Ecological Engineering System Research Articles

Ecological Engineering System Using Floating Macrophytes for the Treatment of Domestic Wastewaters

Water scarcity is a global issue due to the rapid increase in population and overexploitation of resources, which endures an imbalance between availability and demand of bluewater footprint. As a part of the Sustainable Development Goal (Goal 6: Clean Water and Sanitation), the present study designs an Ecologically Engineered System (EES) in this context. The SDGs goals were developed and had the targets for restoring and maintaining ecosystems to provide water-related services and prevent water scarcity problems. The targets indicate the need to integrate ecosystem values into planning, development processes, and strategies for reducing water scarcity. A semi pilot EES was designed with three tanks setup such as floating macrophytes (water hyacinth tank 1), submerged plants (water thymes tank 2), and emergent plants (water lettuce tank 3). The reactor was operated using domestic wastewater in a continuous mode with a flow rate of 20 l/d. Treatment performance was monitored in terms of COD, nutrients, sulphates, turbidity, etc. The study infers that after several cycles of operation, the system was well-optimized for wastewater treatment. Enhanced COD removal efficiency of 71% was observed in addition to other pollutants. The study hypothesized that EES could be an effective strategy to restore the water bodies.

Analysis on the effect of large-scale compound ecological engineering system on pollution control of the estuary of a lake

Abstract The quality of the water and the water environment in the estuary of a lake directly affect the water quality and ecological functions of the entire lake. Multi-technology systems, which integrate biotechnological analysis of a lake estuary and restoration of the ecological functions of the water in situ, have gradually been adopted for lake management and restoration. The Xielugang Estuary is located north of the Yangcheng Middle Lake and always exhibits a certain degree of eutrophic phenomena. To ensure the safety of the ecological environment in Yangcheng Lake, a multi-level purification and ecological system with ‘intercept precipitation–ecological restoration–coupled biological treatment’ was developed. Water quality monitoring results for the inlet and outlet of different units in the system from October 2020 to May 2021 showed that the system was effective. We also found that the purification capacity of the composite system was high and the system could significantly enhance the reduction of total nitrogen, total phosphorus, potassium permanganate index and total suspended solids. The average removal rates for these components were 41.34, 61.76, 35.21 and 67.21%, respectively, and the removal rate for typical heavy metals (Zn, Cu, Cd, and Pb) was 30.4–48.9%. The composite system substantially improved the water quality of the estuary and the wetland ecological function, demonstrating its effectiveness and significance.

On the high-quality development of “blockchain +” enabled smart tourism

<p>Promoting the integrated application of blockchain technology and smart tourism is conducive to improving the efficiency of smart tourism public service platform and guiding the innovation of tourism public service mode; It is conducive to cultivating the new connotation of smart tourism development and activating the new driving force of tourism development; It is conducive to cultivating new forms of tourism and providing new opportunities for the development and transformation of tourism. Many regions have laid out tourism and smart tourism as demonstration application fields for the deep integration of blockchain and real economy. Its basic orientation is to build blockchain tourism platform, establish multi-party consensus mechanism, build blockchain tourism credit management system, expand application fields and enrich application scenarios. In order to accelerate the high-quality development of tourism enabled by “blockchain + smart tourism”: Firstly, accelerate the research, formulation and introduction of relevant policy implementation plans; secondly, build a smart tourism ecological engineering system supported by blockchain technology; thirdly, try to build a blockchain tourism credit management system to solve the market pain points; fourthly, focus on promoting tourism consumption blockchain points to build a global tourism chain. </p>

Sustainable ecological engineering systems for the treatment of domestic wastewater using emerging, floating and submerged macrophytes

Water scarcity is perceived as a global systemic risk since there is an inexorable rise in water demand. An ecological engineering system mimics a natural ecosystem by balancing the trophic conditions for effective treatment of wastewater in a sequential manner. The present study was designed using emergent, floating and submerged macrophytic plants in a systematic approach. The study was evaluated with several components such as plants (water hyacinth, water lettuce and water thymes), aeration (supply of oxygen), and physical adsorption (activated carbon). Domestic wastewater collected from the local effluent treatment plant was treated individually and by combining all the components. Diverse experimental setups viz., lake sediment (control reactor), aeration, activated carbon blocks, water hyacinth, water lettuce, and water thymes were individually studied. Further the above components were combined, such as lake sediment + aeration + activated carbon blocks with plants like water hyacinth, water lettuce, and water thymes. The study inferred along with phytoremediation, and the external factors enhanced the treatment performances. Water hyacinth documented enhanced chemical oxygen demand removal efficiency of 85.71%, followed by water lettuce (80%), and water thymes (77.14%) along with the plants, both aeration, and activated carbon had stimulated the wastewater treatment. The highest removal efficiency of nitrate (70.23%), phosphate (63.64%), and sulphate (61.16%) were observed in water hyacinth due to its thick roots, and fibrous tissues reported effective treatment. The study hypothesized that these processes could be an effective strategy to restore the lakes and regulate the environmental flow. The study infers that an ecological engineering system symbiotically enables to self-organize the ecosystem within the boundary.

Phosphorus removal in a pilot scale free water surface constructed wetland: hydraulic retention time, seasonality and standing stock evaluation

Constructed wetlands (CWs) are decentralized wastewater treatment systems considered to be green and low cost. They have the potential to effectively remove pollutants and recycle nutrients with plant composting. However, they need large areas to implement them due to the usual high Hydraulic Retention Times (HRT), reaching up to 50 days. The main objective of the present study was to evaluate the influence of HRT (HRT = 3, 7, and 10 days), and seasonality on Total Phosphorus (TP) removal, and standing stock in a pilot scale free water surface CW (FWS CW). Unplanted and planted (Eichhornia crassipes) tanks were evaluated in wet and dry seasons. The FWS CW was set up as a complementary treatment to a secondary level wastewater treatment plant. The system was monitored weekly for ten months, totalizing 29 replicate samplings (n = 58). Planted tanks were harvested every week to keep free space for plant reproduction (∼40%). The mean removal efficiency of TP ranged between 82% and 95% without a significant difference between HRT (pvalue > 0.05). However, when the effects of the sedimentation of the unplanted tanks were disregarded, the lowest HRT (3 days) tank presented the highest standing stock of TP. The wet season presented a significant difference in TP removal results (pvalue < 0.05), associated with higher macrophyte growth rate due to more intense solar irradiation and incorporation of TP by E. crassipes. The results point out advances in P removal and recycling by a low-cost ecological engineering system.

Ecological engineering in pond aquaculture: a review from the whole‐process perspective in China

AbstractPond aquaculture undeniably offers the potential for food production worldwide. In China, 45.83% of aquatic production is currently from pond aquaculture. However, with the continuous expansion of this practice, environmental problems such as a high level of water consumption, aquaculture water deterioration, pollution from effluent and aquatic product quality decline seriously restrict the sustainable development of pond aquaculture. In this review, we summarise the (i) the impacts of pond aquaculture on the environment, (ii) research progress in pond aquaculture ecological engineering, (iii) existing technologies regarding pond aquaculture ecological engineering systems, (iv) effects of applying pond aquaculture ecological engineering and (v) summary and prospects. Moreover, we discuss the merits and drawbacks of each method and technology, and future research priorities are reviewed. With this, an understanding of the role played by ecological engineering in pond aquaculture is provided, as well as guidance for precisely managing aquaculture water and effluent, aquaculture practices, and technological developments. In summary, the pond aquaculture ecological engineering can be managed so as to improve animal welfare and the stability of water treatment systems, reducing the adverse effects on the environment and public health, and enabling the sustainable development of pond aquaculture.

Integrated emergy and economic evaluation of an ecological engineering system for the utilization of Spartina alterniflora

Abstract An integrated emergy and economic evaluation of a 7-step ecological engineering system (7-step EES) located in Jiangsu Province, China was carried out. This 7-step EES was constructed to fully utilize existing S. alterniflora production through a low waste, clean production process and to help control the expansion of this invasive grass. First, the above ground S. alterniflora biomass removed for invasion control is used as the feedstock for the extraction of a bio-mineral liquid and its encapsulation, both of which provide a health supplement to treat gout and angiocardiopathy patients. Next, the residues left after extraction are used as a medium for mushroom cultivation, and then for raising earthworms. Finally, the remaining residues become the main component of a microbe enriched organic fertilizer, which is then returned to the soil. A suite of emergy indices were constructed on multiple temporal and spatial scales to examine the operation of the whole system and its subsystems. The results showed that the temporal sustainability of the 7-step EES was relatively high at different spatial scales, especially at the local scale as indicated by its EISDLS (1.55E+03). Full implementation of the 7-step EES for S. alterniflora currently residing on the coast of China can result in a potential economic output that is greater than 2% of the national GDP, with an economic output/input ratio over 29. In addition, the 7-step EES had an environmental loading ratio lower than that of the regional system. Sensitivity analysis showed that decreasing the cost of the purchased inputs needed to make the capsules is the key problem that needs to be solved to optimize the system, both for its sustainability and economic viability, on all spatial and temporal scales.

Long-term operation with an insight into a newly established green bio-sorption reactor: Can it achieve “1 + 1 > 2”?

An eco-friendly system of green bio-sorption reactor (GBR), constructed by embedding alum sludge-based constructed wetland (AlCW) into a conventional activated sludge process to achieve “1 + 1 > 2”, was evaluated under a long-term operation basis. Insight into the pollutants removal, particularly the role of the AlCW in the GBR, was explored and discussed. The results showed that the GBR could achieve 90% and 95% removal for TN and TP (Stage 4), respectively, under the hydraulic and nitrogen loading rate of 2.07 m3/(m3·d) and 166.2 gN/(m3·d), respectively. Intriguingly, despite the P adsorption, the AlCW enlarged the size of the activated sludge flocs which benefited the simultaneous nitrification and denitrification. Subversively, the embedding AlCW brings about dual-intensification in both capacity and efficiency. In addition, the GBR as an ecological engineering system can be employed closely to residential area in line with its green and pleasing appearance.

Effects of bund crops and insecticide treatments on arthropod diversity and herbivore regulation in tropical rice fields

AbstractEcological engineering using vegetable or flower strips is promoted as a potential pest management strategy in irrigated rice. Farmers in the Philippines often plant rice levees (bunds) with vegetables, particularly string beans (Vigna unguiculata [L.] Walpers) to supplement income, but without considering the potential for pest management. This study examines the effects of planted bunds on rice herbivores and their natural enemies. We compared arthropods in (a) rice fields that had string beans planted on bunds, (b) fields without string beans and without any insecticide applications and (c) fields without string beans but with insecticide treatments (standard practice). Rice yield was similar across all treatments; however, the vegetation strips produced an extra 3.6 kg of fresh string bean pods per metre of bund. There were no apparent increases in major natural enemy groups in fields with string beans compared to fields with conventional bunds. Fields with insecticide treatments had higher damage from leaffolders (Lepidoptera: Pyralidae). The sprayed fields also had lower parasitism of planthopper eggs and fewer predatory dragonflies and damselflies (Odonata). Furthermore, the mortality of planthopper (Delphacidae: Hemiptera) and stemborer (Pyralidae) eggs by parasitoids and predators was density dependent only in the unsprayed fields (with and without string beans). Our results demonstrate that planting string beans on rice bunds improves the productivity of rice farms, but our ecological engineering system did not appreciably affect natural enemy or herbivore abundance; however, chemical insecticides adversely affected pest regulatory ecosystem functions leading to higher pest damage.

Integrated water quality, emergy and economic evaluation of three bioremediation treatment systems for eutrophic water

This study was targeted at finding one or more environmentally efficient, economically feasible and ecologically sustainable bioremediation treatment modes for eutrophic water. Three biological species, i.e. water spinach (Ipomoea aquatica), loach (Misgurus anguillicaudatus) and a pseudomonad (Rhodopseudomonas palustris), were combined in different ways: (A) water spinach–loach–pseudomonad; (B) water spinach–loach; (C) water spinach–pseudomonad, to construct three ecological engineering systems targeted at removing nutrients from the eutrophic water of Taihu Lake, PR China. An integrated water quality, emergy and economic evaluation of the three treatment systems was performed based on the observed changes in biomass, water quality, and other natural and economic inputs and outputs. The three ecological engineering treatment systems showed a different order of efficiency in removing nutrients (treatment A>B>C), produced different environmental loadings at the foreground (treatment B>C>A), background (treatment C=A>B) and whole system scales (treatment C>A>B), and had different economic feasibility (treatment B>A>C). Finally, after taking all direct and indirect environmental and economic impacts into account, treatment A was found to be the best choice at the foreground scale, followed by treatment C and then B, while at the background and whole system scales, treatment B was the best option followed by A and C. In this analysis, emergy evaluation was found to be an ideal ecological integration tool for quantifying both the environmental and economic characteristics of ecological engineering systems and processes at multiple scales, including pollution treatment systems. The complex results of this study obtained by considering water treatment efficiency, emergy indices of sustainability and loading on multiple scales besides economic output/input analysis can inform decision-makers about trade-offs that confront them in the management of eutrophic waters.

Concepts and methods of ecological engineering

Ecological engineering was defined as the practice of joining the economy of society to the environment symbiotically by fitting technological design with ecological self design. The boundary of ecological engineering systems includes the ecosystems that self organize to fit with technology, whereas environmental engineering designs normally stop at the end of the pipe. For example, the coastal marsh wildlife sanctuary at Port Aransas, Texas, developed when municipal wastewaters were released on bare sands. The energy hierarchy concept provides principles for planning spatial and temporal organization that can be sustained. Techniques of ecological engineering are given with examples that include maintaining biodiversity with multiple seeding, experimental mesocosms, enclosed systems with people like Biosphere 2, wetland filtration of heavy metals, overgrowth and climax ecosystems, longitudinal succession, exotics, domestication of ecosystems, closing material cycles, and controlling water with vegetation reflectance.

시스템 생태학적 접근법에 의한 넙치생산의 지속성 평가 -2. 넙치 육상양식산업에 대한 예측-

In Korea, an olive flounder is very popular fish food item. However, due to the increasing human population, the present catches of the olive flounder may not be sufficient to satisfy the present demand. To increase the supply of the olive flounder, aquaculture has been begun. An interest in the aquaculture of the olive flounder has been increased recently because of its characteristics of good growth and high price in the market, However, the productivity of the olive flounder aquaculture depends on economic inputs such as fuels, facilities, and labor. The rapid growths of the olive flounder aquaculture and the concerns about economic and ecological sustainability have focused peoples attention on the aquaculture industry. In this study, an energy systems model was built to simulate the variation of sustainability on the aquaculture of olive flounder, The results of simulation based on calibration data in 1995 show that olive flounder production yield and asset slowly increase to steady state because of the law of supply and demand. The results of simulation based on the variation of oil price show that the more increase the oil price, the more decrease the olive flounder economic yield and asset. Energy sources required for systems determine the sustainability of systems. Conclusionally, the present systems of the olive flounder aquaculture should be transformed to ecological-recycling systems or ecological engineering systems which depend on renewable resources rather than aquaculture systems which depend on fossil fuels, and be harmonized with the fishing fisheries by the sustainable use of renewable resources in the carrying capacity.