Phosphorus recovery: a need for an integrated approach

Increasing cost of phosphate fertilizer, a scarcity of high quality phosphate rock (PR)and increasing surface water pollution are driving aneed to accelerate the recovery and re-use ofphosphorus (P) from various waste sectors. Options to recover P occur all along the open P cycle from mining to households to oceans. However, P recovery as a regional and global strategy towards P sustainability and future food, bio energy and water security is in its infancy because of a number of technological, socio-economic and institutional constraints. There is no single solution and resolving these constraints requires concerted collaboration betweenrelevant stakeholders and an integrated approach combiningsuccessful business models withsocio-economic and institutional change. We suggest that an operational framework is developed for fast tracking cost-effective recovery options

Phosphorus recovery from waste - methods review

According to sustainable development principles, searching for alternative phosphorus sources, especially possible ways of its recycling from waste, should be treated as a preferential problem of the phosphorus industry. The ways admitted as most important are: - phosphorus recovery from municipal and industrial sewage and from sewage sludge, - utilization of phosphorus from manure, - management of waste from meat industry. The forecasts elaborated at the end of the last century, indicate that over 50% of the world phosphorus resources in use today will be depleted during the next 60 - 70 years. That fact contributes to increase of market prices of phosphorus products. This work presents possible directions for the recovery and management of sewage sludge, meat meal and manure as a phosphorus source for chemical industry

Phosphorus recovery from waste - methods review

According to sustainable development principles, searching for alternative phosphorus sources, especially possible ways of its recycling from waste, should be treated as a preferential problem of the phosphorus industry. The ways admitted as most important are: - phosphorus recovery from municipal and industrial sewage and from sewage sludge, - utilization of phosphorus from manure, - management of waste from meat industry. The forecasts elaborated at the end of the last century, indicate that over 50% of the world phosphorus resources in use today will be depleted during the next 60 - 70 years. That fact contributes to increase of market prices of phosphorus products. This work presents possible directions for the recovery and management of sewage sludge, meat meal and manure as a phosphorus source for chemical industry

From sewage sludge ash to calcium phosphate fertilizers

Our work presents the results of the research on the utilization of ashes after sewage sludge combustion comprising phosphorus recovery in the form of useful products. The investigations were divided into three parts: selecting the combustion parameters of sewage sludge, examining ash leaching with mineral acids (nitric and phosphoric) to high phosphorus selectivity assuring a low content of iron and heavy metals in the extracted solutions and precipitation of CaHPO4 .2H2O. Suitable temperature of a sewage sludge combustion enables selective extraction of phosphorus compounds from ash because of hematite phase forming, insoluble in mineral acids. The extracts from phosphoric acid leaching, where the extraction of phosphorus compounds was 96.1%, have very good properties for its further use as the initial solution for CaHPO4 .2H2O with 6% lime milk. The obtained product is characterized by high purity and phosphorus availability compatible even with the feed phosphate standard

Potencial management of waste phosphogypsum with particular focus on recovery of rare earth metals

Phosphogypsum is a noxious industrial waste contributing to global environmental and economic problems. This publication focuses above all on phosphogypsum resulting from the processing of apatite as a phosphorus bearing compound, since it contains considerable amounts of lanthanides due to its magma origin. The possibilities of its waste-free processing are large, however they require the application of suitable technologies, frequently expensive ones, and allowing for the individual characteristics of the given waste. The research works conducted so far confirm the possibility of applying phosphogypsum for the recovery of lanthanides, and the process enhances the removal of remaining impurities, thanks to which the purified calcium sulphate (gypsum) may find application for the production of construction materials

The influence of thermal processing of sewage sludge on the usage properties of the formed ash

The influence of sewage sludge incineration temperature on the formed ash constitution was examined. The comparative extraction tests of two differently prepared ashes (laboratory and industrial) were carried out in order to verify if the parameters of sewage sludge incineration influence the extraction selectivity of phosphorus compounds. The laboratory ash (A(lab)) were prepared from sewage sludge incinerated at 950°C on a laboratory scale while the industrial ash (A(ind)) comes from thermal utilization system of the sewage sludge at the Gdynia Sewage Treatment Plant, which uses fluid-bed furnace incineration at 850 - 900°C. It was found that the temperature and the conditions of the sewage sludge incineration process have an effect on the usage properties of the formed ash. Despite the twofold lower Fe content in the industrial ash than that of the laboratory one, its content in extracts after phosphoric acid leaching is 4.7 times higher. The lower values of PO4^3- leaching degree from the industrial ash than the laboratory ash were observed, as well as a decrease of extraction productivity

Increasing the bulk density of STPP - influence of the process parameters

The new requirements that were placed on STPP, like high bulk density, the proper relation of Form I and Form II and suitable physicochemical properties, resulted in the development of the present production methods. The paper presents the research results on increasing the bulk density of STPP by a chemical method. In the introduced method the solid sodium phosphate from spray drying and sodium orthophosphate solution, after acid neutralization, were rubbed together. Such an operation changes the physicochemical properties of the dried sodium phosphate before calcining, which results in increasing the bulk density of STPP to a level of 0.80 kg/dm3. The dependence of STPP bulk density on process parameters such as: sodium orthophosphate solution to solid sodium phosphate mass ratio, temperature of dosed sodium orthophosphate solution, as well as the calcining temperature of mixtures were analysed

A chemical method of the production of "heavy" sodium tripolyphosphate with the high content of Form I or Form II

Sodium tripolyphosphate STPP is used in laundry detergent as a detergent "builder". The paper presents the chemical method of obtaining "heavy", i.e. with higher bulk density granulated sodium tripolyphosphate. The bulk density of sodium tripolyphosphate was increased by preparing a mixture of the dried sodium phosphates, the recycled subgrain of STPP and water in specific proportions and calcining this mixture for 1 hour at 400°C and 550°C (to obtain a proper STPP form) in the chamber kiln. This method allows producing the granular sodium tripolyphosphate with high bulk density (1.04-1.07 kg/dm3) and a high content of Form I or Form II, respectively