Treatment of municipal sludge by hydrothermal oxidation process with H2O2.

The recent increase in municipal sludge worldwide has led to a great deal of interest in developing an efficient and environmentally friendly sludge treatment method. In the paper, the treatment of municipal sludge by hydrothermal oxidation (HTO) process with H2O2 as the oxidant was proposed. The impacts of HTO temperature and H2O2 mass fraction on the distribution of products, the moisture content, the migration behaviors of the heavy metals (HMs) of the resulted solid products, the concentration of volatile fatty acids (VFAs) and NH3-N contained in the resulted aqueous phase products and the pH value were investigated. The results indicated that the sludge reduction was achieved by HTO treatment, the increasing H2O2 mass fraction and HTO temperature can significantly improve the dewatering performance of the sludge. The potential toxicity fraction of Pb and Cd contained in the resulted solid residual increased with the increasing HTO severity and the potential toxicity fraction of solid residues was still lower than that of raw material. Acetic acid was the main VFAs produced from HTO treated sludge, and its concentration reached to the maximum value of 2923.41 mg/L at 230 °C under H2O2 mass fraction of 15%. The change in the pH of the resulted aqueous phase products was caused by the competition between the acidic (VFAs or CO2) or alkaline (NH3-N) substances derived from the sludge during HTO process. The HTO process was expected to be an efficient method for municipal sludge treatment due to its mild conditions and high heavy metal safety.

Photosynthetic fluorescence characteristics of six macroalgae species in seaweed beds of Gouqi Island, Zhejiang, China.

The study of photosynthetic fluorescence characteristics of algae is important for the analy-sis of photosynthesis and carbon sequestration of algae. In July 2017, six common species of macroalgae found in Gouqi seaweed beds were collected, including Ulva pertusa, Cladophora stimpsonii, Grateloupia livida, Sargassum thunbergii, Polysiphonia urceolata, and Hizikia fusifarme. In the field, the maximal quantum yieids of photosystem2(Fv/Fm) and rapid curves (RLCs) were mea-sured by using pulse-amplitude modulated fluorometer (Diving-PAM). The results showed that the measured maximal quantum yields of U. pertusa, C. stimpsonii, G. livida, S. thunbergii, P. urceolata, and H. fusiforme were 0.702, 0.704, 0.457, 0.618, 0.421 and 0.567, respectively. The Fv'/Fm' of six species were in order of C. stimpsonii>U. pertusa>S. thunbergii＞H. fusiforme＞G. livida＞P. urceolata. The difference between each species and significant difference was found in U. pertusa, C. stimpsonii, and H. fusiforme. H. fusiforme, S. thunbergii and U. pertusa had higher Pm and α than other species, indicating their higher photosynthetic capacity and better adaptation in higher light condition. However, G. livida had higher α but lower Ik, indicating G. livida had higher photosynthetic capacity in low light condition. In a word, differences of photosynthetic capacity and light intense tolerance between the three phyla of macroalgae were found and we suggested H. fusiforme, S. thunbergii and U. pertusa had stronger photosynthetic capacity and light intense tolerance. Our results could provide theoretical basis for the seaweed bed conservation and carbon sequestration of macroalgae.

[Difference of trophic niche between Sebastiscus marmoratus and Larimichthys polyactis in marine ranching of Ma'an Archipelago, China.] / é©¬éžåˆ—å²›æµ·æ´‹ç‰§åœºè¤è–é²‰å’Œå°é»„é±¼è¥å »ç”Ÿæ€ä½å·®å¼‚.

Marine ranching is an effective way to protect and restore coastal fishery resources. In order to assess the impacts of marine ranching construction on the trophic niches and interspecific competition of Sebastiscus marmoratus and Larimichthys polyactis, we analyzed the relationship between the changes of intraspecies trophic niche and the interspecific competition, based on the carbon and nitrogen stable isotope data of these two species collected from 2013 to 2016. The results showed that the intraspecies trophic niches of both species increased significantly in marine ranching area from 2013 to 2016. The total area of the convex polygon (TA) niche increased from 1.89 to 12.43 for S. marmoratus, and increased from 0.34 and 8.86 for L. polyactis, with the interspecific niche overlap area of these two species increasing from 0.13 to 7.69. The standard elliptic trophic niche increased from 1.11 to 4.94 for S. marmoratus, and from 0.14 to 4.06 for L. polyactis, with the interspecific niche overlap area increasing from 0 to 0.26. Values of the δ13C and δ15N of both species showed a tendency of decreasing with time, with significant changes of δ13C, but non-signi-ficant for δ15N. Dietary overlap between those two species increased from 68.9% to 90.6%.

Volatility and partitioning of Cd and Pb during sewage sludge thermal conversion.

In this paper, the thermal characteristics of sewage sludge and the transformation behavior of Pb and Cd during the thermal conversion process were addressed. The incineration process and pyrolysis process of the sewage sludge were investigated by thermogravimetric analysis. The results indicated that the thermal conversion process of the sewage sludge could be divided into three stages and the presence of oxygen could accelerate the decomposition of the sewage sludge. Furthermore, the effects of thermal conditions on the concentration ratio of Cd and Pb and their species partitioning in the residual char and ash were investigated. For the pyrolysis process, the maximum concentration ratio of Cd reached 41.64% at 500 °C and the lowest one 2.92% at 700 °C. Contrary, the concentration ratio of Pb remained above 93% as the temperature increased. Thus, the suitable temperature for the sewage sludge pyrolysis was below 500 °C. For the incineration process, the incineration temperature had great influence on the concentration ratio of Cd and Pb. When the incineration temperature increased from 700 °C to 900 °C, the concentration ratio of Cd decreased drastically from 99.32% to 10.96%. The maximum concentration ratio for Pb (95.31%) was reached at 800 °C. Besides, the lowest concentration ratio of Cd and Pb were obtained at a residence time of 30 min. The partitioning analyses of the Cd and Pb contained in the ash showed that the residence time had little effect on the partitioning of Cd and Pb, and the residual fractions of Cd and Pb were both above 90%. It was concluded that Cd and Pb were properly stabilized in the ash. Thus, Cd and Pb in the ash were difficult to be released into the environment and to cause secondary pollution.

[Feeding habits of the marbled rockfish Sebastiscus marmoratus in the marine ranching off Ma'an Archipelago, China]. / é©¬éžåˆ—å²›æµ·æ´‹ç‰§åœºè¤è–é²‰çš„æ‘„é£Ÿä¹ æ€§.

Marine ranching is considered as an efficient tool to protect and restore the coastal fishe-ries resource. In order to assess the ecological impacts of the construction of marine ranching on rocky fishes, the feeding habits of Sebastiscus marmoratus collected at the marine ranching area off Ma'an Archipelago were studied using stomach contents analyses and stable isotope analyses. Results showed that S. marmoratus mainly preyed on amphipoda, crabs and cephalopods before the construction of marine ranching. The dominant prey species were Caprella sp., Loligo japonica, Charybdis japonica, Petrolisthes japonicas and Amphiura vadicola. Proportion of crabs in the diet of S. marmoratus increased with the increase of fish size, whereas the proportion of amphipoda decreased. After the construction of marine ranching, S. marmoratus fed mainly on crabs, amphipoda, and fishes. The dominant prey species were C. bimaculata, C. japonica, Caprella sp. and Thryssa kammalensis. Proportions of fishes and crabs in the diet of S. marmoratus increased with the increase of fish size, whereas the proportion of amphipoda increased and then decreased. Results of the stable isotope analyses suggested that S. marmoratus populations in the marine ranching area off Ma'an Archipelago could be divided into three feeding groups based on size variations: <10.0 cm BL, 10.0-14.0 cm BL, and ≥14.0 cm BL. The mean trophic level of S. marmoratus was estimated as 3.40.

[A comparative study of different sampling designs in fish community estimation].

The study of fishery community ecology depends on quality and quantity of data collected from well-designed sampling programs. The optimal sampling design must be cost-efficient, and the sampling results have been recognized as a significant factor affecting resources management. In this paper, the performances of stationary sampling, simple random sampling and stratified random sampling in estimating fish community were compared based on computer simulation by design effect (De), relative error (REE) and relative bias (RB). The results showed that, De of stationary sampling (average De was 3.37) was worse than simple random sampling and stratified random sampling (average De was 0.961). Stratified random sampling performed best among the three designs in terms of De, REE and RB. With the sample size increased, the design effect of stratified random sampling decreased but the precision and accuracy increased.

[Effects of sediment on the early settlement stage of Sargassum horneri on rocky subtidal reefs].

By using sediment trap and suction pump to measure the relative sediment levels across different sites and water depths, and through the in situ measurements of Sargassum horneri density, this paper assessed the relationships between the distribution of S. horneri and the sediment levels and wave exposure on the rocky subtidal platforms around Gouqi Island, China. The laboratory-based experiments were also conducted to test the effects of different sediment levels on the attachment of S. horneri zygote and the survival rate of S. horneri germling after the attachment. S. horneri predominated at the sites with lesser sediment and wave exposure, but less distributed in the sites with high level sediment and wave-exposure. At different water depths, the distribution of S. horneri was negatively correlated with the amount of sediment. A medium dusting (dry mass 10.47 mg x cm(-2), approximate 0.543 mm deep) of sediment on the plate reduced the percentage of S. horneri zygotes attached to the substratum by 4.4%, and a heavy dusting (dry mass 13.96 mg x cm(-2), approximate 0.724 mm deep) of sediment on the plate completely prevented the attachment. One week after the settlement of the zygotes, there were 24% of the germlings still survived when the dry mass sediment coverage was 13.96 mg x cm(-2). However, when the dry mass sediment coverage was up to 34.9 mg x cm(-2) (approximate 1.81 mm deep), 100% of the germlings died. Overall, the distribution of S. horneri was not only related to sediment level, but also restricted by wave exposure to some extent. Sediment level was a critical factor affecting the distribution of S. horneri, particularly at its zygote attachment stage.

[Dietary composition and food competition of six main fish species in rocky reef habitat off Gouqi Island].

Based on the monthly investigation data of fish resources in the rocky reef habitat off Gouqi Island from March 2009 to February 2010, this paper studied the dietary composition of three native fish species (Sebasticus marmoratus, Hexagrammos otakii and Hexagrammos agrammus) and three non-native fish species (Lateolabrax japonica, Nibea albiflora and Larimichthys polyactis). The analysis of gut content indicated that the main prey items of these six dominant fish species were Caprellidae, Gammaridea, juvenile S. marmoratus, Engraulis japonicas and Acetes chinensis and the dietary composition of each of the 6 fish species had obvious seasonal variation. There was an intense food competition between native species H. otakii and H. agrammus in autumn, between non-native species N. albiflora and L. polyactis in summer, between non-native species N. albiflora and native species S. marmoratus in autumn, and between non-native species N. albiflora and native species H. otakii in winter. It was suggested the non-native species N. albiflora was the key species in the food competition among the six dominant fish species in this rocky reef habitat, and thus the feeding behaviors of these six fish species could have definite effects on the resource capacity of juvenile S. marmoratus.

[Fish community structure and its seasonal change in subtidal sandy beach habitat off southern Gouqi Island].

To understand the characteristics of fish community structure in sandy beach habitats of island reef water areas, and to evaluate the potential capacity of these habitats in local fish stock maintenance, fishes were monthly collected with multi-mesh trammel nets in 2009 from the subtidal sandy beach habitat off southern Gouqi Island, taking the adjacent rocky reef habitat as the control. alpha and beta species diversity indices, index of relative importance (IRI), relative catch rate, and dominance curve for abundance and biomass (ABC curve) were adopted to compare the fish species composition, diversity, and community pattern between the two habitats, and multivariate statistical analyses such as non-metric multidimensional scaling (nMDS) and cluster were conducted to discuss the fish assemblage patterns. A total of 63 fish species belonging to 11 orders, 38 families, and 56 genera were collected, of which, 46 fish species were appeared in the two habitats. Due to the appearance of more warm water species in sandy bottom, the fishes in subtidal sandy beach habitat showed much higher richness, and the abundance catch rate (ACR) from May to July was higher than that in rocky reef habitat. In most rest months, the ACR in subtidal sandy beach habitat also showed the similar trend. However, the species richness and diversity in spring and summer were significantly lower in subtidal sandy beach habitat than in rocky reef habitat, because of the high species dominance and low evenness in the sandy beach habitat. Japanese tonguefish (Paraplagusia japonica) was the indicator species in the sandy beach habitat, and dominated in early spring, later summer, autumn, and winter when the fishing pressure was not strong. In sandy bottom, a unique community structure was formed and kept in dynamic, due to the nursery use of sandy beach by Japanese anchovy (Engraulis japonicus) from May to July, the gathering of gray mullet (Mugil cephalus) in most months for feeding, and the large quantity appearance of plotosid catfish (Plotosus anguillaris) in early Autumn, which was quite different from the community structure pattern dominated by reef fishes in rocky-algae habitat. The subtidal sandy bottom off Gouqi Island was serving as both nursery and feeding grounds for many fish species, being a suitable habitat for flatfishes. It was concluded that the sandy beaches around Gouqi Island could be a very important habitat for economic fish species, especially as a nursery ground for juvenile fishes, contributing to the fish stock maintenance in specific area.

H2 production from fowl manure by low temperature catalytic gasification.

In the paper, H(2) rich gas produced from fowl manure (hen compost-HC) by low temperature catalytic gasification (LTCG) technology is addressed. The pyrolysis behaviors of the samples before and after weak acid pretreatment were investigated using thermal gravimetric analysis. Furthermore, the catalytic influence of HC char and HC ash on the decomposition of the nascent volatiles was determined. A catalytic role of the minerals contained in HC on its pyrolysis behavior was confirmed due to the high content of Ca. LTCG process promotes the complete decomposition of the manure volatiles and significantly increases H(2) yield and the total gas yield. An obvious catalytic effect of HC char and HC ash on the decomposition of the nascent volatiles is attributed to CaO contained in them.

Preparation and characterization of bio-oils from internally circulating fluidized-bed pyrolyses of municipal, livestock, and wood waste.

Fast pyrolyses of sewage sludge (SS), pig compost (PC), and wood chip (WC) were investigated in an internally circulating fluidized-bed to evaluate bio-oil production. The pyrolyses were performed at 500 °C and the bio-oil yields from SS, PC, and WC were 45.2%, 44.4%, and 39.7% (dried and ash-free basis), respectively. The bio-oils were analyzed with an elemental analyzer, Karl-Fischer moisture titrator, bomb calorimeter, Fourier transformation infrared spectrometer, gel permeation chromatograph, and gas chromatography/mass spectrometry. The results show that the bio-oil from SS is rich in aliphatic and organonitrogen species, while the bio-oil from PC exhibits higher caloric value due to its higher carbon content and lower oxygen content in comparison with that from SS. The bio-oils from SS and PC have similar chemical composition of organonitrogen species. Most of the compounds detected in the bio-oil from WC are organooxygen species. Because of its high oxygen content, low H/C ratio, and caloric value, the bio-oil from WC is unfeasible for use as fuel feedstock, but possible for use as chemical feedstock.

Low temperature catalytic gasification of pig compost to produce H2 rich gas.

The low temperature catalytic gasification of pig compost before and after acid washing was carried out to produce H2 rich gas using a two-stage fixed-bed reactor. Little effect of the minerals on the manure pyrolysis is determined. Under the presence of Ni/Al2O3 catalyst nearly all the tarry matters were cracked into H2, CO, CO2 and residual carbon. High H2 and CO yields were obtained by low temperature catalytic steam gasification. Acid washing results in the decrease in the content of the ease-hydrolyzed organic components, which volatilize at low temperature. The change in the gas yields from the manure during catalytic decomposition is in accordance with its pyrolysis behavior.

Effect of pretreatment with different washing methods on the reactivity of manure char.

During low temperature gasification process of livestock manure, combustion of manure char feedbacks energy for the gasification reactions. The purpose of the present study is to determine the effect of mineral matters on the reactivity of manure char. The chars were prepared from pig and hen composts pretreated by different washing methods. The results show that the oxidation behavior of the manure char is affected greatly by the pretreatment process employed. Oxidation reactivity of the char from raw manure is much higher than that from de-mineralized manure sample. A good correlation between char reactivity and ash content was obtained. The difference in the char reactivities should be attributed to the presence of catalytically active inorganic constituents, especially Ca species.

Influence of manure types and pyrolysis conditions on the oxidation behavior of manure char.

Livestock manure can be quickly converted into valuable products (H(2), syn-gas and char) by low temperature gasification. Manure char combustion offers energy for the gasification reactions. In the paper, the influence of manure type and pyrolysis conditions on manure char reactivity is addressed. The results show that the oxidation behaviors of manure char are dependent strongly on manure type and pyrolysis conditions employed. The large difference between the oxidation behaviors of pig and hen manure chars can be attributed to the difference in the organic materials and minerals of the samples. High final temperature, flash pyrolysis and water steam atmosphere used for char preparation promote the resultant char reactivity.

[Distribution characteristics of benthic algae in intertidal zone of Ma' an Archipelago of Zhejiang Province].

Based on the survey of benthic algae in the intertidal zone of Ma' an Archipelago from March to July 2007, the algal species composition, distribution, and temperature feature were studied. The dominant algal species in the study area were preliminarily analyzed by using similarity indices (S(c)) and index of relative importance (IRI(c)). A total of 31 species sampled in sublittoral area were identified, among which, 7 species of 5 genera belonged to Chlorophyta, 8 species of 5 genera belonged to Phaeophyta, and 16 species of 14 genera belonged to Rhodophyta. Topical and selective distribution species influenced by wave and tide were identified in the intertidal zone. Ulva pertusa and Sargassum thunbergii were found in all survey area. Rhodophyta was the dominant species, with the occurring frequency being up to 61.1%, and Chlorophyta showed quite uniformed horizontal distribution. In addition, 81% of sampled species were from low-tide zone, and some were extended from mid-tide zone to low-tide zone. The composition comparability between mid-tide and low-tide species was 0.47, and the convergence effect in mid-tide and low-tide zone was higher than that in high-tide and mid-tide zone. The sublittoral area of Ma' an Archipelago showed obvious vertical zoning character, with temperate species being absolute abundant, and the warm-water species dominant. The marine floral texture of Ma' an Archipelago belongs to warm temperate-subtropical transitional marine flora.

[Research progress on seaweed bed ecosystem and its engineering].

Seaweed bed ecosystem is one of the typical nearshore ecosystems. Because of its unique structure and function, the ecology and engineering of this ecosystem have received much attention around the world in recent years. In this paper, the concept, structure, and function of seaweed bed ecosystem, as well as the definition and implementing steps of seaweed bed ecosystem engineering were introduced, and the most recent development in the research of seaweed bed ecosystem in developed countries was reviewed, with the research projects in the United States and Japan as examples. More basic research in seaweed bed ecosystems in China was urgent to be conducted to promote the marine economy and the development of relevant sciences and technologies.