饲料溶失对养殖水质的影响及其处置技术

Effects of Feed Dissolution on Water Quality and Its Treatment Technique in Aquaculture

为研究饲料溶失对养殖水质的影响及其解决途径,开展了2个阶段的试验:第1阶段,将1.0g粗蛋白含量≥28%的3种市售常用配合饲料加到2.0L蒸馏水和过滤的养殖池水中96h,探究长时间浸泡释放营养盐及有毒物质的过程;第2阶段,将索罗金小球藻Chlorella sorokiniana接种到1.2μm滤膜过滤的第1阶段处理液中培养8d,测定不同时间水体的硝酸盐、磷酸盐、铵态氮、亚硝酸盐含量及小球藻生长,考察小球藻去除氮磷及有毒物质的能力。试验在光照培养箱中进行,温度为(25±0.5)℃,每个容器均处于密封状态。结果显示:3种饲料在蒸馏水浸泡96h后硝酸盐含量达(0.785±0.171)mg/L,磷酸盐达(1.012±0.169)mg/L,铵态氮达(1.200±0.457)mg/L,亚硝酸盐为(0.030±0.009)mg/L;在养殖水中96h后,硝酸盐含量从(0.066±0.012)mg/L增至(1.465±0.108)mg/L,磷酸盐从(0.007±0.001)mg/L增至(1.747±0.224)mg/L,铵态氮从(0.016±0.002)mg/L增至(0.761±0.266)mg/L,亚硝酸盐从(0.007±0.001)mg/L增至(0.037±0.003)mg/L,增量分别为1.400mg/L、1.740mg/L、0.761mg/L和0.030mg/L;养殖水的营养释放较蒸馏水快。接种小球藻培养8d后,两个处理组中硝酸盐的去除率分别为77%和83%,磷酸盐为62%和56%,铵态氮为92%和89%;蒸馏水处理组小球藻OD680从接种时的(0.101±0.004)增加至(0.548±0.099),增加了0.446,生物量平均增加了2.126g/L;养殖原水组OD680从(0.104±0.002)增加至(0.758±0.131),增加了0.654,生物量平均增加了3.115g/L。研究表明:饲料浸泡的营养释放使水体氮、磷等含量迅速升高;小球藻对此引起的水体营养加富具有较好的吸收净化效果。

Two stages of experiments were carried out: in the first stage, 1.0 g of three types of each commercial common formulated feeds containing crude protein content of ≥ 28% was added to 2.0 L distilled water and filtered pond culture water for 96 h to explore the process of releasing nutrients and toxic substances from the feeds exposed to long-term immersion;in the second stage, green alga Chlorella sorokiniana was inoculated into the water in the first stage filtered by 1.2 μm filter membrane, and the contents of nitrate,phosphate, ammonium nitrogen, nitrite and OD680 values of the green alga were measured at different time, to investigate the ability of the alga to remove nitrogen, phosphorus and toxic substances in order to study the effect of feed loss on water quality and its solution.The test was carried out in a light incubator with a temperature of(25 ± 0.5)℃, and each container was in a sealed state. The results showed that the contents of nutrients in the feed distilled water was(0.785 ± 0.171)mg/L in nitrate,(1.012 ± 0.169)mg/L in phosphate, and(1.200 ± 0.457)mg/L in ammonium nitrogen, and(0.030 ± 0.009)mg/L in nitrite. In the pond culture water, however,the nitrate content was increased from(0.066 ± 0.012)mg/L to(1.465 ± 0.108)mg/L, the phosphate from(0.007 ± 0.001)mg/L to(1.747 ± 0.224)mg/L, ammonium nitrogen from(0.016 ± 0.002)mg/L to(0.761 ± 0.266)mg/L, and nitrite from(0.007 ±0.001)mg/L to(0.037 ± 0.003)mg/L, with increments of 1.400 mg/L in nitrate, 1.740 mg/L in phosphate, 0.761 mg/L in ammonium nitrogen, and 0.030 mg/L in nitrite;the rapid nutritional release in the pond culture water than that in distilled water. The removal rates in the two treatment groups inoculated with green alg for 8 d were found to be 77% and 83% in nitrate, 62% and 56% in phosphate,and 92% and 89% in ammonium nitrogen. The OD680 value in the distilled water treatment group was increased from(0.101 ± 0.004)at the time of inoculation to(0.548 ± 0.099), an increase of 0.446, and Biomass increased by an average of 2.126 g/L;the OD680 value in the aquaculture water group was increased from(0.104 ± 0.002)to(0.758 ± 0.131), an increase of 0.654, and Biomass increased by an average of 3.115 g/L. The findings indicated that the nutritional releasing of feed immersion resulted in increase in levels of nitrogen, phosphorus rapidly, seriously polluted the water quality, and that green alga inoculation was a good solution to purify the polluted water and a good method for the aquaculture wastewater treatment.