Study on Piggery Anaerobic Fermentation Slurry Treated by Anoxic/Oxic Process

[Objective] The aim of this study was to provide a fast, stable and efficient piggery wastewater processing technology. [Method] The start-up process was studied through the experiment of piggery anaerobic fermentation slurry treated by Anoxic/Oxic （A/O） reactor. The process was divided into two stages： at the first stage, dominant micro flora were cultivated in Anoxic and Oxic reaction tanks respectively; at the second stage. Anoxic and Oxic reaction tanks were initiated jointly to gradually enhance water load and continued to cultivate and domesticate microorganisms, and finally the start-up process was completed. [ Result] The results showed that return mixture ratio and return sludge ratio was 2 and 1 respectively when the temperature reached 32 ±2 ℃. However. when aeration rate of Oxic reaction amounted to 0.5 m^3/h, the re- moval rate of COD and NH4^＋ -H were 89.87% and 89.31% respectively through practical operation within 50 days, which indicated that the start- up process through A/O reactor was successful. Conclusion This study can provide a scientific basis and reference for innocuous technique of piggery anaerobic fermentation slurry treatment.

Plant Responses to Carbon Dioxide Releasedfrom Piggery

In the present study, lean-to greenhouses were built by sharing a wall of piggeries. The vents in the wall allowed the air exchange between the piggeries and the greenhouses, so that carbon dioxide(CO_2) could be released from the piggeries to the greenhouses, and oxygen(O_2) could be released from the greenhouses to the piggeries. In the greenhouses, tomato, Chinese cabbage and muskmelon were planted and their quality indices were determined to evaluate their response to elevated CO_2. The results showed that the CO_2 concentration in greenhouse was increased, and under such conditions the yield and quality of all tomato, Chinese cabbage and muskmelon were improved.

Plant Selection of Constructed Wetlands for Treatment of Piggery Wastewater

Piggery wastewater contains high concentrations of organic matter and ammonia nitrogen,and it is difficult to treat it and make the discharged wastewater to meet the standard. Since the treatment of piggery wastewater treated under anaerobic conditions by traditional aerobic methods requires large investment,high running expense and strict management,breeding enterprises could hardly accept the technique. According to the characteristics of piggery wastewater,Pennisetum sp. + Rumex acetosa Linn and Populus + Nerium oleander can be planted in constructed wetlands to treat piggery wastewater,which can improve the treatment effect of piggery wastewater by constructed wetlands,solve the difficulty of wastewater treatment in winter,and bring obvious economic benefit.

Effects of Different Ventilation Modes and Outlet Height on Nursery Piggery Environment

In order to study the effects of ventilation modes and outlet height on the airflow field of a nursery piggery,computational fluid dynamics (CFD) technology was used to simulate the wind speed and temperature of an experimental pig house in the cold northern region.This study was conducted with simulation and a comparative analysis of transverse ventilation,longitudinal ventilation and roof air intake modes.Furthermore,the effects of the air outlet height of 0.7,0.6 and 0.5 m with the roof air inlet mode on the environment in the pig house were studied.Field experiments verified the model of roof air intake model.The results showed inadequate ventilation in both the vertical and horizontal ventilation.However,the airfield gradients were less variable and more balanced when using the rooftop air intake mode.The variation of outlet height significantly affected nursery pig houses’ airflow velocity and temperature.Roof air inlet mode with an outlet height of 0.7 m was better than the other two.The normalized mean square error (NMSE) of air velocity and temperature was less than 0.01,and the simulation analysis could genuinely reflect the distribution of the airflow field in the nursery.

Monitoring of Sewage Discharging in Piggery

The rapid development of large-scale livestock and poultry breeding industry causes a large number of slurry and waste, which bdngs great pressure on the surrounding environment and has become an important factor for environmental pollution. To further ascertain the pollution emissions of livestock and poultry breeding industry, protect people＇s health and successfully complete the first national census of pollution sources, a large-scale piggery and a breeding field were selected for monitoring. The results revealed that monitoring indicators in pollution sources of livestock and poultry breeding industry showed significantly positive correlation with breeding size and nutritional level, but negative correlation with animal breeding age. Monitoring indicators in summer and autumn were higher than those in spring and winter, and monitoring indicators of sewage in the piggery reduced significantly through sedimentation process.

Evaluation of Methane Yield on Mesophilic-Dry Anaerobic Digestion of Piggery Manure Mixed with Chaff for Agricultural Area

A mesophilic-dry anaerobic digestion process is valid in treating high-concentration substrates containing low moisture content. It has merits of lower wastewater discharge and lower heat capacity required in maintaining reactor temperature as compared with a thermophilic-wet anaerobic digestion process. In fact, chaff can be easily obtained in farming areas and used as a mixture substrate as one of bulking agents for controlling moisture and supplying carbon. For this reason, this study applies the chaff to improve livestock manure, which contains high moisture content and is discharged from domestic pig farms. This study aims at verifying its feasibility for improving methane production efficiency on a basis of BMP (Biochemical Methane Potential) assay obtained through a series of experiments. Finding results were methane gas production and gas production per volatile solid (VS) added, and methane gas production among biogas production were increased as the chaff added in the piggery manure was increased. According to experimental results for improving the methane production efficiency, mixture of the chaff and the piggery manure played an important role in controlling the moisture content and improving the methane gas production rate, and also verified its feasibility in the mesophilic-dry anaerobic digestion process indicating relatively less difficulty for operation and management.

Structure Design of Large-scale Fattening Pig House with Fermentation Bed

The fattening pig house with fermentation bed had an area of 2 100 m2, and the area of fermentation bed was 1 900 m2 with a utilization rate of 91.4%, which was 45% higher than that of conventional pig house with surrounding barrier. There was feeding trough around the house. The water troughs were set in the middle of the fermentation bed and of the feeding trough on the short sides of the house, separating feed and water. There were electric aluminum alloy shutters in both long sides of the house for ventilation, cooling and heat preservation. On both short sides, there were fans and wet curtains. The spray cooling devices were in- stalled outside the roof for cooling. The environmental control in the piggery, includ- ing light, temperature, water, humidity, carbon dioxide and ammonia, was realized to run by computer automatically. The coconut chaff and chaff configuration were used as mattress material, realizing the advantages of fermentation bed, such as no smell, zero emission, high-quality meat, saving labor, controlling disease, no drug residue, producing fertilizer, intelligent control, mechanized operation, etc.

生态沟渠中盘培牧草对养猪场废水降污效果研究

浙江省杭嘉湖区域水网沟渠发达,是浙江省最大的粮食产区,化肥施用量较高,农业污染日渐严重。本研究采用不另外占用土地的、以盘培多花黑麦草和高羊茅牧草为主要内容的生态沟渠湿地来降解养猪场废水,并分析各项污染物指标在沟渠中的迁移变化。结果表明:多花黑麦草对养猪场废水中的总N、总P的降污能力都要强于高羊茅,对于沟渠水体中的增氧能力则弱于高羊茅。在铺设盘培牧草的600 m沟渠中,各种污染物指标在靠近污水入口处的300 m沟渠内降解速度较快,而在远离污水入口处的后300 m沟渠内变化幅度相对比较平缓。

Biomass Accumulation and Water Purification of Water Spinach Planted on Water Surface by Floating Beds for Treating Biogas Slurry

To find a new way treating the wastewater from biogas reactors in a pig farm, vegetated floating bed was built for observing the water-purifying capability of water spinach (Ipomoea aquatic) planted on the water surface. Experiments were carried out to record the growth and biomass accumulation of water spinach and its effect on purification of biogas wastewater. The results show that the water which mixed with biogas wastewater has been purified significantly by water spinach on the floating bed. During its growth season within four months, the overall length of water spinach reached 199 ± 35 cm, while its root length reached 63 ± 28.6 cm. The average weight of individual fresh plant is of 1285 ± 619.7 g. Meanwhile, the concentration of total nitrogen (TN) in water under the floating bed decreased from 8.9 ± 0.062 mg·L-1 to 0.5 ± 0.011 mg·L-1;the concentration of total phosphorus (TP) decreased from 4.4 ± 0.236 mg·L-1 to 0.92 ± 0.024 mg·L-1;the concentration of chemical oxygen demand (COD) decreased from 87.3 ± 6.68 mg·L-1 to 0.74 ± 0.46 mg·L-1. It suggests that the water spinach removed more than 90% of pollutants in terms of TN, TP, and COD from the water. Results show that the vegetated floating bed technique is a feasible way to dispose the biogas slurry.

Assessment of NH3 Reduction and N2O Production during Treatment of Exhausted Air from Fattening Pigs Building by a Commercial Scrubber

The use of air scrubbers to reduce ammonia (NH3) emissions from buildings on pig farms is one of the most promising techniques in the GÖteborg protocol and other European regulations including the Industrial Emission Directive. In France, some air scrubbers are currently used on pig farms, mainly to reduce odours from livestock buildings. However, recent research revealed the production of N2O resulting from the treatment of air from pig buildings. In this context, a two-month study was conducted on a pig farm with 750 places for fattening pigs to check the abatement of NH3 emissions and to assess the possible production of N2O during treatment of exhausted air from buildings housing fattening pigs by a air scrubber. Concentrations of NH3 and N2O in the inlet and outlet air of the scrubber were continuously monitored using an Innova 1412 infrared analyzer. With the scrubber operating parameters (airflow, design, size), our results confirmed the production of N2O in the order of 5% of NH3-N reduced. N2O was produced by biological nitrification and/or denitrification inside the air scrubber. Statistical analysis (Pearson’s test) showed that the production of N2O was strongly influenced by the rate of airflow and the outside temperature. The abatement of NH3 emissions from the building was only 33%, i.e. much lower than the 70% - 90% usually cited in the literature.

Characteristics of contaminants in water and sediment of a constructed wetland treating piggery wastewater effluent

Constructed wetland （CW） is the preferred means of controlling water quality because of its natural treatment mechanisms and function as a secondary or tertiary treatment unit. CW is increasingly applied in Korea for secondary effluent of livestock wastewater treatment. This study was conducted to recognize the characteristics of contaminants in the accumulated sediment at the bottom soil layer and to reduce the phosphorus release from sediments of the free water surface CW for the treatment of secondary piggery wastewater effluent from a livestock wastewater treatment facility. The results revealed that the dominant phosphorus existence types at near the inlet of the CW were non-apatite phosphorus （59%） and residual phosphorus （32%） suggesting that most of the particles of the influent are made up of inorganic materials and dead cells. Sediment accumulation is important when determining the long-term maintenance requirements over the lifetime of CW. Continuous monitoring will be performed for a further assessment of the CW system and design.

Effect of anaerobic digestion on the high rate of nitritation,treating piggery wastewater

The amount of piggery wastewater as domestic livestock is increasing.The volume of piggery wastewater produced is less than the volume of other wastewaters,but piggery wastewater has a heavy impact on wastewater streams due to an extremely high concentration of nitrogen and COD.In this study,laboratory reactors were operated using piggery wastewater and the effluent of anaerobic digester from piggery wastewater plants.The purpose of this study was to induce the nitritation process,which is an economically advantageous nitrogen removal method that converts ammonium nitrogen into nitrite.The results showed that the effluent of anaerobic digester from piggery wastewater was more efficient than raw piggery wastewater in terms of inducing nitritation.It can be deduced that nitritation is largely affected by an organic fraction of piggery wastewater.It can also be concluded that a small amount of biodegradable organic matter in piggery wastewater is efficient in inducing nitritation.

Rapid aerobic granulation in an SBR treating piggery wastewater by seeding sludge from a municipal WWTP

Aerobic sludge granulation was rapidly obtained in the erlenmeyer bottle and sequencing batch reactor（SBR） using piggery wastewater.Aerobic granulation occurred on day 3 and granules with mean diameter of 0.2 mm and SVI_（30） of 20.3 mL/g formed in SBR on day 18.High concentrations of Ca and Fe in the raw piggery wastewater and operating mode accelerated aerobic granulation,even though the seed sludge was from a municipal wastewater treatment plant（WWTP）.Alpha diversity analysis revealed Operational Taxonomic Units,Shannon,ACE and Chao 1 indexes in aerobic granules were 2013,5.51,4665.5 and 3734.5,which were obviously lower compared to seed sludge.The percentages of major microbial communities,such as Protect）acteria,Bacteroidetes and Firmicutes were obviously higher in aerobic granules than seed sludge.Chlorqflexi,Planctomycetes,Actinobactena,TM7 and Aridobacteria showed much higher abundances in the inoculum.The main reasons might be the characteristics of raw piggery wastewater and granule structure.

Numerical Modelling of Air Temperature and Velocity in a Forced Ventilation Piggery

Pigs are subjected to intensive environment control and management for higher productivity due to their sensitivity to climatic variation, which affects their growth. The aim of the current work is to numerically model the air speed and temperature in a forced ventilation piggery to achieve optimum environmental control. This work can also help to identify problems in the design of piggeries and offer suggestions for improvements. A steady two-dimensional numerical model including the effect of buoyancy, turbulence and heat generated by the pigs was solved using the computational fluid dynamics software Fluent, using the integral volume method. Air speed and temperature inside the piggery and at the pigs level were predicted for three different locations of ventilation opening, inlet velocities in the range (0.3 - 7 m/s), insulation or no insulation in the external walls, and for 5 ℃ and 32℃ ambient temperatures.

Comparative experiment on treating digested piggery wastewater with a biofilm MBR and conventional MBR： simultaneous removal of nitrogen and antibiotics

A biofilm membrane bioreactor （BF-MBR） and a conventional membrane bioreactor （MBR） were parallelly operated for treating digested piggery wastewater. The removal performance of COD, TN, NH4＋-N, TP as well as antibiotics were simultaneously studied when the hydraulic retention time （HRT） was gradually shortened from 9 d to 1 d and when the ratio ofinfluent COD to TN was changed. The results showed that the effluent quality in both reactors was poor and unstable at an influent COD/ TN ratio of 1.0±0.2. The effluent quality was signifcantly improved as the influent COD/TN ratio was increased to 2.3±0.5. The averaged removal rates of COD, NH4＋-N, TN and TP were 92.1%, 97.1%, 35.6% and 54.2%, respectively, in the BF-MBR, significantly higher than the corresponding values of 91.7%, 90.9%, 17.4% and 31.9% in the MBR. Analysis of 11 typical veterinary antibiotics （from the tetracycline, sulfonamide, quinolone, and macrolide families） revealed that the BF-MBR removed more antibiotics than the MBR. Although the antibiotics removal decreased with a shortened HRT, high antibiotics removals of 86.8%, 80.2% and 45.3% were observed in the BF-MBR at HRT of 5~4 d, 3-2 d and 1 d, respectively, while the corresponding values were only 83.8%, 57.0% and 25.5% in the MBR. Moreover, the BF-MBR showed a 15% higher retention rate of antibiotics and consumed 40% less alkalinity than the MBR. Results above suggest that the BF-MBR was more suitable for digested piggery wastewater treatment.

Raceway pond cultivation of a new Arthrospira sp.ZJWST-S1 in digested piggery wastewater treated by MBR and ozonation

A new Arthrospira strain named Arthrospira sp.ZJWST-S1 was isolated from a local digested piggery wastewater(DPW)storage pool in Jiaxing City,Zhejiang Province,China.It possessed good stain resistance against contaminants in DPW,which was pretreated with a membrane bioreactor(MBR).The strain was identified as Arthrospira platensis(A.platensis)based on its morphological characteristics and the 16S rDNA sequencing analysis.The effect of chrominance on growth of A.platensis ZJWST-S1 was investigated in a field raceway pond filled with MBR effluent or MBR effluent decolorized with ozonation.After ozonation,the chrominance of MBR effluent was decreased from 700 mg Pt/L to 150 mg Pt/L.Two runs of cultivation showed that A.platensis ZJWST-S1 grew faster in the ozone decolorized MBR effluent,the averaged biomass concentration being 0.907 g/L after 10 days of cultivation,close to that in a Zarrouk medium(0.969 g/L).By comparison,the biomass grew much slower in the non-decolorized MBR effluent(0.624 g/L).The pollutant removal was also benefited from the accelerative growth of A.platensis ZJWST-S1 in the decolorized MBR effluent.Almost all ammonium,61.2%of nitrate and 68.1%of phosphate were removed by the A.platensis ZJWST-S1 in the decolorized MBR effluent,much higher than the corresponding values of almost all ammonium,25.4%of nitrate and 36.5%of phosphate in the MBR effluent.Furthermore,the Arthrospira biomass harvested from the ozone decolorized MBR effluent after 10 d cultivation was with crude protein content of 59.1%±3.5%in dry algae powder.The content of Pb,As,Cd and Hg in biomass was also low enough to meet the Chinese Arthrospira Standard for Animal Feed(GB/T 17243-1998).This study showed that the new strain A.platensis ZJWST-S1 possessed potential to be used for producing animal feed and simultaneous removal of nitrogen and phosphorus in DPW.

Comparative study on microbial community in intermittently aerated sequencing batch reactors （SBR） and a traditional SBR treating digested piggery wastewater

A traditional sequencing batch reactor （SBR） and two intermittently aerated sequencing batch reactors （IASBRs） were parallelly operated for treating digested piggery wastewater. Their microbial communities were analyzed, and the nitrogen removal performance was compared during the long term run. IASBRs demonstrated higher removal rates of total nitrogen （TN） and ammonium nitrogen （NH4＋ -N） than the SBR, and also demonstrated higher resistance against TN shock load. It was found that the more switch times between aerobic/anoxic in an IASBR, the higher the removal rates of TN and NH4＋ N. All the reactors were predominated by Thauera, Nitrosomonas and Nitrobacter, which were considered to be species of denitrifiers, ammonium oxidizing bacteria （AOB） and nitrite oxidizing bacteria （NOB）, respectively. However, the abundance and diversity was of great difference. Compared with SBR, IASBRs achieved higher abundance of denitrification related bacteria. IASBR 1# with four aerobic/anoxic switch times was detected with 25.63% of Thauera, higher than that in IASBR 2# with two aerobic/anoxic switch times （l 1.57% of Thauera）, and much higher than that in the SBR （only 6.19% of Thauera）. IASBR 2# had the highest percentage of AOB, while 1ASBR 1# had the lowest percentage. The denitrifiers abundance was significantly positive correlated with the TN removal rate. However, the NH4＋ N removal rate showed no significant correlation with the AOB abundance, but might relate to the AOB activity which was influenced by the average free ammonium （FA） concentration. Nitrobacter was the only NOB genus detectable in all reactors, and were less than 0.03%.

Advantages of intermittently aerated SBR over conventional SBR on nitrogen removal for the treatment of digested piggery wastewater

An intermittently aerated sequencing batch reactor （IASBR） and a traditional sequencing batch reactor （SBR） were parallelly constructed to treat digested piggery wastewater, which was in high NH4＋ -N concentration but in a low COD/TN ratio. Their pollutant removal perfonnance was compared under COD/TN ratios of 1.6-3.4 d and hydraulic retention times of 5 3 d. The results showed that the IASBR removed TN, NH4＋-N and TOC more efficiently than the SBR. The average removal rates of TN, NH4＋-N and TOC were 83.1%, 96.5%, and 89.0%, respectively, in the IASBR, significantly higher than the corresponding values of 74.8%, 82.0%, and 86.2%. in the SBR. Mass balance of organic carbon revealed that the higher TN removal in the IASBR might be attributed to its efficient utilization of the organic carbon for denitrification, since that 48.7%- 52.2% of COD was used for denitrification in the IASBR, higher than the corresponding proportion of 43.1%-47.4% in the SBR. A prc-anoxic process in the IASBR would enhance the ammonium oxidation while restrict the nitrite oxidation. Anoxic duration of 40-80 min should be beneficial for achieving stable nitritation.

Viability of combining microalgae and macroalgae cultures for treating anaerobically digested piggery effluent

Algal phytoremediation represents a practical green solution for treating anaerobically digested piggery effluent(ADPE). The potential and viability of combining microalgae and macroalgae cultivation for the efficient treatment of ADPE were evaluated in this study.Bioprospecting the ability of different locally isolated macroalgae species illustrated the potential of Cladophora sp. to successfully grow and treat ADPE with up to 150 mg/L NH_4^+ with a biomass productivity of(0.13 ± 0.02) g/(L·day) and ammonium removal rate of(10.23 ± 0.18) mg/(L·day) NH_4^+. When grown by itself, the microalgae consortium used in this study consisting of Chlorella sp. and Scenedesmus sp. was found to grow and treat undiluted ADPE(up to 525 mg/L NH_4^+) with an average ammonium removal rate of 25 mg/(L·day) NH_4^+ and biomass productivity of(0.012 ± 0.0001) g/(L·day). Nevertheless, when combined together, despite the different cultivation systems(attached and non-attached) evaluated,microalgae and macroalgae were unable to co-exist together and treat ADPE as their respective growth were inversely related to each other due to direct competition for nutrients and available resources as well as the negative physical interaction between both algal groups.