Environmental impacts of cement kiln co-incineration sewage sludge biodried products in a scale-up trial.

The biodrying technology as a pretreatment technology can overcome the limitations of cement kilns co-incineration sewage sludge (SS) on energy consumption. But the impact of SS biodried products on cement kilns and the route carbon reduction potential of biodrying + cement kilns have not been studied. In this study, SS biodrying and cement kiln co-incineration biodried product trials were conducted to highlight the matrix combustion characteristics, and the impact of biodried products on cement kilns (clinker capacity, coal consumption, and pollutant discharge). The carbon emissions of the four scenarios were assessed based on these results. The results showed that water removal rate reached 65.5 % after 11-day biodrying, and the wet-based lower heating value of the biodried product increased by 76.0 % compared with the initial matrix. Comprehensive combustibility index of the biodried product (0.745 × 10-7 %2℃-3min-2) was better than that of SS (0.433 × 10-7 %2℃-3min-2) although a portion of the organic matter was degraded. Cement kiln co-incineration of biodried products (150 t/d) resulted in per tonne of clinker saved 5.61 kg of coal due to the heat utilization efficiency of biodried products reached to 93.7 %. However, it led to an increase in the emission concentrations of NOX and SO2. Assessment results indicated that the biodrying + cement kiln pathway reduced CO2 emissions by 385.7 kg/t SS. Biodried products have greater potential to reduce emissions as alternative fuels than as fertilizers. This study indicated the advantages of SS biodrying + cement kiln co-incineration route.

Comprehensively assessing priority odorants emitted from swine slurry combining nontarget screening with olfactory threshold prediction.

The lack of one-to-one olfactory thresholds (OTs) poses an obstacle to the comprehensive assessment of priority odorants emitted from swine slurry using mass spectrometric nontarget screening. This study screened out highly performing quantitative structure-activity relationship (QSAR) models of OT prediction to complement nontarget screening in olfactory perception evaluation. A total of 27 compounds emitted at different slurry removal frequencies were identified and quantified using gas chromatography-mass spectrometry (GC-MS), including thiirane, dimethyl trisulfide (DMTS), and dimethyl tetrasulfide (DMQS) without OT records. Ridge regression (RR, R2 = 0.77, RMSE = 0.93, MAE = 0.73) and random forest regression (RFR, R2 = 0.76, RMSE = 0.97, MAE = 0.69) rather than the commonly used principal component regression (PCR) and partial least squares regression (PLSR) were used to assign OTs and assess the contributions of emerging volatile sulfur compounds (VSCs) to the sum of odor activity value (SOAV). Priority odorants were p-cresol (25.0-58.9 %) > valeric acid (8.3-31.7 %) > isovaleric acid (6.7-19.0 %) > dimethyl disulfide (4.7-15.7 %) > methanethiol (0-13.6 %) > isobutyric acid (0-8.6 %), whereas the contributions of three emerging VSCs were below 10 %. Vital olfactory active structures were identified by QSAR models as having high molecular polarity, high hydrophilicity, high charge quantity, flexible structure, high reactivity, and a high number of sulfur atoms. This protocol can be further extended to evaluate odor pollution levels for distinct odor sources and guide the development of pertinent deodorization technologies.

Influence of microbial community succession on biodegradation of municipal sludge during biodrying coupled with photocatalysis.

A 20-day sludge biodrying process was coupled with photocatalysis to improve biodrying efficiency and investigate the effect of photocatalysis on biodegradation. After biodrying, the moisture content in the coupled photocatalytic group (TCA) and the control group (TUCA) decreased from 63.61% to 50.82% and 52.94%, respectively, and the volatile solids content decreased from 73.18% to 63.42% and 64.39%, respectively. Neutral proteinase activity decreased by 9.38% and 28.69%, and lipase activity decreased by 6.12% and 26.17%, respectively, indicating that photocatalysis helped maintain neutral proteinase and lipase activities. The Chao1 and Shannon indices showed that photocatalysis increased fungal diversity and reduced bacterial richness and diversity. The ß diversity clustering analysis indicated that the bacterial community structure during the thermophilic phase in TCA differed from that in TUCA. The Kyoto Encyclopedia of Genes and Genomes annotation showed that photocatalysis has the potential to promote the synthesis and degradation of ketone bodies. Biodrying coupled with photocatalysis can improve the dewatering of sludge without negatively affecting biodegradation.

Sludge biodrying coupled with photocatalysis improves the degradation of extracellular polymeric substances.

The efficiency of sludge dewatering is limited by extracellular polymeric substances (EPS) during biodrying. This study investigated the effect of photocatalysis-mediated EPS degradation on sludge dewatering performance during the sludge biodrying process. The photocatalysis of municipal sludge was first carried out to choose a cost-efficient catalyst. Then sludge biodrying tests were performed using TiO2-coated amendment (TCA) and uncoated amendment (TUCA) as the control. Municipal sludge photocatalysis results showed that using TiO2 could efficiently degrade carbohydrates and proteins in the EPS within 60 min. After 20-day biodrying, photocatalysis significantly promoted a reduction in the moisture content and EPS by 17.64% and 6.88%, respectively. The surface-enhanced Raman scattering (SERS) intensities of the C-C-O symmetric stretching vibration peak of D-lactose and the C-S stretching vibration peak of cysteine were significantly decreased by approximately 33.19% and 44.76%, respectively, indicating that photocatalysis indeed promoted the reduction of polysaccharides and cysteine in the EPS, especially after the thermophilic phase. The hydrophilic amino acid content decreased by 23.02%, verifying that photocatalysis could improve EPS hydrophobicity. Consequently, municipal sludge biodrying coupled with photocatalysis promotes sludge EPS degradation and enhances sludge dewaterability, improving the efficiency of sludge biodrying.

Intercropped Amygdalus persica and Pteris vittata applied with additives presents a safe utilization and remediation mode for arsenic-contaminated orchard soil.

Intercropping the arsenic (As) hyperaccumulator Pteris vittata with fruit trees can safely yield peaches in As-polluted orchards in South China. However, the soil As remediation effects and the related mechanisms of P. vittata intercropped with peach trees with additives in the north temperate zone have rarely been reported. A field experiment was conducted to systematically study the intercropping of peach (Amygdalus persica) with P. vittata with three additives [calcium magnesium phosphate (CMP), ammonium dihydrogen phosphate (ADP), and Stevia rebaudiana Bertoni residue (SR)] in a typical As-contaminated peach orchard surrounding a historical gold mine in Pinggu County, Beijing City. The results showed that compared with monoculture (PM) and intercropping without addition (LP), the remediation efficiency of P. vittata intercropping was significantly increased by 100.9 % (CMP) to 293.5 % (ADP). CMP and ADP mainly compete with available As (A-As) adsorbed to the surface of Fe-Al oxide through PO43-, while SR might activate A-As by enhancing dissolved organic carbon (DOC) in P. vittata rhizospheres. The photosynthetic rates (Gs) of intercropped P. vittata were significantly positively correlated with pinna As. The intercropping mode applied with the three additives did not obviously affect fruit quality, and the net profit of the intercropping mode (ADP) reached 415,800 yuan·ha-1·a-1. The As content in peaches was lower than the national standard in the intercropping systems. Comprehensive analysis showed that A. persica intercropped with P. vittata applied with ADP is better than other treatments in improving risk reduction and agricultural sustainability. In this study, a theoretical and practical basis is provided for the safe utilization and remediation of As-contaminated orchard soil in the north temperate zone.

Cadmium accumulation responses in Hylotelephium spectabile: The role of photosynthetic characteristics under different nitrogen, moisture, and light conditions.

The influence of environmental factors on Cd accumulation by Hylotelephium spectabile and its physiological mechanisms are unclear. A field trial was conducted to investigate the effects of nitrogen, soil moisture, and light regulation on plant growth, Cd absorption and translocation, and the photosynthetic characteristics of two H. spectabile populations (LN with high Cd accumulation capacity and HB1 with relatively low Cd accumulation capacity). The results showed that Cd accumulation in LN was 59.6% higher than that in HB1 which may partly be explained by the inherent high transpiration rate of LN, especially at the terminal stage. In addition, the photosynthetic rate of LN responded more positively to nitrogen than HB1, which further amplified its advantages on plant growth and Cd accumulation. Moderate drought significantly stimulated root growth of LN, indicating that LN possesses stronger resistance to drought. Shade inhibited Cd distribution, rather than directly affecting Cd concentrations in H. spectabile. The combined stress of shade and drought had a synergistic effect on Cd translocation in H. spectabile. Moreover, LN achieved 17.3%∼444.5% higher transpiration levels than HB1 under environmental stress, which ensured a more efficient Cd transport capacity of LN. Therefore, the investigation of photosynthetic characteristics further revealed the physiological mechanism by which LN accumulated Cd superior to HB1 under environmental stress and responded more positively to nitrogen nutrition.

Insights into the effect mechanism of back-mixing inoculation on sewage sludge biodrying process: Biodrying characteristics and microbial community succession.

Back mixing was frequently used to replace conventional bulking agenting, however, however, the internal effect mechanism was unclear. This study compared four bulking agents: mushroom residue (MR), MR + primary BM (BM-P), BM-P, and secondary BM (BM-S). The effect mechanism of back mixing (BM) inoculation was assessed based on biodrying performance and microbial community succession. Four trials (Trial A, Trial B, Trial C, and Trial D) reached maximum temperatures of 61.9, 68.8, 73.7, and 69.9 °C on days 6, 3, 2, and 2, respectively. Application of BM increased pile warming rate and resulted in higher temperatures. Temperature changes and microbial competition lead to decline in microbial diversity and richness during the biodrying process. Microbial diversity increased of four biodried products. The number of microorganisms shared by Trial A, Trial B, Trial C, and Trial D were 90, 119, 224, and 300, respectively. The addition of BM improved microbial community stability, and facilitating the initiation of biodrying process. Microbial genera that played an important role in the biodrying process included Ureibacillus, Bacillus, Sphaerobacter, and Tepidimicrobium. Based on these results, it was concluded that BM was efficient method to enhanced the microbial activity and reduced the usage of bulking agent.

Effects of water-soluble chitosan on Hylotelephium spectabile and soybean growth, as well as Cd uptake and phytoextraction efficiency in a co-planting cultivation system.

Intercropping a Cd-accumulator with economically valuable crops is common in slightly or moderately Cd-polluted farmland soils. A field experiment was conducted to evaluate the effects of water-soluble chitosan (WSC) on the growth and Cd uptake of the Cd-accumulator Hylotelephium spectabile and soybean (Glycine max) during a co-cultivation in Cd-contaminated agricultural soil (WSC, 0 and 10 g·m-2). The results indicated that soybean yields were highest in response to the intercropping and WSC treatment. The results from the field trials generally showed that intercropping and WSC treatments significantly decreased Cd concentrations in inedible parts of soybean by 42.9-72.1% (except for stems), in the meantime, increased 95.8%-334.6% in shoot and root tissues of H. spectabile compared with the control (p < 0.05). The data revealed that Cd uptake was highest for H. spectabile during the intercropping and WSC treatment. The application of WSC in the intercropping system significantly increased the uptake of Cd by H. spectabile, but not by soybean. The findings of this study suggest that combining an intercropping system with a WSC treatment may be better for remediating Cd-contaminated soils than other methods involving the growth of a single hyperaccumulator.

This paper clearly focused on the accumulation and uptake of Cd in the system of intercropping of Cd-accumulator (Hylotelephium spectable) and soybean (Glycine max) grown in Cd-polluted farmland soils supplied with water-soluble chitosan (WSC) under field conditions. Some studies mainly focused on active agent to promote remediation efficiency of (hyper) accumulators. This study indicated that combining the intercropping system with WSC may be better for remediating Cd-contaminated soils than the methods involving a single hyperaccumulator.

The impact of land use and land cover changes on the landscape pattern and ecosystem service value in Sanjiangyuan region of the Qinghai-Tibet Plateau.

Decades of intensifying human activities have caused dramatic changes in land use and land cover (LULC) in the ecologically fragile areas of the Qinghai-Tibet Plateau, which have led to significant changes in ecosystem service value (ESV). Taking the ecologically fragile Sanjiangyuan region of the Qinghai-Tibet Plateau as the research object, we focused on understanding the impact of LULC changes on the Sanjiangyuan's landscape pattern and its corresponding ESV, which was combined with a Markov-Plus model to predict LULC changes in 2030. The results showed: (1) from 2000 to 2020, the LULC of Sanjiangyuan has changed to varying degrees, respectively. In the central and southern regions where animal husbandry is the mainstay activity, the area of grass land converted to bareland had expanded; (2) from 2000 to 2010, the total regional ESV increased sharply. However, the total amount of ESV decreased from 2010 to 2020; (3) the overall ESV in the study area was observed to be trending down and is expected to decrease by approximately 4.25 billion CNY by 2030; (4) the fragmentation and complexity of regional landscape patterns will negatively affect local ecosystem stability and biodiversity. Overall, there is a strong temporal and spatial correlation between LULC and ESV. This study will provide a reference for the local government to provide targeted and sustainable land management policies, thereby promoting the improvement of the Qinghai-Tibet Plateau regional ecology value.

[Distribution Characteristics and Risk Assessment of Heavy Metal Pollution in Farmland Soils and Crops in Luancheng, Shijiazhuang City].

In order to explore the distribution characteristics of heavy metal contamination of farmland soil surrounding Luancheng town, Shijiazhuang City, Henan province, the concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in the surface soil and crops were determined and assessed. The principal components were also analyzed for source apportionment. The heavy metal concentrations in crops were further detected, and the non-carcinogenic health risks in the study area were evaluated using the probabilistic risk assessment method, as to provide a theoretical basis for the treatment, prevention, and control of heavy metal pollution in farmland soil in Luancheng. According to the results, ω(Cd), ω(Cr), ω(Cu), ω(Pb), and ω(Zn) in the soils were 0.06-1.08, 22.14-473.47, 12.83-150.74, 10.75-577.72, and 62.23-652.78 mg·kg-1, which exceeded the standard with over-standard rates reaching 1.83%, 1.22%, 0.61%, 0.61%, and 1.22%, respectively. Further, Cd and Pb were transported into crops, in which Cd concentrations exceeded the standard in some corn samples, and Cd and Pb concentrations exceeded the standard in some wheat samples. The total non-carcinogenic health risks (TTHQ) to the human body caused by the consumption of heavy metals in corn grown in the study area were all less than 1, with no obvious negative effects, and TTHQ was higher than 1 in wheat, increasing the likelihood of negative impacts on the human body. With the influence of the distribution of pollution-related enterprises in the industrial zone, heavy metal concentrations were higher in the south, west, and middle directions of the study area. Among them, the study area soil was slightly contaminated by Cd (Level 1). Cd and Hg had a slight potential ecological risk (Level 2), whereas other heavy metals had low potential ecological risk (Level 1). In general, most of the surface cultivated soil was not obviously polluted by heavy metals in the study area. According to the PMF results and survey, we speculated that soil heavy metals mainly came from soil parent material (52.05%), artificial pollution sources (historical sewage irrigation and industrial manufacture) (32.98%), and atmospheric deposition (14.97%). To summarize, the study area should be divided into a priority protection category and safe utilization category. The input of pollution sources should be strictly controlled for the priority protection category, and alternative planting, rotating, and fallow should be implemented for the safe utilization category to reduce the risk of standard-exceeding agricultural products.

Metagenomic analysis reveals the microbial degradation mechanism during kitchen waste biodrying.

Biodrying is a treatment to remove moisture using bio-heat generated during organic degradation. Organic matter degradation and microbial metabolism were studied during the whole kitchen waste biodrying, using metagenomic analysis. After the 25-day biodrying process, carbohydrate, protein and lipid contents decreased by 83.7%, 27.8% and 79.3%, respectively, and their degradation efficiencies increased after the thermophilic phase. Lipase activity exceeded 10 mmol d-1 g-1 throughout biodrying. Cellulase and lipase activities recovered by 2.21% and 5.77%, respectively, after the thermophilic phase, while the protease activity had a maximum increment of 347%. Metabolic analysis revealed that carbohydrate, amino acid and lipid metabolism was possibly inhibited by the high temperature, but the relative abundances of related predicted functions recovered by more than 0.9%, 7% and 11%, respectively, by the end of biodrying. Protein function prediction suggests that ß-oxidation, fatty acid biosynthesis, and the degradation of cellulose and chitin were possibly enhanced during the thermophilic phase. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that leucine, isoleucine and lysine could ultimately degraded to acetyl-CoA. Weissella, Aeribacillus and Bacillus were the genera with the most enriched functional genes during the whole biodrying process. These findings help elucidate the microbial degradation processes during biodrying, which provides further scientific support for improving the application of biodrying products.

Exploring the influence mechanisms of polystyrene-microplastics on sewage sludge composting.

To explore the influence mechanisms of polystyrene-microplastics (PS-MPs) on sewage sludge composting and put forward relevant composting adjustment strategies, a 30-day sewage sludge (SS) composting experiment was conducted by adding 0%, 0.5%, and 1% (w/w) PS-MPs. The addition of PS-MPs reduced compost temperature, microbial biomass carbon (MBC), and the degradation of volatile solids (2.6%-4.8%), and inhibited the activities of key enzymes (ß-glucosidase and alkaline phosphatase) but increased urease activity in the thermophilic phase. Moreover, PS-MPs altered the relative abundance of dominant bacteria and changed the relevance of main enzymes and bacterial communities. Moreover, high levels of PS-MPs inhibited the contribution of dominant bacterial to alkaline phosphatase and ß-glucosidase. Redundancy analysis revealed that PS-MPs affected the composting process mainly through reduced MBC at the mesophilic phase and temperature at the thermophilic phase. Thus, regulating MBC and temperature in specific phases could help overcome the adverse effects of PS-MPs on composting.

Correlation of microbial dynamics to odor production and emission in full-scale sewage sludge composting.

Odor is inevitably produced during sewage sludge composting, and the subsequent pollution hinders the further development of composting technologies. Third-generation high-throughput sequencing was used to analyze microbial community succession, and the correlations between odor and microbial communities were evaluated. Hydrogen sulfide (47.5-87.9 %) and ammonia (9.4-49.9 %) contributed majorly to odor emissions, accounting for 93.7-98.5 % of the emissions. Volatile sulfur compounds were mainly produced in the mesophilic and pre-thermophilic phases (43.0-83.4 %), whereas ammonia was mainly produced in the thermophilic phase (52.1-59.4 %). Microorganisms dominant in the mesophilic and thermophilic phases correlated positively with odor production in the following order: Rhodocyclaceae > Clostridiaceae_1 > Hyphomicrobiaceae > Acidimicrobiales > Family_XI, whereas those dominant in the cooling phase showed negative correlations with odor production in the following order: Bacillus > Sphingobacteriaceae > Pseudomonadaceae > DSSF69 > Chitinophagaceae. The back mixing of mature compost is expected to serve as an economical measure for controlling odor during sewage sludge composting.

Inhibitory Effects of the Addition of KNO3 on Volatile Sulfur Compound Emissions during Sewage Sludge Composting.

Odor released from the sewage sludge composting process often has a negative impact on the sewage sludge treatment facility and becomes a hindrance to promoting compost technology. This study investigated the effect of adding KNO3 on the emissions of volatile sulfur compounds, such as hydrogen sulfide (H2S), dimethyl sulfide (DMS), and carbon disulfide (CS2), during sewage sludge composting and on the physicochemical properties of compost products, such as arylsulfatase activity, available sulfur, total sulfur, moisture content, and germination index. The results showed that the addition of KNO3 could inhibit the emissions of volatile sulfur compounds during composting. KNO3 can also increase the heating rate and peak temperature of the compost pile and reduce the available sulfur loss. The addition of 4% and 8% KNO3 had the best effect on H2S emissions, and it reduced the emissions of H2S during composting by 19.5% and 20.0%, respectively. The addition of 4% KNO3 had the best effect on DMS and CS2 emissions, and it reduced the emissions of DMS and CS2 by 75.8% and 63.0%, respectively. Furthermore, adding 4% KNO3 had the best effect from the perspective of improving the germination index of the compost.

Assessing the quality of the soil around a shale gas development site in a subtropical karst region in southwest China.

The construction of shale gas facilities disturbs large areas of land and affects soil quality and function. In this study, we investigated the properties (including physical, chemical, and microbiological indicators) of soil at three different distances from a shale gas development site (<30 m, 30-50 m, and 50-100 m) in a karst area in 2017 and 2020. Our results showed that the soil water content; available carbon, nitrogen, and phosphorus concentrations; total nitrogen and total phosphorus concentrations; microbial biomass, and enzyme activities increased (P < 0.05) as the distance from the well pad increased, and the total carbon content, pH, electrical conductivity, and some ions (magnesium, sodium, and potassium) decreased with distance from the well pad (P < 0.05). The differences in the soil properties were most noticeable in 2017. The increases in the available nutrients were greater than in the total nutrients. The overall soil quality after the shale gas well pad construction was limited by the microbial biomass and sodium contents. The soil properties recovered most quickly at 30-50 m from the well pad, because of local farmland management practices that improved the soil properties and microbial biomass, and reduced the microbial stress. Therefore, we recommend planting sodium-tolerant crops on the land closest to the well pads, to facilitate restoration of the soil that was disturbed during the construction period.

Water-heat balance characteristics of the sewage sludge bio-drying process in a full-scale bio-drying plant with circulated air.

Sewage sludge bio-drying technology has attracted considerable attention in recent years. In this study, we explored the water-heat balance under two ventilation strategies for the first time in bio-drying plants with circulated air, and examined the influence of air circulation on water removal and heat recovery. We want to obtain the relationships of pile temperature, ventilation, and water removal. Then, it provides support for optimizing the bio-drying process conditions and improving the efficiency through analysis of the water-heat relationship. In the low-ventilation and high-ventilation trials, water removed was mainly on Days 9-12 and 1-4, respectively. Ventilation and pile temperature jointly determine the water removed during the bio-drying process. Water balance indicated that more than 30% of the water was removed under the nonventilated process. More organic matter was degraded to maintain a higher pile temperature under low-ventilation than under high-ventilation, which also led to more radiation heat being lost. High-ventilation trial input less energy (3.36 MJ/kg water removed) but obtained a higher bio-drying index I (7.04) and heat utilization efficiency Qeffic (94.1%). Heat balance showed that lower energy consumption by dry air (Qdryair) was obtained due to circulation air with high temperature. Circulation air also has a higher carried capacity of water vapor but carries more water into the pile due to higher humidity.

Safe utilization of cadmium- and lead-contaminated farmland by cultivating a winter rapeseed/maize rotation compared with two phytoextraction approaches.

Compared with phytoextraction, growing suitable crops may be a more profitable and practical approach for managing contaminated farmland, especially when there are multiple pollutants. In this 5-year field study, the phytoaccumulator Hylotelephium spectabile, the high-biomass species amaranth (Amaranthus hypochondriacus), and a winter rapeseed/maize rotation crop were cultivated on farmland contaminated with cadmium (Cd) and lead (Pb). Over 4 consecutive years, the annual Cd uptake and extraction efficiency of H. spectabile was 117.6 g hm-2 and 2.36%, respectively. The Cd extraction efficiency of amaranth was equivalent to that of H. spectabile because of its high biomass, and it extracted more Pb (660-2210 g hm-2) from the soil than did H. spectabile. However, neither of these species was able to remediate contaminated farmland rapidly and inexpensively, even with enhancing strategies such as variety screening and the addition of fertilizers and a chelating agent. A safe utilization approach to cultivate rapeseed instead of wheat significantly reduced the carcinogenic and noncarcinogenic risks. The concentrations of heavy metals in rapeseed oil were below the limits specified in the Chinese national food standard, and the heavy metal concentrations in the byproducts (rapeseed meal and straw) were below the limits specified in Chinese national standards for organic fertilizer and feed. The cost of safe utilization was one-quarter that of phytoextraction, and the net economic benefit was 33.5%-123.5% higher than that of wheat crops. Therefore, the rapeseed/maize rotation is a profitable and feasible approach for the safe utilization of Cd- and Pb-contaminated farmland on the northern plains of China.

How newly developed shale gas facilities influence soil erosion in a karst region in SW China.

We already know that the construction of shale gas extraction infrastructure exacerbates soil erosion in vulnerable areas. We are not clear however, about whether the completed well pads and pipelines continue to influence soil erosion after the construction is completed. We applied high-resolution remote sensing images and DEM data from 2014 and 2017 and the Revised Universal Soil Loss Equation (RUSLE) model to calculate how the layout of the well pads and pipelines in a shale gas development area affected soil erosion. We used Geodetector to analyze the factors that affected the soil erosion intensity around the well pads. The results showed that about 0.02% and 0.12% of the total erosion in the shale gas development zone was directly caused by the completed well pads and pipelines in 2014 and 2017, respectively. Most of the erosion was related to the completed pipelines. The completed shale gas well pads affected the soil erosion intensity up to 90 and 60 m from the pads in 2014 and 2017, respectively. The soil erosion around the completed pipelines was mainly from the soil surface over the pipeline and had little effect on the surroundings. The main influences on the soil erosion intensity at different distances from the well pads were land use and slope, and the interactions between them. We suggest that, when developing new shale gas extraction facilities, gas pipelines should be arranged in gently sloping areas, and vegetation should be planted on the bare soil over the pipelines to reduce soil erosion.

Life cycle and economic assessment of enhanced ecological floating beds applied water purification.

The ecological floating beds (EFB) are widely used in water quality restoration because of its low cost, high efficiency, and green characteristics. However, there is a potential impact of the EFB on the environment while water purification is not in progress. In this study, the life cycle assessment (LCA) and life cycle cost (LCC) methods were used to evaluate the overall environment of mixed-fill and biofilm enhanced EFB. The results show that the total environmental impact of the mixed-fill ecological floating beds (MEFB) is greater than that of the biofilm ecological floating beds (BEFB). In the raw material acquisition and operational stages, the environmental impact of the MEFB is smaller than that of the BEFB, while the environmental impact of the MEFB during the construction phase is much greater than that of the BEFB. The environmental impact of the construction stage of the MEFB accounts for 98.3% of the environmental impact of the entire life cycle. The operational stage of the MEFB was eco-friendly with regard to eutrophication potential, photochemical oxidation potential, ozone layer depletion potential, human toxicity potential, freshwater aquatic eco-toxicity potential, and terrestrial eco-toxicity potential environmental impact, and these effects of the operational stage of the MEFB account for 45.5% of the total environmental impact. The impact of the BEFB on the environment during raw material acquisition, construction, and operation accounts for 46.7%, 37.7%, and 15.6%, respectively, of the entire life cycle impact. Both two EFB technologies, the capital cost was the main expenditure with LCC, accounting for 60.4% and 52.9% of the MEFB and BEFB, respectively.

Microbial degradation in the co-composting of pig manure and biogas residue using a recyclable cement-based synthetic amendment.

This research investigated a synthetic amendment to improve composting and resource recycling of pig manure and biogas residue. We further examined whether adding a synthetic amendment impacts the microbial ecosystem in the composted materials. Three mixing ratios were used to investigate composting performance: no synthetic amendment (T0), 5% synthetic amendment (T1), and 10% synthetic amendment (T2) (T1 and T2 were measured as a wet weight ratio). There were no significant differences in the fundamental characteristics between composting products in T0 and T1. The moisture content of composting material in T0, T1, and T2 significantly decreased from a baseline of approximately 65% to 35.5%, 37.3%, and 55.9%, respectively. Meanwhile, the germination index significantly increased to 111.6%, 155.6%, and 62.3%, respectively. When an optimal proportion of synthetic amendment was added, T1 showed high degree of humification, lignocellulase activities, and effective biodegradation. Firmicutes, Actinobacteria, Proteobacteria, and Bacteroidetes were the dominant bacteria, while Ascomycota and Basidiomycota were the dominant fungi in all treatment groups. Amino sugar and nucleotide sugar metabolism, glycolysis, starch, and sucrose metabolism were among the primary pathways in predicted functions. The synthetic amendment can generate a mature composting product and can be reused or recycled to conserve resources.