Treatment of piggery wastewater through struvite precipitation and nitrogen removal bacteria and poly-phosphate bacteria (in-pots experiment)
Abstract
Piggery wastewater is a type of wastewater which contains large amounts of nitrogen and phosphorus, therefore it needed to be treated before releasing to directly to the environment. The combination between struvite precipitation and nitrogen removal and poly-P bacteria into wastewater for piggery wastewater treatment has been found to be a cost-effective practice, a viable technology in terms of environmental protection and sustainability, especially in the developing-countries. For optimum struvite crystallization from piggery wastewater, the Mg:PO4 molar ratio as (1.2:1) was used, the pH of reaction was adjusted to 9 and the sample was stirred continuously during 40 minutes. The supernatant sample was then added 1% nitrogen removal bacteria (Pseudomonas stutzeri D3b strain) and 1% poly-P bacteria (Kurthia sp. TGT1013L strain), 5 g glucose/L and aeration 12/24h during 3 days, ammonium concentration reduced significantly from 1271 mg/L to 1.2 mg/L and orthophosphate concentration decreased noticeably from 24.91 mg/L to 16.1 mg/L.
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Introduction
Wastewaters contain a high amount of organic matter, nitrogen and phosphorus, a considerable amount of Mg, different macro and micro elements, and heavy metals due to which it is considered as one of the major polluting agents discharged into the environment. The livestock waste stream is therefore, very rich in phosphorus. A significant amount of nitrogen comes out through excreta as a residue of protein supplement as well as dead animals. Improper management of livestock waste creates a nuisance and obnoxious environment which also greatly affect on public health. Some forms of nitrogen (ammonia, nitrite, and nitrate) and phosphorus (orthophosphate and monophosphate) produce toxicity in the water and affect on aquatic life. It is obligatory to remove nitrogen and phosphorus from wastewaters before discharging it into the water stream to create an eco-friendly, pollution-free environment. So, many countries are paying attention to water pollution resulted from wastewaters, and have tightened legislation and discharging standards.
Great efforts have been done by researchers for the removal of nitrogen from wastewater through biological nitrification and denitrification, ammonia-stripping, electrochemical conversion, ion exchange, microwave irradiation and struvite precipitation.
Wastewater that contains high concentration of N, and P is an effective source of struvite recovery. In recent years, struvite has been recovered from different types of wastewaters, such as swine wastewater, calf manure wastewater, leather tanning wastewater, sewage sludge, dairy wastewater, wasted sludge, digester supernatant, industrial wastewater, municipal land fill leachate, lagoon wastewater, poultry manure wastewater, agro-industrial wastes, slaughterhouse wastewater, anaerobic digester effluents, synthetic wastewater, slurry type swine wastewater, animal manure, urine and fertilizer plant wastewater.
Conclusion
Production of struvite from wastewaters will reduce the hazard of eutrophication in the water bodies by removing N and P. Production of struvite from wastewater and its utilization as fertilizer would partially help to reduce global warming and thus, it would be an effective eco-friendly fertilizer. Treatment of piggery wastewater consisting of struvite eviction and removal of nitrogen and phosphate using nitrogen removal bacteria and poly-P bacteria were high effectiveness and low cost.
