WTP (Wastewater Treatment Plant) seminar for vaname shrimp culture was held on March 29, 2022 in Probolinggo. The speakers came from IPB University, there are Dr. Kukuh Nirmala, an expert in physics chemistry in aquatic, and Dr Yuni Puji Astuti, an expert in aquatic microbiology.
Dr. Kukuh Nirmala as the first speaker started by explain detailed about dynamics of bacteria and plankton in aquaculture ponds. Diversity of plankton has important role in aquaculture. However, water quality in shrimp culture has degradation quality along day of culture (DOC) and it will cause break disease in shrimp culture. For example at Myo disease, this disease is triggered by high nitrite in water pond and shrimp become stressfull causes methaemocyanin. Hemocyte cant to bind oxygen even though in high DO condition.
AHPND disease happen if plankton in the aquaculture crashes. Crash means that blue green algae (BGA) dies and BGA will produce toxic that attack hepatopancreas. Highly BGA in shrimp culture is indicated by many jellyfish come around coast. Other dangerous of algae aside BGA are dinoflagellates and prymnesium. Dr. Yuni Puji Astuti added that plankton population is also affected by the season. In the rainy season, cyanobacteria also increase.
In 1 hectare of shrimp ponds will produce 15,000 tons of waste water, 1.4 tons of organic matter from untake feed and feces, and 2.6 tons of ammonia. Aquaculture waste must be treated before released into the sea. Based on related research in several areas, based on tidal current patterns indicator, sea water only rotates around the coast. If waste shrimp culture hasnt good waste water treatment, it can return to the shrimp culture and cause several diseases.
Another negative effect is changing the C:N:P ratio of the waters. Changes in the C:N:P ratio in shrimp culture also will change diversity of plankton and it cause changes in bacterial stratification. Specific bacterial change in an aquatic environment will cause changes in the plankton that grows in. In addition about changes C:N:P ratio, other negative impacts are sedimentation/silting on the coast, DO decomposition (dead zone/anaerobic), and harmfull plankton blooms.
Dr. Kukuh Nirmala proposes that the waste shrimp culture can be used directly as organic fertilizer with dilution treatment. Research on horticulture explains that sweet taste in fruit can be influenced by soil minerals. Other studies have shown that giving water with certain salinity for livestock will have good impact on growth, livestock are relatively resistant in disease, and meat tastes better. Another alternative to use aquaculture waste is using bio-conversion products with economic value, for example sea cucumbers and oysters.
To support sustainable shrimp culture, application of WTP (Wastewater Treatment Plant) firstly must understand about the principles of WTP. The principles are sedimentation, adsorption, and filtration. Sedimentation being first treatment and it needed to treat particles from organic matter (untake feed and feces). Chemical treatment that we use are oxygenation, neutralization, coagulation-flocculation by liming and alum treatment and it change to floc and reduce TDS but pH and oxygen levels will increase. Meanwhile, biological treatment using by bioremediation, phytoremediation, and bio-phytoremediation methods.
There is biogeochemical cycle in WTP process which has much organic and inorganic waste come in and energy pathways for dominant bacteria (heterotrophs and chemoheterotrophs). Area of WTP depends on density shrimp culture that we used. Based on FAO standards, for intensive method shoud to 10-20% of waste water goes to the WTP pond (750m2), 5-10% wastewater (375m2) for semi-intensive, and 185m2 or <5% wastewater goes to the WTP (185m2) for the traditional method.
There are two variations of WTP’s design was recommended by Dr Yuni Puji Astuti. First design is WTP with 4 stages, there are sedimentation pond (sludge reactor form), a filtration pond, an aerobic and anaerobic remediation pond, and a disinfection pond. Notes about aerobic pond, bio-bacterial types and type of enzymes that are given must be known well, so remediation process runs optimally. Second design of WTP is round mini (an inverted funnel with sludge drain). Second design more compatible for cluster scale shrimp culture.
A WTP design that has been used at BRPBAP Takalar is WTP design has 3 stages: sedimentation pond, an aerobic pond, and maturation pond with the same principles as described above. In Indonesia, standard quality for aquaculture wastewater have not been established and being important issue. To support sustainable shrimp farming in Indonesia hopefully standardization in quality wastewater aquaculture will be released soon.