for nutrient recovery and biomass production has been intensively studied, but high cost of biomass harvesting jeopardizes the industrial application of this model. To support the implementation of this model and the sustainable development, this work introduces the use of filamentous fungi in microalgae-based wastewater remediation for biomass harvesting and utilization. First, this work describes the research progresses of co-cultivation of fungi and microalgae and fungi-assisted algae harvesting. Second, mechanisms and key parameters of fungi-assisted microalgae harvesting are discussed. Third, an in-depth discussion of co-cultivating filamentous fungi and microalgae in wastewater for nutrient removal and biomass collection is provided. Fourth, this work introduces some high-value components, which are of importance to the economic benefits and industrial application of harvested algal-fungal biomass, in microalgae and filamentous fungi. By the end of this paper, some problems associated with the co-cultivation of algal-fungal consortia in wastewater and fungi-assisted microalgae harvesting are listed and potential solutions to these problems are proposed. It is expected that this work can help readers understand the achievements in the research of fungi-assisted microalgae and the importance of this novel model to biomass harvesting and utilization.

Study of The Behavioral Aspects Related to The Production and Marketing of Balady Lime Among Farmers at some Villages of El-Tahrier District at El-Beheira Governorate

This research is mainly aimed to study the behavioral aspects related to the production and marketing of Balady Lime among farmers at some villages of El-Tahrier District, El-Beheira Governorate, The data were collected using a questionnaire with a personal interview, of 158 respondents' farmers which were randomly selected from the farmers growing Balady Lime at the village of Al-Maraka, El-Tahrier District, and represent about 14% of total holders, during the months of November and December 2020. The data were downloaded and scheduled, using statistical methods such as percentages, means, standard deviation, Pearson's simple correlation coefficient and frequency distribution tables were used to explain and interpret the results. The most important findings of the research showed that: - (32.2%) of the respondents had a lack of knowledge level ranging between low and medium according to the technical recommendations concerned with the production and marketing of the Balady Lime, while (54.4%) of them had a low and moderate level of total implementation of the technical recommendations concerned with the production and marketing of the Balady Lime. - A progressive and significant correlation between the respondents' knowledge level as a first dependent variable and (Age, area of ​​agricultural land, Balady Lime grown area, years of experience in Balady Lime farming), and the degree of the respondents' implementation to the technical recommendations concerned with the production and marketing of the Balady Lime as a second dependent variable and (Age, area of ​​agricultural land, Balady Lime grown area, years of experience in Balady Lime farming). - The most important problems facing the Balady Lime respondents farmers was the high prices of agricultural inputs, the spread of Gummosis disease, the dangerous and rapid spread of various insect, fungal and viral pests, the high costs of treatment disease and insect injuries, the low price of the crop, the control by traders of supply prices, the high cost of harvesting and the lack of availability of manufacturing.

Some implications of natural increase of pH in microalgae cultivation and harvest by autoflocculation

Microalgae hold great potential for producing purified high-value products (e.g. pigments and polyunsaturated fatty acids) and represent a source of bioavailable nutrients in aquaculture feeds; however, its production is limited by the high costs of harvesting. Recently, microalgae autoflocculation has been considered a useful solution due to the easy recovery of cell aggregates and natural increase in pH that prevents cell lysis. This work evaluates some cultivation conditions that could contribute to autoflocculation, such as natural pH increase and precipitate formation over the productivity and flocculation of 16 microalgae consortia. Results showed a biomass production of 1.4 to 4.4 dry weight (g L-1) and high flocculation of 81 to ~100%, probably due to Ca3(PO4)2 formation. Moreover, the alkaline pH could have facilitated the assimilation of CO2 and explained the increase of inorganic carbon in the solution obtained. Likewise, results showed a marked descent in electrical conductivity (EC) in solution and high mineral content in the biomass (21.4-35.9%). Finally, this study suggests that the studied culture conditions facilitated microalgae harvest, and the resulting biomass could be a source of bioavailable dietary minerals. Therefore, some of these results might be addressed in future studies with individual microalgae species.

Self-Flocculation as an Efficient Method to Harvest Microalgae: A Mini-Review

The development of clean and renewable biofuels has been of wide concern on the topic of energy and environmental issues. As a kind of biomass energy with great application prospects, microalgae have many advantages and are used in the fields of environmental protection and biofuels as well as food or feed production for humans and animals. However, the high cost of microalgae harvesting is the main bottleneck of industrial production on a large scale. Self-flocculation is a cost-efficient and promising method for harvesting microalgal biomass. This article briefly describes the current commonly used technology for microalgae harvesting, focusing on the research progress of self-flocculation. This article explores the relative mechanisms and influencing factors of self-flocculation and discusses a proposal for the integration of algae cultivation and harvesting as well as the co-cultivation of algae and bacteria in an effort to provide a reference for microalgae harvesting with high efficiency and low cost.