Breeding environment
1. Raise the water level in the pond. In view of the low water level in the pond and the poor water source in the outer river, the pond water is gradually added several times every once in a while, so that the pond water level is gradually raised to more than 1.2 meters, and water is added every morning 10 to 2 pm on sunny days.
2. Increase dissolved oxygen in water. If there is oxygen-increasing equipment, the oxygen-increasing machine can be turned on for more than 2 hours at noon on sunny days, and it should be turned on in time in case of rainy days or sudden weather changes. If there is no aerator, you can use a submersible pump to pump the circulating water in the pool (before 3 pm, never at night) to strengthen the convection and exchange of water.
3. Biological control of water quality. All kinds of cultured varieties have entered the golden age of growth, but while eating vigorously, their excreta has also increased obviously, which has accelerated the deterioration of water quality. Therefore, it is suggested to use biological agents made of various microbial strains to control water quality. Please use it correctly according to the instructions for specific usage, dosage and precautions.
4. The crabs in the outer river network should be sheltered by aquatic plants to reduce direct glare and water temperature. In the case of lack of oxygen, the propeller of the gondola can be used to push water to increase oxygen and increase water flow.
Refer to Baidu Encyclopedia entry Aquaculture/Qita/201609/3513.html.
Two. Treatment of aquaculture wastewater
3. 1 physical processing technology
Conventional physical treatment technology mainly includes filtration, neutralization, adsorption, precipitation, aeration and other treatment methods, which is an important part of wastewater treatment technology. Mechanical filtration and foam separation technology are effective methods for the discharge and recycling of industrial aquaculture wastewater.
(1) filtration technology
Because most of the residual bait and excrement of aquaculture wastewater exist in the form of suspended large particles, physical filtration technology is the fastest and most economical method to remove it. Commonly used filtration equipment includes mechanical filter, pressure filter and sand filter. [1] In practical treatment engineering, mechanical filtration (microfiltration) is a way with more applications and better filtration effect. Zeolite filter has both filtering and adsorption functions, which can not only remove suspended solids, but also effectively remove dissolved pollutants such as heavy metals and ammonia nitrogen through adsorption [2].
(2) Foam separation technology
Since 1970s, foam separation technology has been widely used in industrial wastewater treatment. Its principle is to introduce air into the treated water body, so that the surface active substances in the water are adsorbed by tiny bubbles and float to the water surface with the bubbles to form foam, and then the foam on the water surface is separated, thus achieving the purpose of removing dissolved and suspended pollutants in wastewater. Because foam separation technology can not only remove protein and other organic substances before they are mineralized into ammoniated toxic substances, but also provide necessary dissolved oxygen for aquaculture water, which has a good effect on maintaining the ecological environment of aquaculture water.
3.2 Chemical treatment technology
There are suspended substances such as aquaculture biological excreta, ammonia nitrogen, biodegradable organic matter and refractory organic matter in seawater industrial aquaculture wastewater. Therefore, using the oxidation of ozone, hydrogen peroxide, chlorine dioxide, bleaching solution and other chemical oxidants, oxidative decomposition of refractory dissolved organic matter is the main means of advanced treatment of aquaculture wastewater. Ozone oxidation technology has been widely used in circulating water treatment of mariculture system in western Europe, the United States and Japan [5]. In addition, ozone can not only rapidly reduce COD in seawater, but also greatly reduce the concentration of ammonia nitrogen and nitrite in water [3]. But the amount of ozone consumed is very large. Therefore, using O 3/UV process can not only improve the treatment efficiency, but also reduce the ozone consumption. Using O 3/UV technology to purify lake water can achieve the purpose of purifying water quality and increasing oxygen content in water body [6]
3.3 Bioremediation Technology
Bioremediation includes biodegradation, biological absorption, accumulation and transformation. Bioremediation can eliminate pollutants or change the existing forms of pollutants to reduce their toxicity and restore or rebuild degraded or destroyed ecosystems. The biggest feature of bioremediation is that it will not introduce a lot of foreign substances into the system, but it works through the energy acting on the organism itself; On the other hand, under suitable conditions, living organisms reproduce themselves without or with little artificial energy, which is a spontaneous process. Bioremediation includes microorganism, plant and aquatic animals.
(1) Microbial action
At present, the most widely used microbial purification technologies at home and abroad are microbial inoculation technology and biofilm technology. Inoculation technology is to directly inoculate exogenous pollution-degrading bacteria into polluted water, and then use the added microorganisms to activate the originally existing, inhibited but ineffective microorganisms in water, and effectively control the growth and activities of harmful microorganisms in the environment and resources through their rapid proliferation, thus eliminating the organic pollution and eutrophication of water. At present, the commonly used technologies at home and abroad include centralized biological system (CBS), efficient complex microbial flora (em), immobilized bacteria and so on. CBS technology is a high-tech bioremediation technology developed by scientists from CBS Company in the United States. It is a virtuous circle microbial system composed of dozens of microorganisms with different functions. From March to April, 2000, the Taohuaxi River in Chongqing was purified by CBS technology. The results show that the removal rates of BOD, COD, nitrogen and phosphorus are 83. 1%~ 86.6%, 74.3% ~ 80.9%, 53% ~ 68.2% and 74. 3% ~ 80.9%, and the purification effect is very obvious. [7] Immobilized microorganism technology is a technology that fixes biochemical treatment strains in a microenvironment suitable for their reproduction and growth through certain embedding methods, thus effectively degrading part of aquaculture wastewater.
The use of some specific pollutants [8]. At present, the high-density biochemical mixed bacteria obtained by enrichment, culture and screening are usually embedded in gel materials such as sodium alginate and PVA [1]. In this way, relatively poor bacteria in natural seawater environment form dominant bacteria in the embedding system, and the bacteria after biochemical treatment in the embedding system are not easy to be lost at will, thus achieving the purpose of effectively treating aquaculture wastewater. Because of the high density, strong activity and fast reaction speed of immobilized microorganisms, compared with the conventional microbial biofilm biochemical treatment technology, it has significant removal effect on ammonia nitrogen and some refractory organic substances [9], so this technology is expected to become an important biochemical treatment technology for seawater industrial aquaculture wastewater treatment. Biofilm technology is that wastewater continuously flows through solid fillers (gravel, plastic fillers, etc.). ), and biofilm will be formed on the filler, which will breed a large number of microorganisms and play a role in purifying wastewater. Biofilm process has a variety of treatment structures, including biological filter, biological turntable, biological contact oxidation and biological fluidized bed. You can also use * * *
Metabolism, using the interaction between microorganisms and plants or animals to obtain decontamination effect [10].
(2) Plant action
Macroalgae can absorb and fix nutrients such as C, N and P in water through photosynthesis to synthesize themselves, and at the same time increase dissolved oxygen in water. The analysis of chemical composition of macroalgae shows that macroalgae is rich in nitrogen pool and can absorb and store a large number of nutrients efficiently. The nutrient pools in macroalgae tissues generally include inorganic nitrogen pools, amino acid nitrogen pools, non-protein soluble organic nitrogen pools (such as chlorophyll and phycoerythrin) and protein nitrogen pools (such as enzymes) [1 1]. In the fish culture system in small water body, using algae to absorb inorganic nutrients in aquaculture wastewater can reduce about 50% NH 4-N in water body and increase the net algae yield 18%.
[12], in addition, macroalgae also have strong tolerance and cleaning effect on polluted environment. It has been reported that planting macroalgae in the sea area polluted by metals and organic matter can improve the DO of water body, reduce the contents of BOD, POC, copper, zinc, lead and cadmium, and promote the recovery of polluted areas [13]. Can effectively enrich algae.
Collect and degrade pesticides, alkanes, azo dyes, starch, phenols, phthalates, organometallic dyes and other organic substances (Yan Guoan, 1995).
(3) the role of aquatic animals
In recent years, many scholars and researchers at home and abroad have devoted themselves to purifying sewage by using the absorption and utilization of organic and inorganic substances in water by aquatic animals, and achieved remarkable results by directly absorbing nutrients, organic debris, bacteria and phytoplankton by aquatic animals. Aquatic animals that can purify sewage mainly include filter-feeding fish and bivalves.
Small zooplankton such as shellfish and Daphnia.
{1}. Purification of fish?
Shadowfish, which lives in the ocean and uses benthic algae and multicellular plant fragments as bait, is the main fish in shrimp ponds in Taiwan Province Province, China. In addition, barracuda, mullet and Mozambican tilapia can also use algae and organic debris, which can be mixed with prawns to purify water. According to the analysis of feeding habits of mullet, putrid organic matter accounts for 38% ~ 50%, sand accounts for 28%~ 30%, cyanobacteria 12%~ 16%, diatom 15% ~ 18%, and invertebrate 0. 2% ~ 2%.
{2} Purification of bivalve shellfish? Most bivalves filter plankton, organic debris and other bait in water, and through their filtering activities, water quality can be purified. In shrimp ponds, SINONOVACULA SINONOVACULA, Oyster, Meretrix meretrix and scallop can be mixed, which reduces the eutrophication of pond water and has high economic value.
According to Zhang Deyu (199 1), the mixed culture of scallops in shrimp ponds can purify the water quality. Before stocking scallops, the chemical oxygen consumption was 6. 5mg/ L, reduced to 2 after stocking scallops. August/kloc-70 mg/l on 0/8 and 2. In August 2005, 65438+24 mg/L.
{3}. Purification function of small zooplankton such as Daphnia?
The food of small zooplankton such as Daphnia is mainly bacteria, unicellular algae and organic debris, and its filtration activity also has the function of purifying water quality.
{4}. Problems and development prospects of biological purification
Traditional microbial treatment technologies mostly select and breed naturally growing microbial populations, and the degradation level of pollutants is low. Therefore, it is necessary to genetically modify and directionally select engineering strains with high degradation ability to environment and resources, so as to greatly improve the degradation ability of microorganisms to meet the requirements of wastewater treatment [14]. The artificially constructed genetically engineered bacteria for degrading pollutants generally have fast growth speed, good flocculation performance and high specific degradation ability for refractory pollutants and toxic and harmful pollutants. Many strains with heavy metal resistance genes have been found, such as mercury resistance, cadmium resistance and lead resistance. The purification function of organisms depends on the catalysis of biological enzymes. In order to improve students' health
Enzyme activity and immobilization technology are very active research directions at present. The cell is multienzyme system, and the immobilized cell has good stability, high catalytic efficiency and low cost, so the immobilized cell technology has attracted extensive attention at home and abroad, and achieved many results.
Refer to the treatment method of aquaculture wastewater in No.2 Aquatic Products Institute of Hebei Province in 2007 (total number 158) (Zheng Jiarui)