Guangming Tian

Manure biochar influence upon soil properties, phosphorus distribution and phosphatase activities: A microcosm incubation study

Using manure-derived-biochar as an alternative phosphorus (P) source has bright future prospects to improve soil P status. A 98-day microcosm incubation experiment was set up for two soils which were amended with manure biochar at proportions of 0, 0.5% and 1.5%. Swine manure samples were air-dried and manure biochar was prepared by pyrolysis at 400 °C for 4 h. As determined by P-31 nuclear magnetic resonance ((31)P NMR) spectroscopy, manure biochar mainly increased the contents and fractions of orthophosphate and pyrophosphate in two soils, while decreased those of monoesters (P<0.05). At the end of incubation, 1.5% of manure biochar raised soil pH by 0.5 and 0.6 units, cation exchange capacity by 16.9% and 32.2%, and soil total P by 82.1% and 81.1% for silt loam and clay loam soils, respectively, as compared with those soils without biochar. Simultaneously, 1.5% of manure biochar decreased acid phosphomonoesterase activities by 18.6% and 34.0% for clay loam and silt loam, respectively; while it increased alkaline phosphomonoesterase activities by 28.5% and 95.1% for clay loam and silt loam, respectively. The enhancement of soil P availability after manure biochar addition was firstly due to the orthophosphate and pyrophosphate as the major P species in manure biochar which directly increased contents of soil inorganic P, and also attributed to the decomposition of some organic P like monoesters by enhanced alkaline phosphomonoesterase activities from manure biochar addition.

A review of the identification and detection of heavy metal ions in the environment by voltammetry

Currently, environmental pollution by heavy metals is a global problem. Therefore, it is crucial to develop effective detection techniques to determine the levels of heavy metal contamination in various mediums. Voltammetry is a highly sensitive electrochemical method used for the in situ detection of heavy metal ions. This study investigates the current trends related to electrode modification, developments in materials, and optimization of the experimental parameters. We discuss the sensing performance of four kinds of nanomaterials capable of inorganic modification (metal nanoparticles, metal oxides, carbonaceous nanomaterials, and their nanocomposites). The impact of several important factors, such as the deposition potential and time, buffer solution types, and pH on the sensitivity, reproducibility, stability, and anti-interference ability of the detection process, especially with regard to the co-detection of several heavy metal ions, was reviewed. We noted that in addition to the application of voltammetry to water-related issues, it is suitable for rapid and simple identification and analyses of heavy metals in polluted soil and other mediums. Thus, it is important to conduct additional research on the application of voltammetry to this area.

Ozonation as an advanced oxidant in treatment of bamboo industry wastewater.

The present study employed ozonation process to treat the bamboo industry wastewater (BIWW). The impact of ozone dosage and initial organic concentration on color, COD and TOC removal rates were studied along with characterization of the major organics in raw and treated wastewater. The results suggested the ozone dosage of 3.15 g h(-1) (concentration 52.5 mg L(-1)) was suitable for the treatment. After 25 min ozonation of 1L raw wastewater, the color, COD and TOC removal efficiencies were 95%, 56% and 40%, respectively, with an influent COD concentration of 835 mg L(-1). The ratio of kg O(3) kg(-1) COD at 3.15 g h(-1) was 2.8 (<3), revealing that ozonation was a cost effective process for tertiary treatment of BIWW. Longer oxidization time was required to achieve similar results for raw wastewater with higher COD concentration. The chromatogram from gel permeation chromatography revealed that ozonation resulted in the breakdown of high molecular weight compounds into lower molecular weight components but could not completely mineralize the organic matter. The majority of these compounds were identified in both raw and ozonated samples via GC-MS analysis. In addition to ester derivatives as the main intermediates of ozonation, 1-chloroctadecane, methyl stearate, benzophenone and α-cyperone were identified as the by-products of ozonation.

Aerated swine lagoon wastewater: A promising alternative medium for Botryococcus braunii cultivation in open system

To understand the potential of using swine lagoon wastewater to cultivate Botryococcus braunii for biofuel production, growth characteristics of B. braunii 765 cultivated in aerated swine lagoon wastewater (ASLW) without sterilization and pH adjustment were investigated. The results showed that the alga strain could maintain competitive advantage over the 26-day cultivation. The highest dry biomass of alga grown in ASLW was 0.94 mg L(-1) at day 24, which was 1.73 times that grown in BG11 medium, an artificial medium normally used for B. braunii cultivation. And the algal hydrocarbon content was 23.8%, being more than twice that in BG11 medium. Additionally, after the 26-day cultivation, about 40.8% of TN and 93.3% of TP in ASLW were removed, indicating also good environmental benefits of algal bioremediation.

Nitrogen transformations during co-composting of herbal residues, spent mushrooms, and sludge

Sewage sludge composting is an important environmental measure. The reduction of nitrogen loss is a critical aim of compost maturation, and the addition of spent mushrooms (SMs) and herbal residues (HRs) may be helpful. To evaluate the nitrogen transformations during co-composting of sewage sludge, SMs, and HRs, windrows were constructed in a residual processing plant. Dewatered sewage sludge and sawdust were mixed with SMs and HRs at two proportions on a fresh weight basis, 3:1:1 (sewage sludge:sawdust:SMs or HRs) and 3:1:2 (sewage sludge:sawdust:SMs or HRs). The mixture was then composted for 40 d. Changes in the physicochemical characteristic of sewage sludge during composting were recorded and analyzed. Addition of SMs and HRs accelerated the temperature rise, mediating a quicker composting maturation time compared to control. The addition also resulted in lower nitrogen losses and higher nitrate nitrogen levels in the compost products. Among the windrows, SM and HR addition improved the nitrogen status. The total nitrogen (TN) and nitrogen losses for SM and HR treatments ranged from 22.45 to 24.99 g/kg and from 10.2% to 22.4% over the control values (18.66–21.57 g/kg and 40.5%–64.2%, respectively). The pile with the highest proportion of SMs (3:1:2 (sewage sludge:sawdust:SMs)) had the highest TN level and the lowest nitrogen loss. The germination index (GI) values for all samples at maturity were above 80%, demonstrating optimal maturity. The addition of SMs and HRs augments sewage composting.

Copper distribution in water-dispersible colloids of swine manure and its transport through quartz sand

To demonstrate the potential risks associated with the application of solid agricultural wastes, we investigated Cu distribution in water-dispersible colloids derived from swine manure and its transport through quartz sand. Samples were sequentially centrifuged to obtain five colloid suspensions (<10, <1, <0.45, <0.2, and <0.02 μm) and four colloid subsamples (1-10, 0.45-1, 0.2-0.45, and 0.02-0.2 μm). We observed that 2% of Cu in the swine manure was found in the 0.02-10 μm colloid fractions, while 18% was observed in the <0.02 μm colloid suspension. The highest accumulation of Cu was found in the 0.02-0.2 μm fraction of colloids, in which organic carbon was the major component. The Cu in the 1-10 μm colloid fraction existed in both inorganic compounds and organic associations, whereas it mainly existed as organic complexes in colloids <1 μm (<0.53 μm, specifically). Furthermore, large colloids (1-10 μm) of swine manure were partially filtered out as they passed through the sand particles, and fine colloids facilitated the transport of Cu. The formation of organic complexes was hypothesized to enhance the mobility of Cu. Further research is needed to incorporate our experimental findings into a realistic model of particle mobilization and transport through soil or groundwater aquifers.

Inhibitory effects of Cu (II) on fermentative methane production using bamboo wastewater as substrate.

The toxic effects of Cu (II) present in bamboo industry wastewater (BIWW) upon its anaerobic biodegradability of organic content were investigated. The analysis through the Modified Gompertz model indicated that the optimum chemical oxygen demand (COD) concentration for digestion was 22,780 mg L(-1) with a maximum R(m) (maximum CH(4) production rate) value of 2.8 mL h(-1), corresponding to a specific methanogenic activity (SMA) of 2.38 mL CH(4) g VSS(-1)h(-1). The inhibitory effects of Cu (II) on cumulative methane production depended on its concentration and contact time. Low concentrations (5 mg L(-1)) of Cu (II) showed a stimulating effect on methanogenesis. Methane was not detected when the Cu (II) concentration was increased beyond 300 mg L(-1). The IC(50) value of Cu (II), the Cu (II) concentration that causes a 50% reduction in the cumulative methane production, was 18.32 mg L(-1) (15.9 mg Cu(II) gVSS(-1)).

An Eco-tank system containing microbes and different aquatic plant species for the bioremediation of N,N-dimethylformamide polluted river waters

An Eco-tank system of 10m was designed to simulate the natural river. It consisted of five tanks sequentially connected containing microbes, biofilm carriers and four species of floating aquatic plants. The purification performance of the system for N,N-dimethylformamide (DMF) polluted river water was evaluated by operating in continuous mode. DMF was completely removed in Tanks 1 and 2 at influent DMF concentrations between 75.42 and 161.05mg L-1. The NH4+-N concentration increased in Tank 1, followed by a gradual decrease in Tanks 2-5. Removal of NH4+-N was enhanced by aeration. The average effluent NH4+-N concentration of Tank 5 decreased to a minimum of 0.89mg L-1, corresponding to a decrease of 84.8% when compared with that before aeration. TN concentration did not decrease significantly as expected after inoculation with denitrifying bacteria. The average effluent TN concentration of the system was determined to be 4.58mg L-1, still unable to satisfy the Class V standard for surface water environmental quality. The results of this study demonstrated that the Eco-tank system is an efficient process in removing DMF, TOC, and NH4+-N from DMF polluted river water. However, if possible, alternative technologies should be adopted for controlling the effluent TN concentration.

Enhancement of biomass productivity and nutrients removal from pretreated piggery wastewater by mixotrophic cultivation of Desmodesmus sp. CHX1

AbstractPromoting biomass production of the involved strains simultaneously with efficient nutrients removal from wastewater is realistic significance to ensure successful application of microalgae-based process for wastewater treatment. Enhancement of biomass productivity and nutrients removal by mixotrophic cultivation of Desmodesmus sp. CHX1 was conducted in this study when treating aerated piggery wastewater. The results showed that air-stripping might be an effective option as a pre-treatment to remove ammonia nitrogen from piggery wastewater. Mixotrophic cultivation of microalga-bacteria system significantly promoted algal growth and nutrients removal efficiency with the maximal biomass and lipid productivity being 0.869 g l−1 d−1 and 118.2 mg l−1 d−1 (14.5% of the lipid content), respectively, which were superior to other reported values. Nutrients in the piggery wastewater were also removed efficiently, for example, the removal rates of total nitrogen, ammonia nitrogen and total phosphorus were 87...

Nutrient removal efficiency in a rice-straw denitrifying bioreactor

Rice straw was used as a carbon source in a denitrifying bioreactor, for the removal of nutrients from agricultural drainage. Nutrient removal efficiency was evaluated by: (a) nutrient loading rates (low, medium, and high); (b) hydraulic retention time, and (c) comparison with another carbon source (woodchip). The results show that concentrations of nitrate nitrogen (NO3(-)-N), ammonia nitrogen (NH4(+)-N), total nitrogen (TN), and orthophosphate phosphorus (PO4(3-)-P) in the rice-straw bioreactor effluents were reduced by 53%, 25%, 40%, and 35%, respectively, compared with influents at the medium nutrient loading rate (NO3(-)-N: 10-15 mg N L(-1), NH4(+)-N: 10-15 mg N L(-1), PO4(3-)-P: 1.0-1.5 mg P L(-1)) and long hydraulic retention time (HRT, 24h), with a corresponding denitrification rate (DR) of 0.40 mg N L(-1)h(-1). Moreover, the rice-straw bioreactor showed significantly higher (p<0.05) nutrient removal efficiency than the woodchip bioreactor at the medium nutrient loading rate and 24h HRT.